using adams/car - md adams 2010

Welcome to Adams/Car

Adams/CarAbout Adams/Car

2

About Adams/CarAdams/Car, part of the MD Adams 2010® suite of software, is a specialized environment for modeling vehicles. It allows you to create virtual prototypes of vehicle subsystems and analyze the virtual prototypes much like you would analyze the physical prototypes.

Using Adams/Car, you can quickly create assemblies of suspensions and full vehicles, and then analyze them to understand their performance and behavior.

You create assemblies in Adams/Car by defining vehicle subsystems, such as front and rear suspensions, steering gears, anti-roll bars, and bodies. You base these subsystems on their corresponding standard Adams/Car templates. For example, Adams/Car includes templates for double-wishbone suspension, MacPherson strut suspension, rack-and-pinion steering, and so on.

If you have expert-user access, you can also base your subsystems on custom templates that you create using the Adams/Car Template Builder.

When you analyze an assembly, Adams/Car applies the analysis inputs that you specify. For example, for a suspension analysis you can specify inputs to:

• Move the wheels through bump-rebound travel and measure the toe, camber, wheel rate, roll rate, and side-view swing arm length.

• Apply lateral load and aligning torque at the tire contact path and measure the toe change and lateral deflection of the wheel.

• Rotate the steering wheel from lock to lock and measure the steer angles of the wheels and the amount of Ackerman, that is, the difference between the left and right wheel-steer angles.

Based on the analysis results, you can quickly alter the suspension geometry or the spring rates and analyze the suspension again to evaluate the effects of the alterations. For example, you can quickly change a rear suspension from a trailing-link to a multi-link topology to see which yields the best handling characteristics for your vehicle.

Once you complete the analysis of your model, you can share your work with others. You can also print plots of the suspension characteristics and vehicle dynamic responses. In addition, you can access other users' models without overwriting their data.

Benefits of Adams/CarAdams/Car enables you to work faster and smarter, letting you have more time to study and understand how design changes affect vehicle performance.

Using Adams/Car you can:

• Explore the performance of your design and refine your design before building and testing a physical prototype.

• Analyze design changes much faster and at a lower cost than physical prototype testing would require. For example, you can change springs with a few mouse clicks instead of waiting for a mechanic to install new ones in your physical prototype before re-evaluating your design.

3Welcome to Adams/CarAbout Adams/Car

• Vary the kinds of analyses faster and more easily than if you had to modify instrumentation, test fixtures, and test procedures.

• Work in a more secure environment without the fear of losing data from instrument failure or losing testing time because of poor weather conditions.

• Run analyses and what-if scenarios without the dangers associated with physical testing.

Adams/CarAbout Adams/Car

4

Learning the Basics

Adams/CarStarting Adams/Car

6

Starting Adams/CarIn the Windows environment, you start Adams/Car from the Start button. In the UNIX environment, you start Adams/Car from the Adams Toolbar. For more information, see Running and Configuring Adams.

This topic describes how you start the two Adams/Car Interface Modes, standard interface or template builder.

Adams/Car Standard Interface Adams/Car has two interface modes: Standard Interface and Template Builder. This topic explains how to start Adams/Car Standard Interface.

To start in the Windows environment:

1. From the Stat menu, point to Programs, point to MSC.Software, point to MD Adams 2010, point to ACar, and then select Adams - Car.

The Welcome Dialog Box appears on top of the Adams/Car main window.

2. Do one of the following:

• If the Welcome dialog box contains the options Standard Interface and Template Builder, select Standard Interface, and then select OK.

• If the Welcome dialog box does not contain any options, then Adams/Car is already configured to run in standard-interface mode. Select OK.

The Adams/Car Standard Interface appears.

To start in the UNIX environment:

1. At the command prompt, enter the command to start the Adams Toolbar, and then press Enter. The standard command that MSC.Software provides is mdadamsx, where x is the version number, for example mdadams2010.

The Adams Toolbar appears.

2. Select the Adams/Car tool .



• If the Welcome dialog box contains the options Standard Interface and Template Builder, select Standard Interface, and then select OK.

• If the Welcome dialog box does not contain any options, then Adams/Car is already configured to run in standard mode. Select OK.

The Adams/Car Standard Interface appears.

7Learning the BasicsStarting Adams/Car

Adams/Car Template Builder Adams/Car has two interface modes: Standard Interface and Template Builder. This topic explains how to start Adams/Car Template Builder.

Before you start Adams/Car Template Builder, make sure that your private configuration file, .acar.cfg, shows that you have expert-user access. Your private configuration file is located in your home directory.

To check user access:

1. In a text editor, such as jot or notepad, open .acar.cfg.

2. Verify that the following line appears as shown:

ENVIRONMENT MDI_ACAR_USERMODE EXPERTThis line sets the user mode for the Adams/Car session.

To start in the Windows environment:

1. From the Start menu, point to Programs, point to MSC.Software, point to MD Adams 2010, point to ACar, and then select Adams - Car.


2. Select Template Builder.

3. Select OK.

The Adams/Car Template Builder window appears.

To start in the UNIX environment:

1. At the command prompt, enter the command to start the Adams Toolbar, and then press Enter. The standard command that MSC.Software provides is mdadamsx, where x is the version number, for example mdadams2010.

The Adams Toolbar appears.

2. Select the Adams/Car tool .


3. Select Template Builder.

4. Select OK.

The Adams/Car Template Builder window appears.

Adams/CarInterfaces and Access

8

Interfaces and AccessYou can use Adams/Car through two different interfaces depending on your user access.

Interface Modes Adams/Car has two interface modes:

• Standard Interface - You use it when working with existing templates to create and analyze assemblies of suspensions and full vehicles. Users with standard and expert access can use the Standard Interface.

• Template Builder - If you have expert-user access, you use the Template Builder to create new templates for use in the Standard Interface.

When you create a new component in the Template Builder, your product automatically adds a prefix based on the entity type and the symmetry. Your product uses a naming convention to let you easily determine an entity’s type from the entity’s name. Learn about the naming convention and see a table that lists the prefixes of various entities. If you have expert-user access, you use the Template Builder to create new templates for use in the Standard Interface.

Using the Template Builder, you can assemble standard components, such as springs, parts, and bushings, to define the topology of your system, such as a suspension or a single valvetrain in an engine.

To switch between modes:

Do one of the following:

• From the Tools menu, select [Product Name] Standard Interface or select [Product Name] Template Builder.

• Press F9.

About User AccessYour access to the standard-interface or template-builder mode depends on your assigned user access:

• Standard user - Standard users do not have access to the Template Builder, only to the Standard Interface. Therefore, the standard user cannot make topological modifications to templates, but can operate on subsystems, varying design parametrics and analysis inputs.

• Expert user - Expert users have access to modeling capabilities available in theTemplate Builder. Therefore, expert users can open templates and modify their topological information, as well as create new templates.

If you are an expert user, when you launch your Adams product, it prompts you to select either Standard Interface or Template Builder.

9Learning the BasicsInterfaces and Access

Setting User AccessYou use the MDI_ACAR_USERMODE keyword in your private configuration file to set your user access, which determine you access to the Template Builder and other development tools. Your private configuration file is found at $HOME/.acar.cfg, where $HOME is the location of your home directory.

You can set USERMODE to:

• STANDARD - User can only access the Standard Interface.

• EXPERT - User can access the Template Builder and create and modify templates. User can access the Template Builder and other development tools that are located under the Tools menu. Expert users can use the MDI_ACAR_PLUS_AVIEW keyword in the private configuration file to access Adams/View. Learn about accessing Adams/View.

To change the value of this keyword, you must edit the private configuration file (.acar.cfg) using a text editor and modify the corresponding string. The following gives you expert access:

! Desired user mode (standard/expert)

ENVIRONMENT MDI_ACAR_USERMODE EXPERT

When you start a new session, your template-based product reflects the changes to the private configuration file.

Note: The private configuration file is not located in the installation directory. Never change the acar.cfg file located in the installation

Adams/CarNavigating Through a Modeling Database

10

Navigating Through a Modeling DatabaseThe Database Navigator helps you view, select, and modify objects in your Modeling database.

Learn more:

• About the Database Navigator

Viewing Objects

• Showing, Hiding, and Selecting Objects in the Database Navigator

• Managing the Select List

• Filtering Objects in the Database Navigator

• Sorting Objects in the Database Navigator

• Setting Highlighting in the Database Navigator

Changing Objects

• Setting Appearance of Objects Through the Database Navigator

• Renaming Objects Through the Database Navigator

• Adding Comments Through the Database Navigator

Viewing Information About Your Model

• Viewing Model Topology Through the Database Navigator

• Viewing the Associativity of Objects

• Viewing Object Information Through the Database Navigator

• Viewing Model Topology Map Through Information Window

About the Database NavigatorThe Database Navigator has several modes in which you can display object information. It can be set to just let you browse for objects or you can set it to rename objects, view information about the objects, such as view how the object relates to other objects, and view dependencies.

The Database Navigator only displays the types of objects that are appropriate for the command you are executing. For example, if you are renaming a model, it only displays models in your database. On the other hand, if you are searching for any modeling object in the database, it displays all types of modeling objects. You can also set a filter for the types of objects that the Database Navigator displays.

The Database Navigator shows objects in their database hierarchy. The following figure shows the Database Navigator with the top-level modeling objects in a small database that contains one model,

11Learning the BasicsNavigating Through a Modeling Database

model_1 . These objects do not have parents. Double-click the name of a model, in this case model_1, to find all the objects belonging to that model.

To display the Database Navigator, do any of the following:

• From the Tools menu, select Database Navigator.

• Execute an editing command, such as Modify, from the Edit menu when no object is currently selected.

• Request to view information about an object using the Info command on the Edit pop-up menu.

• Browse for the name of an object to enter in a dialog box using the Browse command.

Your template-based product displays the Database Navigator.

Showing, Hiding, and Selecting Objects in the Database NavigatorIn the Database Navigator Tree list,a plus (+) in front of an object indicates that the object has children below it but they are hidden. A minus (-) indicates that all objects immediately below the object are displayed.


12

To show or hide objects below a single object:

• Double-click an object with a plus or minus by it.

To expand or collapse all objects by one level:

• In the lower right corner of the navigator window, select the + or - button.

To hide all objects:

• In the lower right corner of the navigator window, select the - button.

You can use the Database Navigator to select any object in the database. You can also select more than one object to complete a command. You can create a list of selected objects on which to perform options by choosing Select List from the pull down menu at the top of the Database Navigator.

To select a single object:

• In the tree list, click the object and select OK. If the Database Navigator is not in multi-select mode, you can also double-click the object to select it.

To use the mouse to select a continuous set of objects:

1. In the tree list, drag the mouse over the objects you want to select or click on one object, hold down the Shift key, and click the last object in the set. All objects between the two selected objects are highlighted.

2. Select OK.

To use the Up and Down arrow keys to select a continuous set of objects:

1. In the tree list, click on the first object, hold down the Shift key, and then use the Up or Down arrows to select a block of objects.

2. Select OK.

To select a noncontinuous set of objects:

1. In the tree list, click on an object, hold down the Ctrl key, and click on the individual objects you want to select.

2. Select OK.

To clear any selection in the tree list:

• Hold down the Ctrl key and click the selected object to clear its highlighting.

Managing the Select ListYou can use the Database Navigator to view objects you've selected using the procedures explained in Showing, Hiding, and Selecting Objects in the Database Navigator. The list of objects is called the Select list. You can also add and remove objects from the Select list.


To view the select list:

• From the pull-down menu, select Select List.

The selected objects appear in the text box to the right.

To add objects to a select list:

1. From the pull-down menu, select Select List.

2. From the Tree list or Main Window, select the objects to be on the select list as explained in the previous section.

3. Select Add.

4. Select Apply.

To remove objects from the select list:


2. From the list that appears on the right, select the objects to be removed.

3. Select Remove.

4. Select Apply.

To clear all objects from the select list:


2. Select Clear.

3. Select Apply.

Filtering Objects in the Database NavigatorYou can filter the types and names of objects that you want displayed in the Database Navigator to narrow the display to exactly what you want or to broaden the display using wildcards. For example, you can narrow the display to only parts or broaden the display to include all objects that begin with a particular character, such as an h.

To set the filter of the Database Navigator:

1. In the Filter text box, enter the name of the objects that you want to display. Type any wildcards that you want to include.

2. From the pull-down menu, select the type of object or objects that you want to display in the Database Navigator. To select from all the different object types in the modeling database, select Browse.

3. Select OK.


14

Sorting Objects in the Database NavigatorYou can sort objects in the Database Navigator by their name or type, such as parts or geometry. You can also select to not sort the object so the objects appear in the Database Navigator in the order they are stored in the modeling database.

Note that sorting by name can be slow for objects with very long names. Setting no sorting is the fastest way to see objects.

To sort objects in the Database Navigator:

• At the bottom of the Database Navigator, from the Sort by pull-down menu, select how you'd like the objects sorted.

Setting Highlighting in the Database NavigatorYou can set up the Database Navigator so that whenever you select an object in the tree list, it also appears selected in the main window and the reverse. Highlighting is off by default.

To toggle highlighting:

• Select Highlighting.

Setting Appearance of Objects Through the Database NavigatorThrough the Database Navigator, you can set how individual, types of objects, and children of objects appear in your template-based product.

You can set:

• Visibility of the object and of its name on the screen.

• Color, line style, line width and transparency of the object. For example, you can set the color of the object’s outline or its name.

• Size of the screen icons that represent the object in your model. Note that these changes take precedence over the size you specify globally for the modeling database.

• State of the object during a simulation: active or inactive.

To set the appearance of objects:

1. Select an object from the Database Navigator Tree list.


2. Use the options in the dialog box to set the appearance of the object. To inherit an attribute from a parent of the object, select None from any of the pull-down menus. Learn more with Display Attribute dialog box.

3. To set the scope of the appearance changes, you can select either:

• Object - Only apply to the selected object.

• Siblings - Apply changes to all objects of the same type that are children of the parent of the selected object.

• All - Apply changes to objects matching the filter you set in the Filter text box.

4. Select Apply.

Renaming Objects Through the Database NavigatorYou can use the Database Navigator to rename any object.

To rename an object:

1. From the Database Navigator pull-down menu, select Rename.

2. From the Tree list, select the object to rename.

3. In the text box that appears to the right, type a new name for the object.

4. Select Apply.

Adding Comments Through the Database NavigatorYou can use the Database Navigator to associate comments with any object in the Modeling database.

To associate comments with an object:

1. From the Database Navigator pull-down menu, select Comments.

2. From the Tree list or Main Window, select an object.

3. In the text box that appears to the right, type or modify the comments associated with the object.

4. Select Apply.

Tip: For transparency, the higher the value, the more transparent the object is, allowing other objects to show through. The lower the value, the more opaque the object is, covering other objects. However, setting the transparency of objects can have a negative impact on graphical performance if you are using a graphics card without hardware acceleration for OpenGL. Instead of setting an object’s transparency, consider setting the object’s render mode to wireframe.


16

To save the comments in a file:

• Select Save to File.

Viewing Model Topology Through the Database NavigatorThe model topology map displays information about the parts in your model and determines what constraints are owned by the model and what parts the constraints connect. The information appears in the window on the right of the Database Navigator.

You can view the part connection information in the following ways:

• By part - Lists each part in the model, along with the parts it is connected to and what constraints or forces are affecting it. See Model Topology by Part.

• By connections - Displays each constraint and force with the parts they connect and act on. Also displays any unconnected parts. See Model Topology by Connections.

• Graphically - Displays a representation of the selected part and shows its connections to other parts. See Graphically Viewing Model Topology.

To display model topology of parts and connections:

• From the Database Navigator pull-down menu, select Topology by Parts or Topology by Constraints.

To graphically view the topology of parts:

1. From the Database Navigator pull-down menu, select Graphical Topology.


Model Topology by Part

You can select to have your template-based product list each part in the Model, along with the parts it is connected to and what constraints or forces are affecting it. For example, the following shows the information that appears in the Information window or Database Navigator when you display the connections by parts for a model called model_1.

Topology of model: model_1Ground Part: ground

Part groundIs connected to:LINK_1 via JOINT_2 (Revolute Joint)LINK_6 via JOINT_1 (Revolute Joint)LINK_1 via FORCE_1 (Single_Component_Force)

Part LINK_1Is connected to:LINK_5 via JOINT_3 (Revolute Joint)ground via JOINT_2 (Revolute Joint)ground via FORCE_1 (Single_Component_Force)


Part LINK_5Is connected to:LINK_1 via JOINT_3 (Revolute Joint)LINK_6 via JOINT_4 (Revolute Joint)

Part LINK_6Is connected to:LINK_5 via JOINT_4 (Revolute Joint)ground via JOINT_1 (Revolute Joint)

Model Topology by Connections

When you select to display model topology by connection, your template-based product displays each constraint and force with the parts that they connect and act on. Your template-based product also displays any unconnected parts. The following sample shows the information that appears when you select to display topology by connections for a model with three parts, named model_1.

Topology of model: model_1Ground Part: ground

JOINT_1 connects LINK_2 with ground (Revolute Joint)JOINT_2 connects LINK_3 with LINK_4 (Revolute Joint)JOINT_3 connects LINK_2 with LINK_3 (Revolute Joint)

Unconnected Parts: LINK_1

Graphically Viewing Model Topology

In graphical topology, the Database Navigator displays a representation of the selected part and shows its connections to other parts. The connections represent the joints or forces between the parts.


18

Each time you select a different part in the Tree list of the Database Navigator, the graphical display changes to show the select part at its center.

Viewing the Associativity of ObjectsYou can use the Database Navigator to display the objects that a selected object uses. For example, you can select a joint in the Tree list to show the I and J markers that the joint uses. You can also select to view the objects that use the selected object.

To view the associativity of objects:

1. From the Database Navigator pull-down menu, select Associativity.

2. Set the associativity:

• To show the objects that the selected object uses, select Uses

• To show the objects that use the selected object, select Is Used By.

3. From the tree list or Main Window, select an object.

The objects associated with the selected object appear in the text box to the right.

To set up automatic navigation of the objects:

• Select Auto Navigate.


To save the current associativity information to a file:


About Auto Navigation

When you select Auto Navigate, the Database Navigator lets you view the associativity of objects that you select from the Tree list and any objects listed in the window on the right. For example, if you have a model with a joint motion, and then select to view the associativity of that motion, you see a joint listed in the right window, as shown below.

With Auto Navigate selected, you can just select that joint from the right window to view its associativity. If it were not selected, you would have to select the joint from the tree list to view its associativity. In addition, when you select the joint in the right window, the Database Navigator also highlights it in the tree list.

Viewing Object Information Through Database NavigatorYou can use the Database Navigator just as you would use the Information window to display information about an object.


20

To display object information:

1. From the Database Navigator pull-down menu, select Information.


The information about the object appears in the window to the right.

To save the information to a file:


To return to the information about a previous object:

• Select .

Viewing Model Topology Map Through Information WindowThe model topology map displays information about the parts in your Model and determines what constraints are owned by the model and what parts the constraints connect. The information appears in the Information window.

You can view the part connection information in two ways:

• By part - Lists each part in the model, along with the parts it is connected to and what constraints or forces are affecting it. See Model Topology by Part.

• By connections - Displays each constraint and force with the parts they connect and act on. Also displays any unconnected parts. See Model Topology by Connections.

To display model topology by parts, do one of the following:

• From the Tools menu, select Model Topology Map.

• In your template-based product, on the Status Bar, from the Information tool stack, select the

Model Topology by Parts tool .

To display model topology by connections:

• On the status toolbar, from the Information tool stack, select the Model Topology by

Constraints tool .

21Learning the BasicsWorking with the Information Window

Working with the Information WindowYour template-based product uses the Information window to display many different types of information about your model, Simulation, and so on. In addition to just viewing information about your model, you can perform a variety of operations in the Information window. For example, you can display additional information about the current object's parent or child, print the information, display information about a different object in the database, and more.

Displaying Information

• Displaying Object Information and Accessing the Information Window

• Displaying Parent and Children Information

• Displaying an Object's Modify Dialog Box

Managing Information

• Clearing the Information Window

• Saving Information in the Information Window

• Displaying a Text File in the Information Window

• Copying Text in the Information Window

• Setting the Information Mode

Displaying Object Information and Accessing Information WindowYou can display information about each object in your Modeling database, including parts, geometry, motion, and markers. Learn about Markers.

You can view the information about an object currently on the screen or any object in the database, including the Main window or dialog boxes.

When you display information about the objects in your modeling database, your template-based product displays information specific to that type of object. For example, when you display information about a rigid body in your model, your template-based product displays information about its material content, inertial properties, initial conditions, orientation, velocity, and more. When you display information about a motion, your template-based product displays information about the type of motion it is, its function, and time derivative.

To display information about a modeling object displayed on the screen:

• Right-click the object on the screen, and then select Info.

Tip: You may want to zoom in on the object on the screen to more easily place the cursor over just that object.

Adams/CarWorking with the Information Window

22

Information about the object appears in the Information window.

To use the Database Navigator to display information about objects in the Information window:

1. On the Status bar, select the Info tool from the Information tool stack.

The Database Navigator appears.

2. Select the object about which you want to display information. Learn about selecting objects.

3. Select OK.

The information window appears.

To display object information once you've displayed the Information window, do one of the following:

• In the text box at the top of the Information window, enter the name of the object, and then select Apply.

• If the object name already appears in the Information window, place the text cursor in the name of the object, and then select Apply.

Displaying Parent and Children InformationEach object in the database has an object that owns it, called its parent, and many objects own other objects, called their children. The top-level objects in the database are models, plots, and interface objects, called gui objects. These objects do not have parents. You can display information about the parent or children of the object currently displayed in the Information window.

If an object has a parent, the type of parent it has appears in the Information window under the heading Parent Type and the name of the parent is placed in front of the name of the object in the Object Name heading. For example, for the part LINK_2, its parent type and name appear in the Information window, as shown next:

To display an object's children:

• In the Information window, select Children.

To display an object's parent, do one of the following:

• In the Information window, select Parent.

• In the Information window, place the text cursor in the name of the parent and select Apply.


Displaying an Object's Modify Dialog Box from the Information WindowWhen information about an object is displayed in the Information window, you can access that object's modify dialog box so you can modify the object.

To access an object's modify dialog box from the Information window:

• In the Information window, place the text cursor in the name of the object and select Modify.

Clearing the Information WindowEach time you request information in the Information window, your template-based product adds the information to the bottom of the Information window without removing the current information. You can remove all current information.

To clear the Information window:

• In the Information window, select Clear.

Saving Information in the Information WindowYou can save the contents of the Information window to a text file.

To save the contents of the information to a text file:

1. In the Information window, select Save to File.

The Select File dialog box appears.

2. Select the directory in which you want to place the file.

3. In the File Name text box, enter the file name.

4. Select Open.

Displaying a Text File in the Information WindowYou can display any text file in the Information window. You will find this helpful if you want to display an information file that you saved or you are creating a demonstration of your model using a command file and you want to display information about a particular object or aspect of the demonstration.

To display a text file when the Information window is already displayed:

1. In the Information window, select Read from File. dialog box appears.

2. Select the directory in which you want to place the file.

3. Highlight the file that you want to open in the list, or type the file name in the File Name text box.

4. Select Open.

Adams/CarWorking with the Information Window

24

To display a text file when the Information window is not displayed:

1. On the Tools menu, select Show File.

The Info Window Read dialog box appears.

2. In the File Name text box, you can either:

• Enter the name of the file.

• Browse for a file: right-click the File Name text box, and then select Browse to display the File Selection dialog box.

3. Select OK.

The Information window appears with the text of the file as its content.

Copying Text in the Information WindowYou can copy any text in the Information window for use in another window, dialog box, or application. You cannot paste or delete any text in the window.

To copy text in the Information window:

1. Highlight the text that you want to copy.

2. Right-click the Information window and select Copy.

Setting the Information ModeBy default, the Information window displays only a part's parent and type. To display more information about the part, you can turn on verbose mode. When you turn on verbose mode, the Information window displays the children of the object, its geometry, whether or not comments are associated with it, and its attributes, such as its color and visibility.

To turn on verbose mode:

• Select the Verbose check box.

Using WildcardsYou can use wildcards to narrow any search, set the type of information displayed in a window, such as the Database Navigator or the Log file, or specify a name of an object in a dialog box.

This Character:

* (asterisk) Zero or more characters

? Any single character

[ab] Any one of the characters in the brackets


Tips on Using Wildcards

Here are some tips for entering wildcards:

• Case is insignificant, so xYz is the same as XYz.

• You can match alternative sequences of characters by enclosing them in braces and separating them with commas. For example, the pattern a{ab,bc,cd}x matches aabx, abcx, and acdx.

• You can form character sets that match a single character using brackets [ ]. For example, [abc]d matches ad, bd, and CD

• You can use a dash (-) to create ranges of characters. For example, [a-f1-4] is the same as [abcdef1234].

• You can use a backslash (\) to include a special character as part of the character set. For example, [AB\]CD] includes the five characters a, b, ], c, and d.

Here are some examples of more complex patterns and possible matches:

• x*y - Matches any object whose name starts with x and ends with y. This would include xy, x1y, and xaby.

• x??y - Matches only those objects with four-character long names that start with x and end with y. This would include xaay, xaby, and xrqy.

• x?y* - Matches all of those objects whose names start with x and have y as the third character. This would include xayee, xyy, and xxya.

• *{aa,ee,ii,oo,uu}* - Matches all those objects whose name contains the same vowel twice in a row. This would include loops and skiing.

• [aeiou]*[0-9] - Matches any object whose name starts with a vowel and ends with a digit. This would include eagle10, arapahoe9, and ex29.

• [^aeiou]?[xyz]* - Matches any object whose name does not start with a vowel and has x, y, or z as the third letter. This would include thx1138, rex, and fizzy.

[^AB] Any character other than the characters following the caret symbol (^) in the brackets

[a-c] Any one character in a range enclosed in brackets

{AB, bc} Any of the character strings in the braces

This Character:

Adams/CarSetting Preferences

26

Setting Preferences

Setting Screen and Printer FontsYou can change the font your template-based product uses to display text in a view, such as the name of a part or a note on the screen, or to print text to a printer. The fonts available for displaying text in a view are those available with your operating system. The fonts available for printing text are a fixed set of 12 fonts. Note that your printer may not support all of these printer fonts. Learn about Printing Models.

To select a screen or printer font:

1. On the Settings menu, select Fonts.

The Fonts dialog box appears.

2. In the Screen Font text box, enter the name of the font you want your template-based product to use to display text in a view. To browse for a font, right-click the text box, select Browse, and then select a font.

3. Set Postscript Font to the font you want to use to print text.

4. Select OK.

Specifying Working Directory By default, your template-based product searches for and saves all files in the directory from which you ran your template-based product. You can change the working directory.

To change the working directory for the current session:

1. On the File menu, select Select Directory.

Select the directory in which your template-based product should save files.

2. Select OK.

You can also set the working directory when you start your template-based product. Learm about Starting a New Modeling Session.

To change the working directory for all sessions:

On UNIX:

1. From the Adams Toolbar, right-click your template-based product's tool, and then select Change Settings.

2. In the Registry Editor, select WorkingDirectory, and then change the working directory.

For more information see Running and Configuring Adams.

On Windows:

1. On the Desktop, right-click your template-based product's shortcut, and select Properties.

27Learning the BasicsSetting Preferences

2. In the Start In text box, enter the working directory.

For more information, see your Windows online help.

Setting Units of Measurement You can set the units that your template-based product uses in modeling, importing, and exporting files. You can select individual units or select a set group of units. Learn about Units of Measurement in Adams/View.

To set the unit of measurement:

1. On the Settings menu, select Units.

The Units Settings dialog box appears.

2. Select the unit of measurement for each of the dimensions using the table below for assistance.

3. Select OK.

To Select: Do the following:

Unit for a specific dimensions

Select the individual unit from the pull-down menu associated with the dimension.

Predefined unit system

Select one of the following buttons. In all the unit systems, time is in seconds and angle is in degrees. When you select a predefined unit system, the units selected appear in the upper portion of the dialog box.

• MMKS - Sets length to millimeters, mass to kilograms, and force to Newtons.

• MKS - Sets length to meters, mass to kilograms, and force to Newtons.

• CGS - Sets length to centimeters, mass to grams, and force to Dyne.

• IPS - Sets length to inches, mass to pound mass, and force to PoundForce.

Adams/CarSetting Screen Icon Display

28

Setting Screen Icon DisplayWhen you first start your template-based product, it displays Screen icons. As you add objects to your model, however, these icons can clutter your view of the model. To clear the display of a window, you can turn off the icons. You can select to turn off:

• All icons

• Only icons of certain types of objects, for example, all joints

• Only icons for individual objects, such as FORCE_1

In addition, you can set the size of the icons either in current units or as a factor of their current size.

Learn more about how to set the display of screen icons by database and object type.

• Setting Screen Icon Display by Database

• Setting Screen Icon Display by Object Type

For information on quickly toggling the display of all screen icons, see Displaying View Accessories. For information on setting the display of icons for individual objects, see Setting Object Appearance through Edit -> Appearance Command.

Setting Screen Icon Display by DatabaseYou can set up how you want Screen icons to be displayed for an entire Modeling database. By default, all models and objects in the modeling database inherit the screen icon settings that you specify for the database. You can, however, override the inheritance for different types of objects as explained in Setting Screen Icon Display by Object Type, or for individual objects as explained in Setting Object Appearance through Edit -> Appearance Command.

To set up the screen icon display for the entire database:

1. On the Settings menu, select Icons.

The Icon Settings Dialog Box appears.

2. Set New Value to one of the following to select whether or not you want to turn on screen icons:

• No Change - Select No Change to not change the current settings.

• On - Turns on all icons regardless of how you set the icon display for individual objects or types of objects.

• Off - Turns off all icons regardless of how you set the icon display for individual objects or types of objects.

3. In the New Size text box, enter the size you want for the screen icons. Note that any changes you make to the size of icons for individual objects or types of objects take precedence over this size setting.

4. To save the settings for each new database in your template-based product settings file (*BS.cmd), select Save new size as default. Learn about Saving and Restoring Settings.

29Learning the BasicsSetting Screen Icon Display

5. Select OK.

To reset the screen icon display to the previous values:

• On the Icon Settings dialog box, select Reset.

Setting Screen Icon Display by Object TypeYou can set up how you want Screen icons displayed for a particular type of object, such as all parts or joints. By default, all objects inherit the screen icon display options that you specify for the modeling database. You can set screen icon options for the following types of objects:

• Part (also called Bodies)

• Joints

• Forces

• Motion

• Markers (Note that markers belong to parts and, therefore, by default, inherit screen icon display options for parts.)

• Points

• Data elements

• Equations (System elements)

To set screen icon display options for objects of a particular type:

1. On the Settings menu, select Icons.

The Icon Settings Dialog Box appears.

2. Set Specify Attributes for to the type of object for which you want to set the screen icon options.

3. From the Visibility area of the Icon Settings dialog box, select whether or not you want to turn on screen icons for the selected object type. You can select:

• On - Turns on the display of screen icons for the selected type of object.

• Off - Turns off the display of screen icons for the selected type of object. Remember, however, that turning on the display of screen icons for the entire database overrides this setting.

• Inherit - Lets the object type simply inherit the display settings from its parent. For example, a coordinate system marker inherits settings from its parent part.

• No Change - Does not change the current settings. Lets you make changes to other display options without affecting the visibility of the icons.

4. Enter the size you want for the icons or select the amount by which you want to scale the icons. The scale factor is relative to the current size set. A scale factor of 1 keeps the icons the same size. A scale factor less than 1.0 reduces the size of the icons and a scale factor greater than 1.0 increases the size of the icons. Note that these changes take precedence over the size you specify globally for the modeling database.

5. Enter the color you want to use for the icons.

Adams/CarSetting Screen Icon Display

30

6. To browse for or create a color, right-click the Color text box, and then select Browse or Create.

7. Set Name Visibility Option to whether or not you want the names of objects of the selected type displayed in the view. Refer to Step 3 for an explanation of the choices.

8. Select OK.

31Learning the BasicsSetting Display Options

Setting Display OptionsLearn about:

• Setting Part Display

• Displaying View Accessories

• Setting Rendering Mode

• Displaying the Status Toolbar

Setting Part DisplayYou can set the Main window so it displays a particular part in the current Model. You will find this helpful when you want to compare or work with different parts at the same time.

To display a single part in the main window:

1. Click the main window.

2. From the View menu, select Part Only.

The Database Navigator appears listing the parts in the current model.

3. Select the part you want to display.

4. Select OK.

The selected part appears in the currently active view.

Displaying View AccessoriesWhen you first start your template-based product, it displays several accessories to help you manage the view of your model:

• Working grid

• Screen icons

• View triad

• View title

To use a dialog box to toggle on and off the display of view accessories:

1. Click the Main window.

2. On the View menu, select View Accessories, and then select the accessories that you want to turn on or off from the View Accessories dialog box that appears.

3. Enter the title you want displayed in the main window, and then press Enter.

Adams/CarSetting Display Options

32

4. On the Window menu in the View Accessories dialog box, select Exit.

Setting Rendering ModeYour template-based product provides six Rendering modes in which you can display a model in the Main window.

To select a rendering mode:

• Click the main window.

• On the View menu, point to Render Mode, and then select a rendering mode.

To toggle the display between wireframe and smooth shaded mode:

• Type an uppercase S in the main window.

Displaying the Status ToolbarYou can turn on and off the display of the Status bar. You can also set where the status toolbar appears—either at the top of the main window under the menu bar or at the bottom of the window. By default, the status toolbar appears at the bottom of the window.

To turn the status toolbar on and off:

1. On the View menu, select Toolbox and Toolbars.

2. Select Status Toolbar and its placement in the main window. Your changes take place immediately.

3. Close the dialog box.

Refreshing the Model DisplayYou can redraw the Main window to return the model to its initial configuration and display all geometry in the Model . This is particularly useful if you selected to view only certain parts and now want to view the entire model.

To refresh the model display:

• On the View menu, select Refresh.

Tip: • Type a lowercase g while the cursor is in the main window to toggle on and off the display of the working grid.

• Type a lowercase v to toggle on and off the display of screen icons.

33Learning the BasicsSetting View Background Colors

Setting View Background ColorsBy default, your template-based product uses a blue background to display the Main window. It also provides a set of colors in which you can display the background. You can set the view to any color by setting the red, green, and blue colors directly.

Selecting a Preset Background ColorYou access the palette of background colors using View Background Color command on the Settings menu.

To select from the entire palette of background colors:

1. From the Settings menu, select View Background Colors.

2. Press F1 and then follow the instructions in the dialog box help for Edit Background Color.

3. Select OK.

Creating a Background ColorYou can create a background color by setting its red, green, and blue light percentages and change the background of the Main window to this new color. You cannot add the color to the preset palette of colors or change the colors in the preset palette.

To create a color:

1. From the Settings menu, select View Background Colors.

2. Press F1 and then follow the instructions in the dialog box help for Edit Background Color.

3. Select OK.

To reset a color to the original background color:

• Select the R tool in the Edit Background Color dialog box.

Adams/CarUsing Template-Based Product Tools

34

Using Template-Based Product ToolsLearn about using the following template-based product tools:

• Coordinate Window

• Command Navigator

• Command Window

• Message Window

• Information Window

• Database Navigator

Working with the Coordinate WindowYou can use the Coordinate window to help you identify the coordinates of any location in the Main window. You can also measure the distance between objects based on their coordinate locations.

The sections below explain how to work with the coordinate window:

Displaying the Coordinate Window

To toggle on and off the display of the coordinate window, do one of the following:

• On the View menu, select Coordinate Window.

The coordinate window appears in the lower right corner of the screen. You can move and size it as you do any window in your operating system.

Measuring the Distance Between Points

In Delta mode, you can use your mouse and the coordinate window to find the distance between two points.

To measure the distance between two points:

1. Move the cursor to the point in the main window where you want to begin, and press and hold down the mouse button.

2. Drag the cursor to the next point. As you drag the cursor, your template-based product displays the distance the cursor moves in the coordinate window.

3. To end delta mode, release the mouse button.

Tip: Press the F4 key to toggle the display of the coordinate window.

35Learning the BasicsUsing Template-Based Product Tools

Command NavigatorEnables you to enter Adams/View commands without having to know the entire syntax of the commands. See Command Navigator dialog box help.

The Command Navigator displays a list of all Adams/View command Keywords. A plus (+) in front of a keyword indicates that the command has more keywords below it but they are hidden. A minus (-) indicates that all keywords below the keyword are displayed. No indicator in front of a keyword indicates that there are no more keywords below the object. When you select an object with no indicator, a dialog box appears in which you enter parameters for executing the command.

Using the Command WindowThe command window provides a text-based way to enter commands. It assumes that you understand the command language underlying your template-based product's interface. The command window contains both a command entry area for entering commands and a command information area for displaying informational and error messages:

Learn about using the command window:

• About Commands

• Syntax Rules for Entering Commands

• Syntax Rules for Entering Values

• Miscellaneous Command Information

• Getting Help Completing Command Parameters

• Grouping Operations into an Undo Block


36

About Commands

The commands that you enter in the command window or Command Navigator are made up of keywords, parameters for the keywords, and parameter values as shown next:

{keywords} {parameters=values}

In a command:

• Keywords correspond to menu selections.

• Parameters correspond to dialog box choices.

• Parameter values correspond to values you enter or select in the dialog boxes.

For example, the following command contains the keyword constraint followed by other keywords, then by parameters, such as the name of the joint. In the example, an ! indicates a comment and an & at the end of a line indicates that the command continues onto the next line.

constraint create joint revolute & !{keywords}joint_name=.model_1.JOINT_1 & !{parameter=value}i_marker_name=.model_1.PART_1.MAR_3 & !”&” for continuationj_marker_name=.model_1.ground.MAR_1 &friction_enabled = no

Syntax Rules for Entering Commands

There are several rules that you must follow when you enter commands in the command window. For example, the commands must be entered in the order shown below. Because commands are case insensitive, you can type upper or lowercase letters or a mix of both.

To help you enter commands correctly, your template-based product checks for syntax errors whenever you enter a space, comma, or equal sign (except in a string or expression) in the command window. If it detects an error, it displays a message above the command information area. You cannot proceed until you correct the error.


Syntax Rules for Entering Values

The values that you can enter in commands are data that have a particular type. There are five data types that template-based product commands support: integer, real, string, matrix, and database object references. The following table lists the data types and their use.

The rules for entering values are that they:

• Can contain letters, numbers, and underscore characters.

• Must begin with a letter or underscore character.

• Can contain any characters that are enclosed by double quotation marks.

• Have separators (blank space or tab) between keywords and parameters. Placing separators between parameters and their values is optional.

For strings, you must use a backslash (\) in front of special characters to ensure that your template-based product does not try to interpret the characters. These characters include quotation marks (") and backslashes. For example, to be sure to include the quotation marks in the string: This is a "string", you would enter:

string "This is a \"string\"."

To get a single backslash into the string, you, therefore, enter double backslashes. For example, to specify d:\users, you would enter:

"d:\\users..."

Note also for path names on Windows, you can use backslashes as the separators, but you are not required to do so. You can write portable path names by using the forward slash so your template-based product interprets the following as the same path:

"d:\\users\\efhl\\some.file""d:/users/efhl/some.file"

Data type: Use:

Integer Whole numbers in the range -maxint ... +maxint, where maxint is machine dependent (usually around two billion)

Real Most numeric values

String Character strings of varying length

Object Database objects


38

Miscellaneous Command Information

Continuing Commands

You can continue a command you enter in the command window for as many lines as necessary. To continue a command, place an ampersand (&) at the end of a line and then continue the command on the next line. Note that a command must be entered all at once.

Mixing Comments and Commands

If you want to mix comments and commands (so that your comments appear in the Log file), use one of the formats below:

Entering Abbreviations

You can enter abbreviations for commands and parameters when you are entering commands directly in the command window. You should always use full keywords for macros and command files to avoid any future compatibility problems. Also note that if you use abbreviations, your template-based product takes longer to execute your commands because it must substitute an abbreviation with its full command.

Verifying Command Input

Your template-based product verifies command input whenever you enter a space, comma, or equal sign (except in a string or expression) in the command window. If your template-based product detects an error, it displays a message above the command information area. You cannot proceed until you correct the error.

Reviewing Commands

You can use the scroll bar at the side of the command information area to view the last 50 commands that were entered.

To create: Enter:

A comment alone on one line !comment <CR>

A command followed by a comment on one line command !comment<CR>

A command followed by a comment on one line, with the command continuing on the next line command

&!comment<CR>continuecommand

A command followed by a comment on one line, with the comment continuing on the next line, and the command continuing on the following line command

&!comment<CR>&!comment<CR>continuecommand


Getting Help Completing Command Parameters

In the command window, you can get help with possible parameter values for modeling objects and files. For example, you can get a list of possible marker names in your model or you can display the File Browser to help you find a file. Learn about Markers.

To get assistance with values for a parameter:

1. Enter the parameter name but do not include the parameter value. For example, enter the command mar del mar=.

2. Type ? in the command line.

If the parameter value requires a modeling object, the command window displays a list of possible objects in your current model. If the parameter value requires a file, the File Browser appears.

3. Copy or select the desired object and place it in the parameter value.

Grouping Operations into an Undo Block

As you issue commands from the command window, you can group them into undo blocks. By grouping them into undo blocks, you can use a single Undo command to reverse all the operations in the block. You can define undo blocks around macros, command files, or any group of commands. You can nest them to any level.

To create an undo block:

1. Enter the following command in the command window to mark the beginning of the block:

UNDO BEGIN_BLOCK

2. Issue all the commands to be included in the undo block.

3. To close the block, enter the command:

UNDO END_BLOCK

Once you have closed the undo block, any individual commands that you issue that are not in the undo block or any nested undo blocks within the undo block are not affected by an Undo command. Once you close the undo block, you cannot open it again.

The following is an example of an undo block with individual commands surrounding it and several undo operations that were issued. The undo commands reverse all operations that were performed to create the model and part.

MODEL CREATE...UNDO BEGIN_BLOCKPART CREATE...MARKER CREATE...UNDO BACKWARD ! Undo the MARKER CREATE above, not entire undo blockMARKER CREATE...GEOM CREATE...UNDO END_BLOCKPART DELETE...


40

UNDO BACKWARD ! Undo the PART DELETE commandUNDO BACKWARD ! Undo the entire undo blockUNDO FORWARD ! Restore the entire undo blockUNDO BACKWARD ! Undo the entire undo block againUNDO BACKWARD ! Undo the MODEL CREATE command

Note the following about the example:

• The first UNDO BACKWARD within the undo block undoes only the preceding MARKER CREATE command.

• The third UNDO BACKWARD command after the Undo block undoes the entire contents of the undo block.

• The UNDO FORWARD reverses the undo of the entire undo block as if the undo block were a single command.

The limit on the number of commands your template-based product remembers does not apply to commands within an undo block. You may notice slowed system performance if you store too many commands in a single undo block.

Message WindowProvides you with messages on the status of Adams/View and displays helpful information while you are using Adams.

Adams/View displays messages about the execution of a command in the message window. By default, the message window only displays messages about commands you execute from the user interface. You can also set it to display messages about commands that you execute from the Command window, Command Navigator, and Adams/View command files.

Learn about Managing Messages.

Information WindowAdams/View uses the Information window to display many different types of information about your model, simulation, or motion data. In addition to just viewing information about your model, you can perform a variety of operations in the Information window.

The information includes:

• Topology on the different objects in your model

• Object information, such as information about a part or a view

• Model verification results

• Measurements from one coordinate system marker to another

• Result set component information

• View attributes

• Results from a system command you run using the Tools -> System Command


Learn about:

• Displaying Object Information and Accessing Information Window

• Viewing Model Topology Map Through Information Window

• Verifying Your Model

Database NavigatorDisplays the types of objects appropriate for the command you are executing and shows objects in their database hierarchy. You can browse for objects or set it to rename objects, view information about the objects and view dependencies. You can also set a filter for the types of objects displayed in the Database Navigator.

The Option: Does the following

Apply Executes the command but leaves the dialog box open so you can execute the command again.

Parent Displays an object's parent.

Children Displays an object's children.

Modify Select to display the modify dialog box for the object displayed in the text box at the top of the Information window.

Verbose Select if you want to display more information about the object such as children of the object, its geometry, whether or not commands are associated with it, and its attributes like color and visibility.

Clear Removes all current information in the window.

Read from File Allows you to read information from a saved file.

Save to File Allows you to save the information.


42

Learn more about Database Navigator.

For the option: Do the following:

Pull-Down Menu Use the pull-down menu to choose a mode option. Select one:

• Browse (the default; the options on this page describe Browse)

• Display Attribute

• Rename

• Comments

• Information

• Topology By Parts

• Topology By Connections

• Graphical Topology

• Associativity

• Select List

Filter Select if you want to filter the types and names that you want displayed in the Database Navigator. Then, enter the name of the objects you want to display in the text box and use the pull-down menu to the right to select the type of object(s) you want to display. You can also use the pull-down menu below the Filter text box to only display those objects that are active or inactive.

Sort by Use the pull-down menu to choose how you want the objects sorted. You can also select to not sort the objects so they appear in the order they are stored in the modeling database.

Highlight Off by default. Select if you want an object to appear selected in the main window and the reverse.

Use the plus sign (+) or the minus (-) (--) signs to display or hide all of the children hidden/shown in the tree view.

43Learning the BasicsFiles and Commands

Files and Commands

Executing a System CommandYou can execute an operating system command from within your template-based product so that you do not have to leave your template-based product window.

You can select to display the results of the command in the Information window or the Log file. If you select to display the results of the command in the Information window, you can:

• Clear the window and only view the results of the command.

• Save the results of the command to a file.

If you select to display the results in the log file, you can keep the command results with the other commands that you execute so that you can cut and paste the information together into a new file.

To execute a system command within your template-based product:

1. On the Tools menu, select System Command.

The Execute System Command dialog box appears.

2. In the Command Text text box, enter the operating system command that you want to execute. See your operating system documentation for more information.

3. Select whether or not you want the output of the command to be displayed in the Information window or the log file.

4. Select OK.

Using the Log File Your template-based product generates a log file during each session, called *.log.

While you are running Adams, you can display the current contents of the log file. In addition, you can display the log file in a text editor. The following sections explain how to display the log file in your template-based product and set the type of messages displayed.

• Viewing the Log File in Your Template-Based Product

• Updating the Log File

• Setting the Log File Information

Note: You can change the name of the log file through the initialization file .mdi_init. For more information, see Running and Configuring Adams.

Adams/CarFiles and Commands

44

Viewing the Log File in Your Template-Based Product

You can use the Log File command on the Tools menu to display the log file. You can keep the dialog box open as you execute commands so you can keep track of the commands and messages that you receive.

To help you use the log file as a command file, your template-based product marks any messages as comments so that it does not try to execute them when you import the command file. It indicates a comment by placing an exclamation mark (!) in front of the message. Your template-based product also displays as comments any commands that it executes when it starts up. To help you distinguish the startup commands from messages, your template-based product follows the exclamation mark (!) with the command prompt (>>).

To display the log file:

1. On the Tools menu, select Log File.

The Display Log File dialog box appears.

2. Select Info to display all messages written to the log file. The default is to display only warnings, errors, and fatal messages.

Updating the Log File

Your template-based product does not update the Display Log File dialog box each time you execute a command. Therefore, if you want to see the commands that you executed since you opened the dialog box, you must update the log file.

To update the contents of the log file:

• From the Display Log File dialog box, select Update.

Setting the Log File Information

When you display the log file, your template-based product displays only warnings, errors, and fatal messages that you have received. You can change the type of messages that your template-based product displays as well as display the commands that your template-based product has executed. You can also display only lines that contain certain information, such as display only commands that create links, and remove any duplicate lines that occur if you encounter the same error again.

To set the type of information displayed in the Display Log File dialog box:

1. Select the Show only lines of type check box and then select one of the following:

• Info - Displays all commands that you have executed in your template-based product.

• Warning - Displays non-fatal messages that warn you of possible problems with commands you entered.

• Error - Displays fatal messages that your template-based product did not understand and, therefore, did not successfully process.

• Fatal - Displays messages that indicated that your model would not simulate.

45Learning the BasicsFiles and Commands

2. If desired, select Show only lines containing and enter the text that the line must contain in the text box. You can also enter wildcards.

3. Select Apply.

To remove duplicate lines:

• From the Display Log File dialog box, select Suppress duplicate lines.

Loading and Unloading PluginsMSC has many add-on modules or plugins to template-based products, which expand their functionality. The plugins include Adams/Driveline, Adams/Car Ride, Adams/Vibration, Adams/Controls, and Adams/Durability. You run these products from within your template-based product. You can set your template-based product to load them automatically when you start up. You can also unload them while in your template-based product's current session. To run a plugin, you must have a license to it.

To see if there is a license available to run a plugin:

1. From the Tools menu, select Plugin Manager.

The Plugin Manager appears.

2. At the top of the Plugin Manager, select a plugin.

3. At the bottom of the Plugin Manager, in the text box Licenses, view the number of licenses available.

To load an available plugin:


2. In the Load column, next to the plugins you want to load, select Yes.

3. Select OK.

The commands or menus for the plugins are added to your template-based product.

To unload a plugin:


2. In the Load column, next to the plugin you want to unload, clear the selection of Yes.

3. Select OK.

Your template-based product removes any plugin menus or commands.

To set up a plugin so it loads automatically when you start your template-based product:


2. In the Load at Startup column, next to the plugin you want to load automatically, select Yes.

3. Select OK.

Adams/CarFiles and Commands

46

Displaying Product InformationWhen using any Adams product, you can display the following information:

• Software version number and the date it was built

• Directory where Adams is installed

• Copyright statement

To display information about your product:

1. From the Help menu, select About <product name>.

2. View the information, and then select OK.

Tip: From the Status bar, select .

Building Models

Adams/CarSubsystems

48

SubsystemsYou only use subsystems in the Standard Interface. You can either create new subsystems or read in existing ones. When you create a new subsystem, you must reference an existing template. When you use an existing subsystem, the template associated with it is automatically read in.

Subsystems are based on templates and allow standard users to change the parametric data of the template as well as the definition of some of the components. For example, you can change the location of hardpoints and modify parameter variables. See Generating a Subsystem.

The template-based products organize the basic components that make up a full assembly or subassembly into subsystems. For example, subsystems can include suspensions, wheels, drivelines, chassis, and so on.

Subsystems contain descriptions of the component that they model. These descriptions consist of:

• Design data, such as wheel radii, toe angles, and locations of various points in the subsystems, named hardpoints, mass properties of parts, and so on.

• References to property files that contain design data for bushings, bumpstops, dampers, engines, springs, and tires. A bushing property file, for example, contains a description of the bushing's stiffness and damping characteristics.

• Reference to a template that defines the subsystem's construction, including the kinds of parts and how the parts interact and attach to one another. For example, a template that defines a rack and pinion steering system defines a rack part, a pinion part, and a housing part. It also defines that the rack slides in the housing, that the pinion rotates in the housing, and that the rack and pinion are geared together. Since the construction of all rack and pinion steering systems is similar, all subsystems describing a rack and pinion steering system can reference the same template.

Learn more about subsystems:

• Opening Subsystems

• Getting Subsystem Information

• Creating Subsystems

• Updating Subsystems

• Synchronizing Subsystems

• Adding Subsystems

• Replacing Subsystems

• Removing Subsystems

• Setting Subsystem Activity

• Saving Subsystems

• Closing Subsystems

• Subsystem Modes

49Building ModelsSubsystems

• Minor Roles

• Publishing Subsystems

Opening SubsystemsWhen you open a subsystem that specifies a flexible representation of a rigid part, your template-based product replaces the equivalent rigid body from the template with the flexible body. Learn about flexible bodies.

To open an existing subsystem:

1. In Standard Interface, from the File menu, point to Open and then select Subsystem.

2. Press F1 and then follow the instructions in the dialog box help for Open Subsystem.

3. Select OK.

Notice that once the subsystem is open, the Edit and Adjust menus become active. We recommend that you familiarize yourself with each menu item.

Getting Subsystem InformationYou can get detailed information about subsystems in the current session.

To get information about a subsystem:

1. In the Standard Interface, from the File menu, point to Info, and then select Subsystem.

2. Press F1 and then follow the instructions in the dialog box help for Subsystem Info.

3. Select OK.

Creating SubsystemsYou create subsystems by selecting a template that defines the topology and default data for your subsystem. Using the Standard Interface, you can modify the default data to match your design. We supply several templates with each product. For example, for Adams/Car users, we supply templates that represent MacPherson strut and double-wishbone suspension subsystems. Using the Template Builder you can create templates for your company-specific topologies.

When creating a new subsystem, you can reference the property files that the template references, or reference other property files held either in a different database or with a different file name, as indicated by the dashed lines in the Example Model Architecture. A collection of subsystems merged together forms an assembly.

To create a subsystem:

1. In the Standard Interface, from the File menu, point to New, and then select Subsystem.

2. Press F1 and then follow the instructions in the dialog box help for New Subsystem.

Adams/CarSubsystems

50

3. Select OK.

Updating SubsystemsResets the values of a subsystem to those stored in a subsystem file. You can update a subsystem using any subsystem file that is based on the same template as the subsystem in session.

When you update a subsystem, your template-based product does not reload the template.

To update a subsystem:

1. In the Standard Interface, from the File menu, point to Manage Subsystems, and then select Update.

2. Press F1 and then follow the instructions in the dialog box help for Update Subsystem.

3. Select OK.

Synchronizing SubsystemsWhen you synchronize a subsystem, you apply the values of the selected master subsystem to one or more subsystem instances using the automated subsystem update feature. You can synchronize the subsystems in session that are based on the same subsystem file. The subsystem mode flags (kinematic or compliant) of the target subsystems will be retained.

For example, you may have several instances of one subsystem open in your session under several assemblies. If you modify one subsystem and want to propagate those changes to every instance of the subsystem, you can use the synchronize subsystems functionality.

To synchronize subsystems:

1. In the Standard Interface, from the File menu, point to Manage Subsystems, and then select Synchronize.

2. Press F1 and then follow the instructions in the dialog box help for Synchronize Subsystem.

3. Select OK.

Adding SubsystemsWhen you add a subsystem into an assembly, your template-based product disassembles the assembled model, opens the subsystem, and then reassembles the model to include the new subsystem.

To add a subsystem:

1. From the File menu, point to Manage Assemblies, and then select Add Subsystem.

Note: The subsystems is not renamed during the update.


2. Press F1 and then follow the instructions in the dialog box help for Add Subsystem.

3. Select OK.

Your template-based product does the following:

• Disassembles the assembly, which includes 'unassigning' communicators.

• Opens the new subsystem under the existing assembly.

• Reassembles the assembly, which includes re-assigning the communicators.

Replacing SubsystemsWhen you replace a subsystem in an assembly with a new subsystem, your template-based product disassembles the assembled model, deletes the subsystem, opens the new subsystem, and then reassembles the model to include the new subsystem.

To replace a subsystem:

1. From the File menu, point to Manage Assemblies, and then select Replace Subsystem.

2. Press F1 and then follow the instructions in the dialog box help for Replace Subsystem.

Select OK.



• Deletes the subsystem from the existing assembly.

• Opens the new subsystem underneath the existing assembly.


Removing SubsystemsWhen you remove a subsystem from the assembly to which it belongs, your template-based product disassembles the assembled model, deletes the subsystem, and then reassembles the model.

To remove a subsystem:

1. From the File menu, point to Manage Assemblies, and then select Remove Subsystem.

2. Press F1 and then follow the instructions in the dialog box help for Remove Subsystem.

3. Select OK.



• Deletes the subsystem from the assembly.


Adams/CarSubsystems

52

Toggling Subsystem ActivityToggles the activity status of an existing subsystem. Your template-based product disassembles the assembled model, sets the subsystem activity accordingly, and then reassembles the model to take into account the subsystem’s activity status.

When you set the subsystem activity status to inactive, your template-based product ignores the subsystem during model assembly, and will not write it to the Adams/Solver files.

Note that compared to the Remove Subsystem functionality, which deletes the subsystem, the Toggle Subsystem Activity functionality only de-activates the subsystem and all objects in it.

To toggle subsystem activity:

1. From the File menu, point to Manage Assemblies, and then select Toggle Subsystem Activity.

2. Press F1 and then follow the instructions in the dialog box help for Toggle Subsystem Activity.

3. Select OK.

If activating the subsystem, your template-based product does the following:


• Activates the subsystem, which means that it will now be considered a valid part of the assembly.

• Reassembles the assembly (with the activated subsystem now taking part), which includes re-assigning the communicators.

If deactivating the subsystem, your template-based product does the following:


• Deactivates the subsystem, which means that it is not actually removed from the assembly, but simply ignored.

• Reassembles the assembly (with the deactivated subsystem not considered), which includes re-assigning the communicators.

Saving SubsystemsYou save subsystems in ASCII format, and you can publish subsystems to databases so other users can share them. We support two formats: TeimOrbit File Format and XML File Format.

If your subsystem contains a flexible part, your template-based product saves information about the part, as well as the marker-node association, in the PART_ASSEMBLY block of the subsystem file. Your template-based product writes one block for a single flexible part or two for paired parts, of which one is flexible.

To save a subsystem:

• While viewing a subsystem, from the File menu, do one of the following:


• Select Save (or use the keyboard shortcut, Ctrl + s) - Your template-based product saves the TeimOrbit version of the subsystem to the default writable database and prompts you if a subsystem already exists. For save options, select Save As.

• Point to Save As, and then select Subsystem - Press F1 and then follow the instructions in the dialog box help for Save Subsystem. Select OK.

To save a subsystem that is part of an assembly:

1. View the subsystem you want to save:

• From the View menu, select Subsystem.

• Set Subsystem to the subsystem you want to save.

• Select OK.


• Select Save (or use the keyboard shortcut, Ctrl + s) - Your template-based product saves the TeimOrbit version of the subsystem to the default writable database and prompts you if a subsystem already exists. For save options, select Save As.

• Point to Save As, and then select Subsystem - Press F1 and then follow the instructions in the dialog box help for Save Subsystem. Select OK.

Closing SubsystemsYou can close a subsystem without first saving it to a Database.

To close a subsystem:

1. In the Standard Interface, from the File menu, point to Close, and then select Subsystem.

2. Press F1 and then follow the instructions in the dialog box help for Close Subsystem.

3. Select OK.

Subsystem ModesA subsystem exists in one of two modes - kinematic or compliant. When you toggle a subsystem between these two modes, certain elements such as joints and bushings may be enabled or disabled. When you create a joint, you define it to be active always or only in kinematic mode. Conversely, when you create a bushing, you define it to never be inactive or be inactive only in the kinematic mode. This allows you to use the same subsystem for both Dynamic Analysis and Kinematic Analysis.

Minor RolesYou assign a minor role, or function, to every subsystem. The minor role of a subsystem is stored in a variable as a string. This string will also be written to the subsystem file. You select a minor role to

Adams/CarSubsystems

54

identify how your product should use the subsystem when creating an assembly of subsystems for Analysis.

A minor role defines the subsystem's location.

• Adams/Car - A minor role can be front or rear. The following are the minor roles for Adams/Car: any, front, rear, and trailer.

If you create a new subsystem with the minor role front based on a steering template, during assembly Adams/Car connects your front steering subsystem to a front suspension subsystem, but not a rear suspension subsystem.

If you create a new subsystem with the minor role any, during assembly Adams/Car connects your new subsystem to any other active subsystem having matching communicators.

Publishing SubsystemsWhen you publish a subsystem, you copy the subsystem file and all its associated property files to the target database, which is the database where your template-based product saves all files. You can also select to publish the subsystem's template file. As you publish the subsystem, you can choose to write over existing files or create backups of the files.

You can also select to update the in-session subsystem data to point to the target database or to have the subsystem retain the existing references.

The subsystem you are publishing must be currently opened in the standard interface, and the target database must be writable. Learn about setting the writable database.

You can also publish an entire assembly. Learn about publishing an assembly.

To publish a subsystem:

1. From the Tools menu, point to Database Management, and then select Publish Subsystem.

2. Press F1 and then follow the instructions in the dialog box help for Publish an Open Subsystem.

3. Select OK.

55Building ModelsAssemblies

AssembliesAssemblies represent a collection of subsystems, along with a test rig, which when assembled form a system that you can analyze using Adams/Solver.

In Adams/Car for example, a steering subsystem and a front-suspension subsystem, plus a suspension test rig, form the basis of a suspension assembly that you can analyze for kinematic behavior.

In the Standard Interface, you can create, open, save, and analyze assemblies. You can also publish assemblies to databases so other users can share them. Learn about publishing assemblies.

Learn more about assemblies:

• Opening Assemblies

• Getting Assembly Information

• Creating Generic Assemblies

• Updating Assemblies

• Saving Assemblies

• Closing Assemblies

• Publishing Assemblies

Opening Assemblies

To open an existing assembly:

1. In Standard Interface, from the File menu, point to Open and then select Assembly.

2. Press F1 and then follow the instructions in the dialog box help for Open Assembly.

3. Select OK.

Notice that once the subsystem is open, the Edit, Adjust, and Simulate menus become active. We recommend that you familiarize yourself with each menu item.

Getting Assembly InformationYou can get detailed information about assemblies in the current session.

To get information about an assembly:

1. In the Standard Interface, from the File menu, point to Info, and then select Assembly.

2. Press F1 and then follow the instructions in the dialog box help for Assembly Info.

3. Select OK.

Adams/CarAssemblies

56

Creating Generic AssembliesYou can create a generic assembly from specified subsystems.

To create a generic assembly:

1. From the Tools menu, point to Dialog Box, point to Display, and then select dbox_fil_ass_new_gen.

2. Press F1 and then follow the instructions in the dialog box help for New Generic Assembly.

3. Select OK.

Updating AssembliesYou can re-read an assembly file, in case you modified the file by an alternative process. For example, if you edit in a text editor an assembly file stored in the shared database, you can reflect this change in your template-based product by using the update assembly functionality.

To update an assembly:

1. In the Standard Interface, from the File menu, point to Manage Assemblies, and then select Update.

2. Press F1 and then follow the instructions in the dialog box help for Update Assembly.

3. Select OK.

Saving AssembliesYou save assemblies in ASCII or binary format:

• ASCII Assemblies - An ASCII assembly file references subsystems, but does not contain subsystem data. If you want your assembly to be updated with the current template/subsystem files, you should save your assemblies in ASCII format. When you open an ASCII-format assembly, your template-based product opens each individual subsystem, which in turn accesses the current version of each corresponding template.

• Binary Assemblies - A binary assembly is a static snapshot of what's currently in your session. That is, when you reopen a binary assembly, you will return to the exact state at which you left. Adams/Car ignores any subsequent modifications made to templates and/or subsystems, which were originally used to create the assembly, when you open the binary assembly. Therefore, if you want your assembly to be updated with the current template/subsystem files, you should save your assemblies in ASCII format.

Binary assemblies can be very useful, however, if you are working on a project where the templates will not change, and a static snapshot of the assembly is sufficient.

Note that saving an assembly as a binary will not save the plots, nor the setting for simulation (hold_solver_license). It will, however, save the analyses associated with the assembly, and you could re-create plots using a plot configuration file. Learn about plot configuration files.

57Building ModelsAssemblies

To save an assembly:

1. From the File menu, select Save or Save As.

2. If you selected:

• Save - Your template-based product saves the ASCII version of the assembly to the default writable database. Your template-based product prompts you if it detects subsystem changes. It also prompts you if the assembly already exists in the database. For save options, select Save As.

• Save As - Press F1 and then follow the instructions in the dialog box help for Save Assembly. Select OK.

Closing Assemblies

To close an assembly:

1. In the Standard Interface, from the File menu, point to Close, and then select Assembly.

2. Press F1 and then follow the instructions in the dialog box help for Close Assembly.

3. Select OK.

Publishing AssembliesWhen you publish an assembly, you copy each subsystem file included in the assembly definition, including the associated property files for each subsystem, to the target database, which is the database where your template-based product saves all files. You can also select to publish each subsystem's template file. As you publish the assembly, you can select to write over existing files or create backups of the files.

You can also select to update the in-session assembly data to point to the target database or to have the assembly retain the existing references.

The assembly you are publishing must be currently opened in the standard interface, and the target database must be writable. Learn about setting the writable database.

You can choose to publish only a subsystem, not an entire assembly. Learn about publishing a subsystem.

To publish an assembly:

1. From the Tools menu, point to Database Management, and then select Publish Assembly.

2. Press F1 and then follow the instructions in the dialog box help for Publish an Open Assembly.

3. Select OK.

Adams/CarProperty Files

58

Property FilesProperty files are ASCII-based files that contain data for modeling components, such as valve spring, cams, and bushings. Because property files are flat text files, you can use any text editor to create or modify them.

You use property files to:

• Apply the same characteristics or parameters to many components within a template or subsystem. In Adams/Car for example, a suspension might contain many bushings with the same properties. In this case, all the bushings could reference the same property file.

• Share a component between different templates and subsystems.

You can reference property files in different subsystems and templates, as shown in the Example Model Architecture.

All property file types are specified in the configuration file (acar.cfg). When you edit property files, you can save them either with the existing file name or with a new file name. Learn about managing property files through configuration files.

Property files are grouped in classes and stored in databases. Every class (such as bushings and dampers) is filed in the corresponding Database table (in this case, bushings.tbl and dampers.tbl).

A subset of property files define force-displacement or force-velocity characteristics for springs, dampers, bumpstops, reboundstops, and bushings. For those components, you use the Curve Manager or Property File Editor to create, edit, and view property files. You can access the Curve Manager from the Tools menu. From within dialog boxes, you can edit property files using the Curve Manager/Property

File Editor tool and view property files using the View File tool .

Learn about Modifying Component Property File.

59Building ModelsTemplates

TemplatesTemplates are parametric models, built by expert users within the Template Builder. Templates define the default geometric data and topology of models, such as a double-wishbone suspension, an engine cranktrain, or an aircraft landing gear. The components within a template are parametrically defined such that you can use a single template within numerous subsystems.

Templates are intended to be a generic representation of a mechanical system, such that a template that is common to a number of different vehicles can be reused in each of those vehicles. For example, assume that you have two cars, a small car and a large car and that each of the two cars have a double-wishbone front suspension. You could use a double-wishbone template in each of the two vehicles. The only difference is that the large car requires stiffer springs, larger A arms, different dampers, and so on. The basic topology is the same: it is the components/properties that are changed. It is the subsystem file that references the topology of the template but changes the characteristics of the suspension by referencing different springs, parts, dampers, and so on.

Templates provide a quick way to experiment with different subsystems and still retain the basic design components that are required.

A template in its most fundamental form cannot be used in the Standard Interface without first being referenced by a subsystem file. See Generating a Subsystem.

You can modify the data of a template by changing the values of design parameters. Hardpoints, parameter variables, and property files are the design parameters of templates, where:

• Hardpoints define locations for geometry, attachments, and construction frames.

• Parameter variables contain strings, integers, and real values that you can modify in the Standard Interface and store in the subsystem file.

• Property files are referenced by some components.

Templates contain communicators to enable the exchange of information with other templates.

Learn more about templates:

• Opening Templates

• Creating Templates

• Saving Templates

• Closing Templates

• Major Roles

• Location of Templates

Opening Templates When using the Template Builder for the first time, we recommend that you first open some of the example templates we provide and familiarize yourself with them.

Adams/CarTemplates

60

To open an existing template:

1. From the File menu, select Open.

2. Press F1 and then follow the instructions in the dialog box help for Open Template.

3. Select OK.

Creating Templates To ensure that an analysis will work with your new template, when you create a template you must make sure that the template is compatible with other templates and with the test rigs. The template must contain the proper output communicators.

To create a template:

1. From the File menu, select New.

2. Press F1 and then follow the instructions in the dialog box help for New Template.

3. Select OK.

Saving Templates Using the Template Builder, you can save your files in ASCII or Binary File Format. Saving your files in ASCII format provides the benefit of small file sizes and being human readable. On the other hand, saving your files in binary format ensures faster processing, but does not have the benefits associated with ASCII format.

When saving a template that includes a flexible part, your template-based product saves the part as rigid.

To save a template:


2. If you selected:

• Save - Your template-based product saves the binary version of the template to the default writable database and prompts you if the template already exists. For save options, select Save As.

• Save As - Press F1 and then follow the instructions in the dialog box help for Save Template. Select OK.

Note: Notice that once the template is open, the Edit and Build menus become active. We recommend that you familiarize yourself with each menu item.

Note: Notice that once the template is open, the Edit and Build menus become active. We recommend that you familiarize yourself with each menu item.

61Building ModelsTemplates

Closing Templates You can close a template without first saving it to a Database.

To close a template:

1. From the File menu, select Close.

2. Press F1 and then follow the instructions in the dialog box help for Close Template.

3. Select OK.

Major RolesYou assign a major role, or function, to every template. The choices in the Major Role option menu correspond to the available major roles for a template.

A major role is a property of a template. A subsystem inherits the major role of the type on which it is based.

In Adams/Car, examples of major roles are: suspension, steering, and body. Note that for each major role (for example, suspension, steering, and so on) Adams/Car allows only one active subsystem with the minor role any. The choices in the Minor Role option menu correspond to the available minor roles for an Adams/Car subsystem.

Location of TemplatesThe templates are located in the templates.tbl table, or directory, of your template-based product's shared database. The shared database is usually located in your product's installation directory. For location details, see your system administrator.

Adams/CarTest-Rig Templates

62

Test-Rig TemplatesYou can extend the functionality of your templates by converting them into test-rig templates, also referred to as test rigs.

In the template-based products, test rigs are almost completely comparable to regular templates. The basic topological difference between test rigs and regular templates is that besides containing parts that are attached using attachments and forces, test rigs also contain actuator elements, such as motions and forces, to excite the assembly. Just like regular templates, test rigs also contain communicators to enable the exchange of information with other templates.

You use test rigs when creating assemblies. A collection of subsystems and a test rig form an assembly.

Note that the name of a test rig is always preceded by a period and two underscores, that is .__. For example, .__MY_TESTRIG. This is a convention used by all template-based products to differentiate between templates (period and one underscore, ._), subsystems (period, .), and test rigs (period and two underscores, .__).

Learn about test rigs:

• Process Overview

• Creating Test-Rig Templates

• Saving Test-Rig Templates

• Converting Templates into Test Rigs

• Adding Test Rigs to Binaries

Process OverviewThe process of working with test-rig templates involves the following steps:

For Adams/Car:

1. Creating a template and saving it in ASCII format as explained in Creating Test-Rig Templates and Saving Test-Rig Templates.

2. Modifying the ASCII template file to become an ASCII command file, which is now the test rig, as explained in Converting Templates into Test Rigs.

3. Saving the ASCII command file into a binary file as described in Adding Test Rigs to Binaries.

Creating Test-Rig TemplatesYou create test-rig templates the same way you create regular templates.

To create a test-rig template:


2. Press F1 and then follow the instructions in the dialog box for New Template.

63Building ModelsTest-Rig Templates

3. Select OK.

Saving Test-Rig TemplatesYou can save test-rig templates to files, just as you would save regular templates. We recommend that you save test rigs in ASCII format so you can hand edit them. Storing test-rigs in ASCII format also ensures portability from one machine to another. It allows you, for example, to use the same file when building a site binary on either a Windows or UNIX machine.

To save a test-rig template:


2. If you selected:

• Save - Your template-based product saves the binary version of the template to the default writable database and prompts you if the template already exists. For save options, select Save As.

• Save As - Press F1 and then follow the instructions in the dialog box help for Save Template. Select OK.

3. Depending on the template-based product you are using, continue as follows:

• If working in Adams/Car go to Converting Templates into Test Rigs.

Converting Templates into Test RigsTo convert templates into test rigs you must make the following modifications to your ASCII test-rig template file generated from your template-based product:

Removing the Header Information

You must remove the header information that is added at the beginning of the ASCII template file because the command file reader will not understand the information stored in this header and will output errors.

The following example shows a typical header from an ASCII template file:

$-----------------------------------------------MDI_HEADER[MDI_HEADER] FILE_TYPE = 'tpl'

FILE_VERSION = 13.3 FILE_FORMAT = 'ASCII'HEADER_SIZE = 9

(COMMENTS)

Note: You must specifically set the minor roles of communicators in test-rig templates to any. Do not set them to inherit. You set the minor roles to any because generally a template test rig should be capable of connecting with any subsystem.


64

{comment_string}'Simple Double Wishbone Suspension'

$--------------------------------------------TEMPLATE_HEADER[TEMPLATE_HEADER]

MAJOR_ROLE = 'suspension' TIMESTAMP = '1999/07/15,17:21:32' HEADER_SIZE = 5

You should remove all the lines from the beginning of the file up to, and including, the line containing the HEADER_SIZE attribute.

Modifying Adams/View Variables

Templates and test rigs in template-based products have information that is stored in Adams/View variables to determine how the template is used. All templates, including test rigs, have three required variables: major role, minor role, and model class. Test rigs, however, have an additional required Adams/View variable called test rig class.

When you create the test-rig template, your template-based product automatically creates the first three variables. You must, however, manually create the last variable, the test rig class variable.

The following sections introduce the variables:

• Major Role

• Minor Role

• Model Class

• Test-Rig Class

Major Role

The major role of templates and test rigs is stored in an Adams/View variable called role. The major role of a test rig is always analysis.

When creating a test rig, make sure that you set the major role as shown next:

variable create &variable_name = .__acme_4PostRig.role & string_value = "analysis" & comments = "Memory for Adams/Car major role"

Minor Role

The minor role of templates and test rigs is stored in an Adams/View variable called minor_role. The minor role of a test rig is typically any. Setting the minor role to any is very important if you are designing a test rig that is supposed to work with other subsystems that can have different minor roles.

In Adams/Car for example, a suspension test rig should work with either front, rear, or trailer-type suspensions. If the minor role of the test rig were defined as front, the test rig would hook up only to front suspensions.

65Building ModelsTest-Rig Templates

Set the minor role as shown next:

variable create &variable_name = .__acme_4PostRig.minor_role & string_value = "any" & comments = "Memory for Adams/Car minor role"

Model Class

Every assembly in template-based products has a specific model class. The model class of an assembly is stored in an Adams/View variable called model_class. Your template-based product automatically creates this variable when you create the assembly.

Currently, in template-based products, there are four model classes defined: template, subsystem, testrig, and assembly.

Set your model class as shown next:

variable create & variable_name = .__acme_4PostRig.model_class & string_value = "testrig" & comments = "Memory for Adams/Car model class"

Test-Rig Class

You can associate any test rig with a particular class of assembly. In Adams/Car for example, the test rig .__MDI_SUSPENSION_TESTRIG is associated with suspension assemblies. The assembly class of a test rig is stored in an Adams/View variable called testrig_class.

Set the test rig class as shown next:

variable create & variable_name = .__acme_4PostRig.testrig_class & string_value = "full_vehicle" & comments = "Memory for Adams/Car testrig class"

You can reference the variable testrig_class directly from the graphical user interface. In Adams/Car for example, this variable is used in the suspension assembly and the full-vehicle assembly dialog boxes. Each of these two dialog boxes contains an option menu from which you can select the test rig to be included in the new assembly. The option menu will only contain test rigs that are compatible with the particular class of assembly you specified.

The following steps shows how you can reference testrig_class from the Adams/Car interface. You can follow the same basic steps for the other template-based products.

To reference testrig_class from the Adams/Car interface:

1. From the File menu, point to New, and then select Suspension Assembly.

2. Press F1 and then follow the instructions in the dialog box help for New Suspension Assembly.

3. Select OK.


66

Adding Test-Rigs to Binaries in Adams/CarAdding a test rig to your private or site binary makes it available for use whenever you start a private or site session. See Organizing Custom Code.

You should move the test rig you modified from the template table (templates.tbl) in your template-based product databases to a directory that contains the source for the custom private or site binary file. Typically, you will need to create custom analysis macros that work with the new test rig. All these files should be located in the same directory structure.

For example, you could enter this command in the acar_build.cmd file to read the test rig:

file command read & file=(eval(getenv("MDI_ACAR_SITE")//"/analysis/models/acme_4PostRig.cmd"))

When you add this command to the acar_build.cmd file, Adams/Car reads in and stores the test rig in the private or site binary, making the test rig available for use whenever you start an Adams/Car private or site session.

As as additional option, you can rename your test rig file from the .tpl extension to a .cmd extension to reflect the fact the test rig is now a command file.

Learn about Creating and Modifying Macros.

67Building ModelsCommunicators

CommunicatorsCommunicators are the key elements in template-based products that enable the exchange of information between subsystems, templates, and the test rig in your assembly.

An assembly requires two directions of data transfer between its subsystems. To provide for these two directions of data transfer, the template-based products have two types of communicators:

• Input communicators - Request information from other subsystems or test rigs.

• Output communicators - Provide information to other subsystems or test rigs.

In Adams/Car for example, a mount communicator in the rack and pinion steering templates outputs the rack part name so that tie rods of suspension templates can attach to the rack. In addition, a mount communicator in the steering template inputs a part name. The steering template uses the part name to determine where to attach the steering column.

Learn more about communicators:

• Creating/Modifying Input Communicators

• Creating/Modifying Output Communicators

• Communicator Entity Class

• Communicator Roles

• Communicator Naming

• Matching Communicators During Assembly

• Displaying Communicator Information

• Testing Communicators

Creating/Modifying Input CommunicatorsYou can create or modify input communicators as explained next. You must be in template-builder mode to do this.

To create/modify input communicators:

1. From the Build menu, point to Communicator, point to Input, and then select New/Modify.

2. Press F1 and then follow the instructions in the dialog box help for Create/Modify Input Communicator.

3. Select OK.

Creating/Modifying Output CommunicatorsYou can create or modify output communicators as explained next. You must be in template-builder mode to do this.

Adams/CarCommunicators

68

To create/modify output communicators:

1. From the Build menu, point to Communicator, point to Output, and then select New/Modify.

2. Press F1 and then follow the instructions in the dialog box help for Create/Modify Output Communicator.

3. Select OK.

Communicator Entity ClassThe class of a communicator indicates the kind of information it exchanges. For example, communicators of the class marker exchange a location and an orientation through a construction frame name and a part name. The classes of communicators and the information that each class exchanges are listed in table Communicator Entity Class. The classes apply to both input and output communicators.

In Adams/Car, and Adams/Driveline, communicators can be either single or be part of a symmetrical pair, either left or right. The table below provides additional information about entity classes.

The class: Exchanges:

The following entity classes do not have symmetry and, therefore, are always single, by default:

Array Adams/Solver array name.

Differential equation Differential equation name.

Motion Motion name.

Parameter Variables Parameter variable name.

Spline Spline name.

Solver variable Adams/Solver variable name. You must use an Adams/Solver variable, not an Adams/View variable. Unlike an Adams/View variable, an Adams/Solver variable's computation occurs during analysis. Your template-based product generates Adams/Solver variables as state variables.

The following entity classes have symmetry:

Mount Part name to provide connections between subassemblies. As a shortcut, the template-based products also automatically create input mount communicators when you create a mount part.

Marker Creation of a marker output communicator results in the creation of a new marker whose location is defined by a user-input construction frame and which is located on a user-input part. The identity of this marker is passed through this communicator to provide both location and part information. If the construction frame is part of a symmetrical pair, the template-based products create an input communicator for each construction frame in the pair.

Joint Joint name.

Joint-for-motion Joint name.


Communicator Minor RolesEach communicator has a minor role. A minor role defines the communicator's position in the assembly. The template-based products provide you with minor roles, as shown in the following table:

You can define a communicator's minor role when you create it. For example, if you want to provide input to or output from subsystems of specific roles, then you set the minor role for communicators when you create them. We recommend, however, that you do not set a communicator's minor role. Instead, let the subsystem determine the minor role by setting it to inherit, in which case the communicator inherits the minor role from the subsystem in which it is embedded. For example, in Adams/Car a suspension template might be used to define either a front or rear suspension subsystem. By letting the subsystem determine the minor role, the assembly process attaches a steering system to the front suspension and not to the rear.

Communicator NamingAfter you create a communicator, your template-based product assigns a prefix to the name. For example, it creates a prefix, cil_ where:

• ci indicates it is an input communicator. If it were an output communicator, the template-based product would use co.

Bushing Bushing name.

Location The location of the named hardpoint or construction frame. If the hardpoint is part of a symmetrical pair, the template-based products create two input communicators, one for each hardpoint in the pair.

Part Part name.

Orientation The orientation of the named construction frame.

Real parameter A parameter variable name of the type real.

Integer parameter A parameter variable name of the type integer.

This template-based product: Has these communicator minor roles:

Adams/Car • any (see Communicator Minor Role: Any )

• inherit (see Communicator Minor Role: Inherit )

• front (see Communicator Minor Role: Front, Rear, Middle)

• rear (see Communicator Minor Role: Front, Rear, Middle)

• trailer

The class: Exchanges:


70

• l indicates it is for the left side of a symmetrical pair. If it were for the right side, the template-based product would use an r. If it were a single communicator, it would have an s (cis).

If you create a mount part, your template-based product automatically creates an input communicator of the class mount. It uses the name of the mount part as the name of the communicator and appends the prefix ci[lrs]_ to it, depending on whether or not it is a left, right, or single communicator. For example, if you create a mount part of mtl_rack_mount, your template-based product creates an input communicator with the name cil_rack_mount, where the l indicates it is for the left side.

As you name communicators, you should ensure that any input and output communicators that exchange information have identical matching names. In Adams/Car for example, the name you give to communicators that exchange a part name during assembly might be ci_strut_mount and co_strut_mount, each of which has a matching name of strut_mount. In addition, if you are working with MSC.Software templates, you must ensure that you use the same naming conventions as the MSC.Software templates. Learn about matching communicators.

Matching Communicators During AssemblyFor a pair of communicators to exchange information during assembly, the communicators must:

• Have identical matching names.

• Be of opposite types (one input, one output).

• Be of the same symmetry type (left, right, or single).

• Be of the same class (exchange the same type of information).

• Have the same minor role or be assigned a role of any.

If all pieces of information match, your template-based product determines an input/output communicator pair.

If an input communicator does not have a corresponding output communicator, your template-based product returns a warning message, and, if the input communicator belongs to the class mount, the template-based product assigns the mount part to ground. You can still analyze the model even if it does not have matching communicators. In fact, you may find this helpful if you want to run an analysis of a subsystem without attaching another subsystem to it.

In Adams/Car for example, the following pairs of input and output communicators match and exchange a part name during assembly.

Sample of Matching Input and Output Communicators

The pair: Belongs to the class: From minor role: To minor role:

cil_strut_mount mount front

col_strut_mount mount front

cil_strut_mount mount any


You can match an input communicator with only one output communicator. You can, however, match an output communicator with any number of input communicators.

You should always check the warning messages during the assembly, especially if the warning refers to an input communicator of class mount that does not get assigned and is, therefore, attached to ground.

Displaying Communicator InformationYou can display information about communicators in each template or test rig. The communicator information includes the names of the communicators, their classes, and minor roles. You can choose to display all types and classes of communicators in the templates and test rigs or display only a specified set of types and classes.

To display information about communicators:

1. From the Build menu, point to Communicator, and then select Info.

2. Press F1 and then follow the instructions in the dialog box help for Communicators Info.

3. Select OK.

Information window appears. It displays the communicator information for each template or test rig, grouped by each class of communicator that you selected.

Testing CommunicatorsYou can perform a test to verify that you have correctly specified input and output communicators in your template. You can use this test to determine whether or not you need to add or modify communicators to correctly create an assembly.

When you perform the test, you specify the model names of one or more existing templates or test rigs. Although you can specify a single template, you should specify all the templates containing communicators that transfer information between the selected template. You must specify a minor role for each template, subsystem, or test rig you chose to test.

After you perform the test, your template-based product lists the matching input and output communicators, the unmatched input communicators, and the unmatched output communicators for the templates, subsystems, and test rigs you selected. You can save the test information to a file.

To test communicators:

1. From the Build menu, point to Communicator, and then select Test.

col_strut_mount mount front

cil_strut_mount mount front

col_strut_mount mount any

The pair: Belongs to the class: From minor role: To minor role:


72

2. Press F1 and then follow the instructions in the dialog box help for Test Communicators.

3. Select OK.

The Information window appears. It contains a list of the communicators that match other communicators and a list of those that do not. It shows the matched communicators followed by the unmatched communicators. The lists include the names of the input and output communicators and the names of the templates to which they belong. Often, you'll see many communicators that are unmatched. Many of these communicators are related to subsystems or test rigs that you do not currently have open.

If you want to fully test the communicators in your template, you should open the other templates with which you want the template to communicate. In Adams/Car for example, if you are creating a suspenion template, the template must be able to communicate with a steering template and the suspension test rig.

Working with Components

Adams/CarIntroducing the Components

74

Introducing the Components The template-based products offer a number of component definitions that allow you to quickly and efficiently create components such as springs, dampers, and tires in the Template Builder. This allows the expert user to generate complex components without being overly concerned with the underlying elements, such as parts, markers, and geometry.

Components provide the building blocks required to define topological systems. Components are designed to be intuitive, to allow you to create templates quickly and easily.

The expert user can create, modify, and delete components using the Template Builder. In the Standard Interface, either the standard or the expert user can only modify components. Learn about user access.

The components within a template are parametrically defined such that you can use a single template to represent numerous subsystems.

General Information About Components• Creating Components

• Modifying Components

• Deleting Components

• About the Naming Convention

Information About a Particular Component• Hardpoints

• Construction Frames

• Parts

• Markers

• Geometry

• Attachments

• Forces

• Wheels, Adjustable forces and Gears

• Actuators

• Condition Sensors

• Feedback Channels

• Data Elements, Requests and Variables

75Working with ComponentsIntroducing the Components

Creating Components You can create components only in the Template Builder. The Template Builder design leads you through a step-by-step process for creating components: the Build menu is organized such that you can start at the top of the menu, building basic components, and work your way down, attaching these basic components together and building increasingly complex components.

For information about a certain component, see the topic for that component.

The following example shows how you can create arm geometry. You follow the same basic steps to create any other component listed under the Build menu.

To create arm geometry:

1. From the Build menu, point to Geometry, point to Arm, and then select New.

2. Press F1 and then follow the instructions in the dialog box help for Create/Modify Arm Geometry.

3. Select one of the following:

• OK if you want to execute the command and close the dialog box.

• Apply if you want to execute the command but keep the dialog box open so you can continue to work in it.

• Cancel if you decide not to execute the command and close the dialog box.

Modifying Components Depending on the component you want to modify, one or more of the following methods will be available:

• Modifying Component Parameters

• Modifying Component Property File

• Replacing Instance Definition

Modifying Component Parameters

You can modify component parameters in either interface, as follows:

• In the Template Builder - After you create components in the Template Builder, you can modify any of their parameters, as needed.

• In the Standard Interface - The standard user can reference an existing template by either opening or creating a subsystem file. The standard user can modify only selected parameters in the Standard Interface.

The following examples show how you can modify component parameters in either interface. You use the same basic steps to modify any component’s parameters.


76

In Standard Interface, to modify arm geometry:

1. Right-click an arm geometry, and then select Modify.

2. Press F1 and then follow the instructions in the dialog box help for Modify Arm.

3. Select OK.

In Template Builder, to modify arm geometry:

1. From the Build menu, point to Geometry, point to Arm, and then select New/Modify.


3. Select OK.

Modifying Component Property File

You can modify property files using either of the following:

• Any text editor - When working in any of the template-based products, you can open a text editor, such as vi on UNIX and Notepad on NT, display the property file referenced by the component you want to change, modify any of the parameters as needed, and then save your changes.

• The Curve Manager - You can modify some property files as explained in Modifying Property Files Using the Curve Manager.

Modifying Property Files Using a Text Editor

If you want to modify a property file using a text editor, you can find the location of the particular database that a property file uses by following the steps outlined next.

To find the location of a database:

• From the Tools menu, point to Database Management, and then select Database Info. The Information window appears, displaying the path of the database.

Modifying Property Files Using the Curve Manager

You can use the Curve Manager to modify a select set of property files.

To modify Adams/Car property files:

1. From the screen, right-click the component you want to modify, for example a spring, point to the component name, and then select Modify.

The Modify Spring dialog box appears.

2. Select the Curve Manager tool .

The Curve Manager appears.

Note: You can only change a limited number of parameters in the Standard Interface.


3. Change any parameters as needed.

Replacing Instance Definition

Another way of modifying components is to change the definition of the component you are using with another definition of the same component. For example, you can replace a coil spring with an air spring. The following example shows how you can change a component's definition. You follow the same basic steps to change the definition of other components.

Components currently supported include: air spring, bushing, damper, and spring, as well as application-specific components.

To change component definition:

1. In Standard Interface, right-click a component, point to its name, and then select Replace Instance.

2. Press F1 and then follow the instructions in the dialog box help for Replace Instance Definition.

3. Select OK.

Deleting Components You can delete components only in the Template Builder. If you try to delete a component that is dependent on other components, your template-based product informs you that the component is dependent on others, and if you delete it, the dependents also are deleted.

Because not all the components you can create and delete in the Template Builder have a graphical representation, you cannot delete some components by right-clicking on them. The following procedures explain how you can delete both types of components: those that have a graphical representation as well as those that don’t.

To delete components that do not have graphical representation:

1. From the Build menu, point to the component you want to delete, and then select Delete.

The appropriate Delete dialog box appears.

2. Fill in the dialog box as appropriate, and then select either of the following:

• OK if you want to execute the command and close the dialog box.

• Apply if you want to execute the command but keep the dialog box open so you can continue to work in it.

Your template-based product does one of the following:

• Deletes the component.

Note: In Adams/Car you can change the component definition only in the Standard Interface.


78

• Checks if the component has dependencies, and if the component does have dependencies, it informs you and gives you three options:

• Proceed with the delete command

• Highlight and list the dependents

• Cancel the delete command

To delete components that have graphical representation:

• Do one of the following:

• Right-click the component you want to delete from the screen, point to the component name, and then select Delete.

• Complete steps 1 and 2, above.

Your template-based product does one of the following:

• Deletes the component.

• Checks if the component has dependencies, and if the component does have dependencies, it informs you and gives you three options:

• Proceed with the delete command

• Highlight and list the dependents

• Cancel the delete command

About the Naming ConventionThe template-based products use a naming convention to allow you to easily determine a component’s type from it name. When you create a new component in the Template Builder, your template-based product automatically adds a prefix based on the component type and symmetry. The first two letters of the prefix indicate the component type. The third letter indicates the symmetric information of the entity. This letter can be l, r, or s, indicating left, right, or single, respectively.

The exception to this rule is the prefix for geometry entities, where the first three letters are always gra. The next three letters describe the type of geometry. These letters can be arm, cyl, ell, lin, and out, corresponding to the following types of geometry: arm, cylinder, ellipse, link, and outline.

The following table lists the prefixes associated with the Template Builder entities. The list is sorted alphabetically by prefix.

Prefix: Entity type:

bg[lrs]_ Bushing (always active)

bk[lrs]_ Bushing (kinematically inactive)

bu[lrs]_ Bumpstop (Adams/Car only)

cf[lrs]_ Construction frame


ci[lrs]_ Input communicator

co[lrs]_ Output communicator

css_ Condition sensor

da[lrs]_ Damper (Adams/Car only)

fb[lrs]_ Flexible body

ff[lrs]_ User-function feedback channel

ge[lrs]_ General part

gk[lrs]dif_ Gear differential (kinematically active)

gk[lrs]red_ Gear reduction (kinematically active)

gp[lrs]_ General parameter

gr[lrs]dif_ Gear differential (always active)

gr[lrs]red_ Gear reduction (always active)

graarm Arm geometry

gracyl_ Cylinder geometry

graell_ Ellipse geometry

gralin_ Link geometry

graout_ Outline geometry

gs[lrs]_ General spline

gv[lrs]_ General variable

hp[lrs]_ Hardpoint

ip[lrs]_ Interface part

jf[lrs]_ Joint force actuator

jk[lrs]_ Joint (kinematically active)

jm[lrs]_ Joint motion actuator

jo[lrs]_ Joint (always active)

mt[lrs]_ Mount part

nr[lrs]_ Nonlinear rod

ns[lrs]_ Spring

ph[lrs]_ Hidden parameter variable

pt[lrs]_ Point torque actuator

pv[lrs]_ Parameter variable

re[lrs]_ Reboundstop (Adams/Car only)

sw[lrs]_ Switch part



80

ti[lrs]_ Tire force (Adams/Car only)

ue[lrs]_ User-defined entity

wh[lrs]_ Wheel part (Adams/Car only)


81Working with ComponentsHardpoints

HardpointsHardpoints contain location information and are the basic building blocks for most other components. Hardpoints have no orientation. If you need components that hold both location and orientation information, use construction frames.

Hardpoints and construction frames are also referred to as coordinate references.

You use the Template Builder’s Build menu to create, modify, and delete hardpoints. When you create hardpoints, you can define them symmetrically or as a single point in space. When defining hardpoints symmetrically, you could, for example, define a left hardpoint and the right hardpoint is automatically generated as a parametric point.

Creating a Hardpoint

To create a hardpoint:

1. From the Build menu, point to Hardpoint, and then select New.

2. Press F1 and then follow the instructions in the dialog box help for Create Hardpoint.

3. Select OK.

Modifying a Hardpoint

In Standard Interface, to modify a hardpoint:

1. From the Adjust menu, point to Hardpoint, and then select Modify.

2. Press F1 and then follow the instructions in the dialog box help for Modify Hardpoint Location.

3. Select OK.

In Template Builder, to modify a hardpoint:

1. From the Build menu, point to Hardpoint, and then select Modify.

2. Press F1 and then follow the instructions in the dialog box help for Modify Hardpoint Location.

3. Select OK.

Modifying Several Hardpoints at a Time

If you want to modify several existing hardpoints at a time, you can use a table editor to do so.

In Standard Interface, to modify several hardpoints at a time:

1. From the Adjust menu, point to Hardpoint, and then select Table.

2. Press F1 and then follow the instructions in the dialog box help for Hardpoint Modification Table.

3. Select Apply.

Adams/CarHardpoints

82

In Template Builder, to modify several hardpoints at a time:

1. From the Build menu, point to Hardpoint, and then select Table.

2. Press F1 and then follow the instructions in the dialog box help for Hardpoint Modification Table.

3. Select Apply.

83Working with ComponentsConstruction Frames

Construction FramesConstruction frames contain both location and orientation information, and are the basic building blocks for many other components. When you need only location and no orientation information, hardpoints are the correct components to use.

Hardpoints and construction frames are also referred to as coordinate references.

You can define construction frames symmetrically. To easily locate and orient construction frames without having to worry about complex rotations and translations, you can use various options:

• Summary of Location Dependency Options

• Summary of Orientation Dependency Options

To create or modify a construction frame:

1. From the Build menu, point to Construction Frame, and then select New/Modify.

2. Press F1 and then follow the instructions in the dialog box help for Create/Modify Construction Frames.

3. Select OK.

Adams/CarParts

84

PartsYou can build the following types of parts in Template Builder:

• General Parts

• Interface Parts

• Flexible Bodies

• Nonlinear Beams

• Mount Parts

• Switch Parts

General PartsA general part is a rigid part that is defined by its location, orientation, mass, inertia, and center of gravity.

Note that the computed mass properties are not parametric. Your template-based product does not update the mass properties when the geometry changes, if hardpoints have changed position, for example. If you want to have the part mass re-computed based upon a part’s geometry, you must explicitly have your template-based product compute the mass properties based on the changed geometry by calculating the mass for the general part, using the Build or Adjust menus. Alternatively, you can change the mass properties to user-defined values by modifying the general part using the Build or Adjust menus.

In the Standard Interface, general parts are enhanced to be either rigid or flexible. Learn about flexible parts.

Creating or Modifying a General Part

In Standard Interface, to create or modify a general part:

1. From the Adjust menu, point to General Part, and then select Modify.

2. Press F1 and then follow the instructions in the dialog box help for Modify General Part.

3. Select OK.

In Template Builder, to create or modify a general part:

1. From the Build menu, point to Parts, point to General Part, and then select New/Modify.

2. Press F1 and then follow the instructions in the dialog box help for Create/Modify General Part.

3. Select OK.

Calculating the Mass of a General Part

You can calculate the mass based on material properties (steel, aluminum, and so on) or enter a material density. The mass will be based on the volume of the associated geometry.

85Working with ComponentsParts

To calculate the mass of a general part:


• From the Build menu, point to Parts, point to General Part, and then select Modify.

• From create/modify dialog boxes, select .

Using the General Part Wizard

You can use the general part wizard to create simple geometry. Using the general part wizard allows the Template Builder to automatically calculate mass and inertia properties. You can create either a link or an arm and choose the material properties.

To use the general part wizard:

1. From the Build menu, point to Parts, point to General Part, and then select Wizard.

2. Press F1 and then follow the instructions in the dialog box help for General Part Wizard.

3. Select OK.

Interface PartsInterface parts let you connect flexible bodies to the rest of your template. You cannot use joints or bushings to connect general parts and flexible bodies: you must use interface parts.

To create or modify interface parts:

1. From the Build menu, point to Parts, point to Flexible Body, point to Interface Part, and then select New/Modify.

2. Press F1 and then follow the instructions in the dialog box help for Create/Modify Interface Part.

3. Select OK.

Flexible BodiesTemplate-based products use descriptions of flexible bodies, named modal neutral files (MNF), from a finite element (FEM) program. The MNF is a binary, platform-independent file that combines compact storage and efficiency of data access.

The information in an MNF includes:

• Geometry (locations of nodes and node connectivity)

• Nodal mass and inertia

• Mode shapes

• Generalized mass and stiffness for mode shapes

The Template Builder uses a method of modeling flexible bodies named modal flexibility. Modal flexibility assigns a set of mode shapes (eigenvectors) to a flexible body. The principle of linear

Adams/CarParts

86

superposition is then used to combine the mode shapes at each time step to reproduce the total deformation of the flexible body. This method can be very useful in problems that are characterized by high elasticity and moderate deflections.

In Standard Interface, to modify a flexible body:

1. If the displayed subsystem or assembly has a flexible part, from the Adjust menu, point to Flexible Body, and then select Modify.

2. Press F1 and then follow the instructions in the dialog box help for Modify Flexible Body.

3. Select OK.

In Template Builder, to create or modify a flexible body:

1. From the Build menu, point to Parts, point to Flexible Body, and then select New/Modify.

2. Press F1 and then follow the instructions in the dialog box help for Create/Modify Flexible Body.

3. Select OK.

Nonlinear BeamsA nonlinear beam consists of one cylindrical/rectangular segment or several segments connected to each other at Coordinate References. The cylindrical elements can have hollow cross sections to represent pipes. The segments form a shaft with a stiffness appropriate to the cross-sectional area and material stiffness.

Using a nonlinear beam offers you a quick and easy way to deliver flexibility during early design stages.

The mass and inertia properties of a nonlinear beam are determined according to the outer radius, inner radius, and material type, with the cylinder wall thickness = (outer radius - inner radius).

Nonlinear beams can be:

• Rigid - A rigid nonlinear beam is a sequence of cylinders that belongs to one part. You can use rigid nonlinear beams to model links that do not have a simple straight-line shape.

• Flexible - For a flexible nonlinear beam, your template-based product creates a separate part for each hardpoint you specify. Your template-based product cuts into two pieces the cylinder between two hardpoints, with each belonging to one of the two parts associated with the hardpoints. The two halves are then connected elastically by a beam element. You can use flexible nonlinear beam to model components such as anti-roll bars.

To create or modify a nonlinear beam:

1. From the Build menu, point to Parts, point to Nonlinear Beam, and then select New/Modify.

2. Press F1 and then follow the instructions in the dialog box help for Create/Modify Nonlinear Beam.

3. Select OK.

87Working with ComponentsParts

Mount PartsA mount part is a massless part that acts as an alias for another part in a separate template. You can use this alias part as you would use the real part when creating joints, springs, contacts, and so on. A mount part is fixed to ground by default. If there are matching communicators of type mount found during the assembly process, the template-based product fixes the mount part to the part specified as the value of the corresponding output communicator.

To create or modify a mount part:

1. From the Build menu, point to Parts, point to Mount, and then select New/Modify.

2. Press F1 and then follow the instructions in the dialog box help for Create/Modify Mount Part.

3. Select OK.

Switch PartsA switch part is a massless part that enables flexible topology. You can use this switch part as you would use any real part when creating joints, springs, bushings, and so on. Your template-based product has a list of real parts related to each switch part. At any time, the switch part is fixed to one and only one of the parts on the part list.

A switch part lets you explore two different topological solutions. For example, a suspension may connect either directly to a chassis or to a subframe, depending on the subsystems active during assembly. The switch part makes these topological solutions possible. Following assembly, switch parts are automatically deleted.

When you choose a new part in the Switch to Part pull-down menu, the switch part changes the part it is fixed to, and all the joints and forces acting on the switch part will act on the new part. The switch part concept allows you to model and investigate different topologies.

See Switch Part Example for Adams/Car.

Creating or Modifying Switch Parts

In Standard Interface, to modify a switch part:

1. From the Adjust menu, select Switch Part.

2. Press F1 and then follow the instructions in the dialog box help for Modify Switch Part.

3. Select OK.

In Template Builder, to create or modify a switch part:

1. From the Build menu, point to Parts, point to Switch, and then select New/Modify.

2. Press F1 and then follow the instructions in the dialog box help for Create/Modify Switch Part.

3. Select OK.

Adams/CarParts

88

Removing Switch Parts

To remove a switch part:

1. From the Tools menu, select Remove Switch Part.

2. Press F1 and then follow the instructions in the dialog box help for Switch & Remove Switch Parts.

3. Select OK.

89Working with ComponentsMarkers

MarkersA marker defines a local coordinate system on any part in your model or on ground. A marker has a location (the origin of the coordinate system) and an orientation.

To create or modify a marker:

1. From the Build menu, point to Marker, and then select New/Modify.

2. Press F1 and then follow the instructions in the dialog box help for Create/Modify Marker.

3. Select OK.

Adams/CarGeometry

90

GeometryGeometry components in the template-based products allow you to easily build parametric representations of standard parts. If mass and inertia information is unavailable, you can automatically calculate the mass of the general part based on the size of the geometry.

You can build the following geometry components:

• Arm Geometry

• Link and Cylinder Geometry

• Ellipsoid Geometry

• Outline Geometry

Note that the computed mass properties, based on geometry, are not parametric. Your template-based product does not update the mass properties when the geometry changes, if hardpoints have changed position, for example. If you want to have the part mass re-computed, based upon a part’s geometry, you must explicitly have your template-based product compute the mass properties based on the changed geometry, by Calculating Mass for the General Part, using the Build or Adjust menus. Alternatively, you can change the mass properties to user-defined values by modifying the General Part, using the Build or Adjust menus.

Arm GeometryAn arm part is a solid triangular plate defined by three Coordinate References and a thickness. If necessary, you can automatically update the mass and inertia properties of the general part.

In Adams/Car, you could use the arm geometry to view the control arm of a MacPherson suspension.

In Standard Interface, to modify arm geometry:

1. Right-click an arm geometry, and then select Modify.

2. Press F1 and then follow the instructions in the dialog box help for Modify Arm.

3. Select OK.

In Template Builder, to create or modify arm geometry:

1. From the Build menu, point to Geometry, point to Arm, and then select New/Modify.


3. Select OK.

Link and Cylinder GeometryThe link and cylinder geometry are very similar. The only differences exist in the method used to define the geometry:

91Working with ComponentsGeometry

• The link geometry consists of a cylinder whose ends you define using two hardpoint locations and a radius. You can use links to view the tie rods of certain suspensions.

• You define the cylinder using a construction frame, rather than two hardpoints. The centerline of the cylinder follows the z-axis of the construction frame. You can define the cylinder so that it has length in both the positive and negative z-axis. You can use cylinders to view the strut rods of certain suspensions.

If necessary, you can automatically update the mass and inertia properties of the general part.

Creating or Modifying Link Geometry

In Standard Interface, to modify link geometry:

1. Right-click a link, and then select Modify.

2. Press F1 and then follow the instructions in the dialog box help for Modify Link.

3. Select OK.

In Template Builder, to create or modify link geometry:

1. From the Build menu, point to Geometry, point to Link, and then select New/Modify.

2. Press F1 and then follow the instructions in the dialog box help for Create/Modify Link Geometry.

3. Select OK.

Creating or Modifying Cylinder Geometry

To create or modify link geometry:

1. From the Build menu, point to Geometry, point to Cylinder, and then select New/Modify.

2. Press F1 and then follow the instructions in the dialog box help for Create/Modify Cylinder Geometry.

3. Select OK.

Ellipsoid GeometryAn ellipsoid geometry is defined by a Coordinate Reference and a user-specification of x, y, and z dimensions. You can use ellipsoids to represent spherical elements of your template. A sphere is an ellipsoid whose x, y, and z radii have the same values.

You can use two different methods of defining an ellipsoid:

• Use a link to define the radius and then specify a scaling factor in each of the orthogonal axes

• Define a measurement in each axis

If necessary, you can automatically update the mass and inertia properties of the general part.

Adams/CarGeometry

92

To create or modify ellipsoid geometry:

1. From the Build menu, point to Geometry, point to Ellipsoid, and then select New/Modify.

2. Press F1 and then follow the instructions in the dialog box help for Create/Modify Ellipsoid Geometry.

3. Select OK.

Outline GeometryYou can use the outline to draw a line between different hardpoint locations. You can choose to define either an open or a closed outline. In general, you would use outlines to visualize the general form of parts. For example, you would add outline geometry to represent the subframe of a vehicle.

Because the geometry entity has no thickness, you cannot update the mass and inertia properties of an outline.

To create or modify outline geometry:

1. From the Build menu, point to Geometry, point to Outline, and then select New/Modify.

2. Press F1 and then follow the instructions in the dialog box help for Create/Modify Outline Geometry.

3. Select OK.

93Working with ComponentsAttachments

AttachmentsWhen working with template-based products, you can use two types of attachments:

• Joints

• Bushings

JointsJoints define a rigid connection between two parts and help define the motion of the parts. The following table lists the joints the template-based products support, along with information about their degrees of freedom (DOF):

Joint name: Number of DOF: Type of motion DOFs allow:

Translational 1 Translation of one part with respect to another while all axes are co-directed.

Revolute 1 Rotation of one part with respect to another along a common axis.

Cylindrical 2 Translation and rotation of one part with respect to another.

Spherical 3 Three rotations of one part with respect to the other while keeping two points, one on each part, coincident.

Planar 3 The x-y plane of one part slides with respect to another.

Fixed 0 No motion of any part with respect to another.

Inline 4 One translational and three rotational motions of one part with respect to another.

Inplane 5 Two translational and three rotational motions of one part with respect to another.

Orientation 3 Constrains the orientation of one part with respect to the orientation of another one, leaving the translational degrees of freedom free.

Parallel_axes 4 Three translational and one rotational motions of one part with respect to another.

Perpendicular 5 Three translational and two rotational motions of one part with respect to another.

Convel 2 Two rotations of one part with respect to the other while remaining coincident and maintaining a constant velocity through the spin axes.

Hooke 2 Two rotations of one part with respect to the other while remaining coincident.

Adams/CarAttachments

94

You can use different parametric orientation options to define the location and direction of the joint.

To create or modify a joint:

1. From the Build menu, point to Attachments, point to Joint, and then select New/Modify.

2. Press F1 and then follow the instructions in the dialog box help for Create/Modify Joint Attachment.

3. Select OK.

Working with BushingsBushings provide a six degree-of-freedom force relationship for connecting two components. The force is applied between a marker on each component. The force depends on the relative displacement, and (in the case of hysteretic bushings), the relative velocity of the two markers.

The forces generated due to translational and rotational motion are entirely uncoupled from each other. In the description of the bushing formulation that follows, you can apply the force dependencies, described next, to either translational or rotational behavior. Therefore, a statement such as fi = h (relative

displacements, relative velocities) implies the following:

• Forces: fi = g (translational displacements, translational velocities)

• Moments: fi = h (angular displacements, angular velocities)

Learn about bushings:

• Creating and Modifying Bushings

• Stiffness Forces Computation

• Damping Forces Computation

• Bushing Specifications in the Adams Dataset (.adm)

Creating and Modifying Bushings

When working in Template Builder, you can create bushings and then modify them. When working in Standard Interface, you can only modify bushings. Learn about the Interface Modes.

Nonlinear Bushings

To create a nonlinear bushing:

1. From the Build menu, point to Attachments, point to Bushing, and then select New.

2. Press F1 and then follow the instructions in the dialog box help for Create/Modify Bushing Attachment.

3. Select OK.


To modify a nonlinear bushing in the Template Builder:

1. To display the modify dialog box, do one of the following:

• From the Build menu, point to Attachments, point to Bushing, and then select Modify. To load the parameters for a specific bushing, you must specify the bushing you want to modify.

• Right-click a bushing, point to its name, and then select Modify. The dialog box has the bushing parameters already loaded.

2. Press F1 and then follow the instructions in the dialog box help for Create/Modify Bushing Attachment.

3. Select OK.

To modify a nonlinear bushing in the Standard Interface:

1. In Standard Interface, right-click a bushing, point to its name, and then select Modify. The dialog box has the bushing parameters already loaded.

2. Press F1 and then follow the instructions in the dialog box help for Modify Bushing.

3. Select OK.

Linear Bushings

To modify a linear bushing in the Standard Interface:

1. Right-click a bushing, point to its name, and then select Modify. The dialog box has the bushing parameters already loaded.

2. Press F1 and then follow the instructions in the dialog box help for Modify Linear Bushing.

3. Select OK.

Stiffness Forces Computation

In the expressions that follow:

• i, j k, l are indices whose integer values of 1 to 3 indicate application to the x, y, and z coordinate directions, respectively

• All uppercase letters represent constants

The Transformed Displacement, q

Adams/Solver computes the stiffness forces based on a bushing displacement vector, q, which is determined by transformation to account for any inter-axial coupling. Therefore:

For uncoupled directions , q is given by:

For coupled directions , q is given by:

k D

qk rk=

k D


96

with

and

where the Adams internal variables are:

and the user-specified constants are:

This formulation allows the elements of the displacement vector, x, to be scaled up by a user-specified factor, H, and/or offset by a user-specified displacement offset, Qk, to determine the transformed

displacement vector, qk, which becomes the lookup point in the selected stiffness force characteristic (see

next).

The Stiffness Force, f

For uncoupled directions , the resulting force, f, is given by:

For coupled directions , f, is given by:

with .

xk - Displacement of the modeled bushing in the k direction

rk - Displacement of the physical bushing in the k direction

qk - Ordinate (lookup point) in the stiffness force characteristic

D - Scalar magnitude of the bushing displacement vector

Hk - Horizontal (displacement) scaling for the kth direction (disp_scale); can be used to perform unit conversions

Qk - Displacement offset for the kth direction (disp_offset);can be used to specify an offset between the modeled bushing and the physical bushing (perhaps caused by the rotational preload introduced by the assembly process)

qk m rk sgn=

m rl2

l 1=

D

=

rk Hk xk Qk–=

k D

fk Gk Vk yk qk'vk –=

k D

fk Gk Vk wk yk qk'vk –=

wk

rk

m-------=


Where the Adams internal variables are:


See the following sections for the precise mathematical descriptions of the two alternative coupling formulations.

Note about the scaling factors, V and H:

Expressing the Stiffness Force Characteristic

You can use a number of formulations to express the stiffness force characteristic of the bushing, by appropriately setting the integer value of stiffness_type (see above), and providing the necessary data in the .adm file.

Learn how the Stiffness Force Characteristics are expressed in the .adm file.

Linear

The linear characteristic is straightforward, and is defined using a stiffness, k:

Piecewise Linear

The piecewise linear characteristic is defined as:

fk - Stiffness component of the force in the kth direction, determined by accounting for preload, scaling factors, and inter-axial coupling

yk - Force returned internally by the user-defined (positive-positive) bushing stiffness characteristic for the kthdirection

wk - Weighting of the returned force for the kth direction (0 to 1, for coupled directions only)

Gk - Force offset (preload) for the kth direction (force_offset)

Vk - Vertical (force) scaling for the kth direction (stiffness_force_scale)

Note: Regardless of the bushing formulation, a doubling of the scale factor, V, results in a doubling of the restoring force provided by the bushing for a given displacement in that direction. In contrast, doubling of H:

• Results in a doubling of the restoring force for bushings whose force-displacement characteristics are linear.

• Results in a nonlinear change of the restoring force for bushings whose force-displacement characteristics are nonlinear.

yi qi' vi yi qi ki qi = =


98

where:

Note that is a necessary condition for all n.

A typical characteristic from this formulation looks similar to the following:

Figure 1 Example Piecewise Linear Force-Displacement Characteristic

qi - The i-direction component of the (transformed) bushing displacement

- The lth stiffness for the ith direction

- The breakpoint where the stiffness changes between and

m - The number of straight-line slopes that describe the characteristic

y q v y q k1q kl 1+ kl– q bl–

l 1=

m 1–

q bl

+= =

kil

bil ki

l 1–ki

l

bil 1+

bil


Smoothed Piecewise Linear

The smoothed piecewise linear definition is similar to the piecewise, but with smoothing across each change in slope, such that the gradient of the force-displacement curve (for example, the stiffness) becomes continuous:

with:

where (noting that for clarity, the subscript i, indicating direction, has been dropped):

This gradient is integrated analytically from zero displacement q, to find the force-displacement curve. The constant of integration is set such that if there were no smoothing, the curve would pass through the origin. As smoothing is introduced, this constant of integration (the vertical offset of the force-displacement curve) is adjusted such that the smoothed curve continues to overlay the unsmoothed curve in regions where there is no smoothing (such as those for high values of displacement). Note that this means that if the origin is contained within a smoothing interval, then the smoothed force-displacement curve may not pass exactly through the origin, but that you can safely vary the smoothing interval, knowing that as the displacement moves from a smoothed into an unsmoothed region, the behavior will converge to that of the unsmoothed piecewise curve.

Note that as with the piecewise formulation, is a necessary condition for all n. Setting e to

zero collapses this formulation to the piecewise formulation.

q - The (transformed, scaled and offset) bushing displacement

kl - The lth stiffness

bl - The breakpoint (value of displacement) where the stiffness changes between and

e - The displacement over which each change in stiffness is smoothed to prevent discontinuities in stiffness

m - The number of straight-line slopes that describe the underlying characteristic

dyspw

dq------------- k1 kl 1+ kl–

0

l2

3 2l–

1

l 1=

m 1–

+=

l 0

0 l 1

l 1

l

q ble2---–

–

e----------------------------=

kil 1–

kil

bil 1+

bil


100

A typical characteristic from this formulation will look similar to the following (where the plot shows the effect of varying the smoothing interval from 0.3 mm to 10 mm):

Figure 2 Example Force-Displacement Characteristic for a Smoothed Piecewise Linear Bushing

AKIMA Spline

The nonlinear, AKIMA spline characteristic is defined using a single Adams AKIMA spline. The restoring force is than determined directly from this spline:

Hysteretic (Dual-Spline)

The hysteretic definition of the stiffness characteristic also incorporates some damping (velocity-dependence) of the force, according to the following:

where:

yi qi' vi yi qi AKISPL qi 0 IDi = =

yi qi' vi AKISPL qi vi IDi =


with:

where:

Such that, for v < -v, the force_neg_vel_values only are used, and for v > vel_threshold, only the force_pos_vel_values are used. When v is between these values, the two force characteristics are interpolated according to the STEP function described above.

Note that for very large values of P, the hysteresis disappears, and the characteristic approaches a simple displacement-dependent AKIMA spline:

Ai - Horizontal (velocity) scaling for the ith direction (vel_scale)

Ei - Velocity offset for the ith direction (vel_offset)

Pi - Velocity saturation point (m/s) for the i direction (for hysteretic bushings only)

pi - Scaled and offset velocity in the i direction

- Velocity (rate of change of model bushing displacement) in the i direction

vi - Transformed, and saturated

vi STEP pi P– 1 P 1 – =

pi Ai x· i Ei–=

x· i

x· i

yi qi' vi yi qi AKISPL qi 0 IDi =


102

The following is an example of the typical behavior of a hysteretic bushing, excited to increasing amplitude:

Damping Forces Computation

Adams/Solver computes the damping forces based on a transformed (scaled, and offset) bushing velocity vector, p, defined as:

where the Adams internal variables are:

- Rate of change of the true bushing displacement, x

Pi - Scaled and offset bushing velocity (the point in the force lookup)

Displacement Force



This formulation allows the elements of the true velocity vector, , to be scaled up by a user-specified

factor H, and/or offset by a user-specified displacement d, to determine the transformed displacement vector q, which is used as the lookup point in the definition of the stiffness force characteristic for the bushing.

For each direction, the damping force, c is given by:

where the user-specified constant:

Bi - Is the vertical (force) scaling for the ith direction (damping_force_scale)

Expressing the Damping Force Characteristic

You can use several methods to specify the damping properties in each coordinate direction, as explained next.

None

This option simply deactivates damping for the given coordinate direction:

Linear

The linear characteristic is straightforward, and is defined using a damping constant, c:

For a linear characteristic, the parameter damping_value should be set equal to the required stiffness, c.

Ai - Horizontal (velocity) scaling for the ith direction (vel_scale)

Ei - Velocity offset for the ith direction (vel_offset)


104

AKIMA Spline

The nonlinear, AKIMA spline characteristic is defined using a single Adams AKIMA spline. The damping-force characteristic is then determined directly from this spline:

Piecewise Linear

The piecewise linear characteristic is defined as:

where:

Note that is a necessary condition for all n.

qi - The i-direction component of the (transformed) bushing displacement

- The lth stiffness for the ith direction

- Breakpoint where the stiffness changes between and


A typical characteristic from this formulation will look similar to the following:

Figure 3 Example Piecewise Linear Force-Velocity Characteristic

Stiffness Fraction ("k-fraction")

The stiffness fraction damping method simply ensures that the damping coefficient increases in proportion to the local stiffness of the bushing at the current operating point.

The damping force in each direction is determined by first identifying the local stiffness as being the modulus of the rate of change of the stiffness force in that direction with respect to a displacement in the same direction. This stiffness magnitude is then multiplied by the k-fraction, k, (damping_value) and multiplied by the appropriate component of the transformed velocity, p:

For an uncoupled linear bushing (D = 0 or 1, stiffness_type = 1), this reduces to a constant damping coefficient and a typical viscous damping characteristic.

Learn how the stiffness damping characteristics are expressed in the .adm file.

Bushing Specifications in the Adams Dataset (.adm)

• Coupling Specification


106

• Stiffness Force Characteristic

• Damping Force Characteristic

Bushings are implemented using a FIE(ld)SUB. This FIESUB reads the bushing specifications directly from the .adm deck, and returns the total (stiffness plus damping) force, fi + ci, for any six-element bushing displacement and six-element bushing velocity vector.

Coupling Specification

The value of D for the bushing is specified directly as shape in the FIELD statement for the bushing:

FIELD/id, I=idi, J=idj, FUNCTION=USER(branch, shape, txa, tya, tza, rxa, rya, rza)

where the value of the integer shape may be:

Note that the selected shape factor (coupling) always applies to both the translational and rotational behavior of the bushing.

The next six parameters in the FIELD statement, all of which are required, should contain the Adams array IDs of the arrays containing the data, which expresses the stiffness and damping characteristic for the direction:

FIELD/id, I=idi, J=idj, FUNCTION=USER(branch, shape, txa, tya, tza, rxa, rya, rza)

Each of the referenced arrays must be included in the .adm file, and should be in the following form:

All of those parameters are required, and are described in detail in the following sections.

0 - Rectangular (no coupling). The force in each direction is dependent only on the displacement in that direction.

2 - Cylindrical (that is, x-y coupling). The forces in the x and y directions are each dependent on the displacement of the bushing in both the x and y directions. The force in the z direction is independent (that is, it depends only on the displacement in z).

3 - Spherical (that is, x-y-z coupling). The force in each direction depends on the displacements in all translational directions, and the torque in each direction depends on the angular displacements in all rotational directions.

ARRAY/id, NUM= stiffness_type, stiffness_value, stiffness_force_scale, …

damping_type, damping_value, damping_force_scale, …

force_offset, disp_offset, disp_scale, vel_offset, vel_scale


Stiffness Force Characteristic

You can use a number of formulations to express the stiffness force characteristic of the bushing, by appropriately setting the integer value of stiffness_type (see above), and providing the necessary data in the .adm file.

Linear (stiffness_type = 1)

For a linear characteristic, the parameter stiffness_value should be set equal to the required stiffness, k.

Piecewise Linear (stiffness_type = 4)

When you select this stiffness type, you must provide an additional array in the .adm file, and you must set the value of stiffness_value (see above) equal to the integer Adams ID of that additional array. That additional array must be of the form:

ARRAY/id, NUMBERS = n, k(0), b(1), k(1), ... , b(n), k(n)

where:

Note that the set k(0), b(1), k(1), ... , b(n), k(n) must contain precisely 2n-1 values, so that the total number of elements in the array must be 2n.

Smoothed Piecewise Linear (stiffness_type = 5)

When you select this stiffness type, you must provide an additional array in the .adm file, and you must set the value of stiffness_value (see above) equal to the integer Adams ID of this new array. For the smoother piecewise characteristic, the new array must be of the form:

ARRAY/ID, NUMBERS = s, n, k(0), b(1), k(1), ... , b(n), k(n)

n - The number of slopes that define the stiffness characteristic. This number must be an integer and greater than 1 (note that for bushings with a single slope defining the stiffness characteristic, the linear stiffness type, stiffness_type = 1, should be used)

b(1) ... b(n) - The breakpoints. The values of displacement, or of angular displacement, at which the slope changes. These values must be real and in ascending order, but may be negative.

b(m) - The breakpoint where the slope (stiffness) changes from k(m-1), for displacements lower than b(m), and to k(m) for displacements greater than b(m).

k(0) ... k(n) - The slopes, all of which must be real and positive for a physical, passive bushing. Their units are stiffness (force/displacement) or angular stiffness (torque/angular displacement). Note that k(0) extends to minus infinity and k(n) to plus infinity.


108

where:

Note that the set k(0), b(1), k(1), ... , b(n), k(n) must contain precisely 2n-1 values, so that the total number of elements in the array must be 2n+1.

AKIMA Spline (stiffness_type = 2)

The nonlinear, AKIMA spline characteristic is defined using a single Adams AKIMA spline, specified by setting stiffness_value equal to the Adams ID of the spline. That spline must be supplied in the dataset, but can be shared among several directions and/or bushings.

Hysteretic Dual-Spline (stiffness_type = 3)

To specify this stiffness characteristic, the .adm file must include both a two-element array (whose integer ID is placed in stiffness_value), of the form:

ARRAY/id, NUM = sid, P

where the terms are defined as:

and the associated Adams spline, of the form:

SPLINE/sid,,X= [displacement_values],Y= -1.0, [force_neg_vel_values],Y= 1.0, [force_pos_vel_values]

s - The interval over which changes of slope are smoothed. This number must be a real value greater than zero, in units of displacement.

n - The number of slopes that define the stiffness characteristic. This number must be an integer and greater than 1 (note that for bushings with a single slope defining the stiffness characteristic, the linear stiffness type, stiffness_type = 1, should be used).

b(1) ... b(n) - The breakpoints. The values of displacement, or of angular displacement, at which the slope changes. These values must be real and in ascending order, but may be negative.

b(m) - The breakpoint where the slope (stiffness) changes from k(m-1), for displacements lower than b(m), and to k(m) for displacements greater than b(m).

k(0) ... k(n) - The slopes, all of which must be real and positive for a physical, passive bushing. Their units are stiffness (force/displacement) or angular stiffness (torque/angular displacement). Note that k(0) extends to minus infinity and k(n) to plus infinity.

sid - The Adams ID of the 3D spline that specifies the hysteretic characteristic

P - The (positive) velocity threshold above which the bushing characteristic becomes independent of the velocity


Damping Force Characteristic

For the stiffness characteristic, a number of methods exist for specifying the damping properties in each coordinate direction:

None (damping_type = 0)

This setting of damping_type simply deactivates damping for the given coordinate direction:

Linear (damping_type = 1)

For a linear characteristic, the parameter damping_value should be set equal to the required stiffness, c.

AKIMA Spline (damping_type = 2)

The nonlinear, AKIMA spline characteristic is defined using a single Adams AKIMA spline, specified by setting damping_value equal to the Adams ID of the spline. The damping force characteristic is then determined directly from this spline:

Note the sign convention here. Within the spline definition, an increase in x (transformed velocity) should generally yield an increase in the y value (damping force).

The same Adams AKIMA spline can be used for more than one direction of the same bushing (optionally, with different scaling), and/or for more than one instance of a bushing within the same model.

Piecewise Linear (damping_type = 3)

When you select this damping type, exactly as with the equivalent stiffness type, you must provide an additional array in the .adm file, and you must set the value of damping_value (see above) equal to the integer Adams ID of that additional array. That array must be of the form:

ARRAY/id, NUMBERS = n, k(0), b(1), k(1), ... , b(n), k(n)

where:

n - The number of slopes that define the damping characteristic. This number must be an integer, and greater than 1 (note that for bushings with a single slope defining the damping characteristic, the linear damping type, damping_type = 1, should be used).

b(1) ... b(n) - The breakpoints. The values of velocity, or of angular velocity, at which the slope of the damping characteristic changes. These values must be real and in ascending order, but may be negative.


110

Note that the set c(0), b(1), c(1), ... , b(n), c(n) must contain precisely 2n-1 values, so that the total number of elements in the array must be 2n.

Stiffness Fraction ("k-fraction") (damping_type = 4)

For the stiffness-fraction damping characteristic, the parameter damping_value should be set equal to the required stiffness fraction, k.

b(m) - The breakpoint where the slope (damping coefficient) changes from c(m-1), for velocities lower than b(m), to c(m) for velocities greater than b(m)

c(0) ... c(n) - The slopes, all of which must be real and positive for a physical, passive bushing. Their units are those of damping (that is, force/velocity) or rotational daming (that is, torque/angular velocity). Note that c(0) extends to minus infinity and c(n) to plus infinity.

111Working with ComponentsForces

ForcesYou can build the following types of forces in Template Builder:

• Springs

• Dampers

• Bumpstops

• Reboundstops

In Template Builder you can also modify air springs.

Working with SpringsA spring element defines a force-displacement relationship between two parts. The spring force acts on the two parts at user-specified coordinates. The spring’s force-displacement properties, free length, number of coils and other parameters are given in the designated property file.

Learn about springs:

• Creating and Modifying Springs

• About Linear Springs

• About Nonlinear Springs

• About Spring Property Files

Your template-based product models air springs as simple action-reaction forces between two parts. Each air spring references an air-spring property file that tabulates spring force against trim load and deflection from trim length. Trim load is the nominal load in the spring for a given trim length and internal pressure. Before analysis, your template-based product reads the data from the referenced property file and stores it in a three-dimensional SPLINE. During analysis, Adams/Solver computes the air-spring force by interpolating the SPLINE data using the Akima method.

Air springs include an auto-trim feature, where you can specify a desired trim height of the suspension and the air spring's trim load is automatically adjusted during static equilibrium analysis to achieve the trim height.

To use an air spring in a subsystem, select a coil spring and use the replace option from the shortcut menu to replace the coil spring with an air spring.

Learn about air springs:

• Modifying Air Springs

• Auto Trim Load

• Calculation of Air-Spring Force

Adams/CarForces

112

Creating and Modifying Springs

When working in Template Builder, you can create springs and then modify them. When working in Standard Interface, you can only modify springs. Learn about the interface modes.

Nonlinear Springs

To create a nonlinear spring:

1. From the Build menu, point to Forces, point to Spring, and then select New.

2. Press F1 and then follow the instructions in the dialog box help for Create/Modify Spring.

3. Select OK.

To modify a nonlinear spring in the Template Builder:

1. To display the modify dialog box, do one of the following:

• From the Build menu, point to Forces, point to Spring, and then select Modify. To load the parameters for a specific spring, you must specify the spring you want to modify.

• Right-click a spring, point to its name, and then select Modify. The dialog box has the spring parameters already loaded.

2. Press F1 and then follow the instructions in the dialog box help for Create/Modify Spring.

3. Select OK.

To modify a nonlinear spring in the Standard Interface:

1. In Standard Interface, right-click a spring, point to its name, and then select Modify. The dialog box has the spring parameters already loaded.

2. Press F1 and then follow the instructions in the dialog box help for Modify Spring.

3. Select OK.

Linear Springs

To modify a linear spring in the Standard Interface:

1. Right-click a spring, point to its name, and then select Modify. The dialog box has the spring parameters already loaded.

2. Press F1 and then follow the instructions in the dialog box help for Modify Linear Spring.

3. Select OK.

About Linear Springs

Your template-based product (using the Adams/Solver SPRINGDAMPER) calculates the spring force as follows:

Spring Force = - K*(DM(I,J) - OffsetCalc)where:


• K - The linear stiffness defined in the spring property file.

• DM - The instantaneous distance between the I and J coordinate references.

• OffsetCalc - Depends on the free length defined in the spring property file and in the spring install methods.

Spring Install Methods

The three spring install methods are:

• Preload - The desired spring load at the current position of the I and J coordinate references.

• Installed Length - The installed length of the spring at the current position of the I and J coordinate references.

• Use Hardpoints - The installed length of the spring equals the distance between the I and J coordinate references.

When you submit the model to Adams/Solver, the spring-damper statement that your template-based product creates, has the form:

SPRINGDAMPER/id, I=I_id, J=J_id, K=K, C=0, LENGTH=OffsetCalc, FORCE=0, TRANSLATIONAL

About Nonlinear Springs

Your template-based product (using the Adams/Solver SFORCE) interpolates a force versus spring length or spring deflection table using Akima's method.

If you are using a force versus length table, the force is calculated as follows:

Spring Force = AKISPL(OffsetCalc + DM(I, J), 0, Spline)

If you are using a force versus deflection table, the force is calculated as follows:

Spring Force = AKISPL(OffsetCalc - DM(I, J), 0, Spline)where:

• AKISPL - Adams/Solver function that interpolates data stored in a SPLINE.

• OffsetCalc - Depends on the free length defined in the spring property file and in the spring install methods.

• DM - The instantaneous distance between the I and J coordinate references.

• Spline - A reference to a SPLINE statement.

Spring Install Methods

The three spring install methods are:

Adams/CarForces

114

• Preload - The desired spring load at the current position of the I and J coordinate references.

• Installed Length - The installed length of the spring at the current position of the I and J coordinate references.

• Use Hardpoints - The installed length of the spring equals the distance between the I and J coordinate references.

When you submit the model to Adams/Solver, the SFORCE statement that your template-based product creates, has the form:

SFORCE/id, I=I_id, J=J_id, FUNCTION=AKISPL(OffsetCalc + DM(I_id, J_id), 0, Spline)\, TRANSLATIONAL

About Spring Property Files

The spring component supports the following types of Property Files:

• TeimOrbit linear-spring property files (extension .lsf). See TeimOrbit File Format. Learn more about this file format with the help of Spring dialog box.

• TeimOrbit nonlinear-spring property files (extension .spr). Standard TeimOrbit nonlinear-spring property files correspond to nonlinear, deflection-based spring formulation, as explained in About Nonlinear Springs.

• XML spring property file (See XML File Format). The XML spring property file supports linear and nonlinear force characteristics and allows you to choose between specifying force versus spring deflection or spring length, as described in About Nonlinear Springs. You work with XML files in the Property File Editor.

Modifying Air Springs

To modify an air spring in the Standard Interface:

1. In Standard Interface, right-click an air spring, point to its name, and then select Modify. The dialog box has the air-spring parameters already loaded.

2. Press F1 and then follow the instructions in the dialog box help for Modify Spring.

3. Select OK.

Auto Trim Load

An Adams/Solver differential equation sets an air spring's trim load. The differential equation calculates the trim load that corresponds to the desired trim length during static equilibrium analyses. Its value is then locked to the last value calculated during static analyses for all the subsequent transient simulations.

F = USER (1117, trimLength, Imarker, Jmarker)where:

• 1117 - Branch ID


• trimLength - The desired displacement, as specified in the property file, which you can edit using the Property File Editor.

• I/J marker - The air spring's I and J markers of the SFORCE.

Calculation of Air-Spring Force

An Adams/Solver SFORCE computes the air-spring force. The SFORCE function is:

force = AKSIPL((trimLength – DM (marker I, marker j)), (trimLoad), splineID)

where:

• AKSIPL - Is the Adams/Solver function that interpolates data using Akima’s method.

• trimLength - Is the distance between the upper and lower spring seats when the suspension is at trim height. trimLength is a positive real value read from the air-spring property file.

• DM(marker I, marker J) - Is the distance between the upper and lower spring seats.

• TrimLoad is the load in the spring when the suspension is at trim height. The load corresponds to the trim load you specified, or, if you select auto trim load, it corresponds to a differential equation.

Working with DampersA damper defines the force-velocity relationship between two parts. The damper is defined as acting between user-specified Coordinate Reference points on each part, and conforms to the force-velocity curve described in the designated property file.

Learn about dampers:

• Creating and Modifying Dampers

• About Linear Dampers

• About Nonlinear Dampers

Creating and Modifying Dampers

When working in Template Builder, you can create dampers and then modify them. When working in Standard Interface, you can only modify dampers. Learn about the interface modes.

Nonlinear Dampers

To create a nonlinear damper:

1. From the Build menu, point to Forces, point to Damper, and then select New.

2. Press F1 and then follow the instructions in the dialog box help for Create/Modify Damper.

3. Select OK.

Adams/CarForces

116

To modify a nonlinear damper in the Template Builder:

• To display the modify dialog box, do one of the following:

• From the Build menu, point to Forces, point to Damper, and then select Modify. To load the parameters for a specific damper, you must specify the damper you want to modify.

• Right-click a damper, point to its name, and then select Modify. The dialog box has the damper parameters already loaded.

• Press F1 and then follow the instructions in the dialog box help for Create/Modify Damper.

• Select OK.

To modify a nonlinear damper in the Standard Interface:

1. Right-click a damper, point to its name, and then select Modify. The dialog box has the damper parameters already loaded.

2. Press F1 and then follow the instructions in the dialog box help for Modify Damper.

3. Select OK.

Linear Dampers

To modify a linear damper in the Standard Interface:

1. Right-click a damper, point to its name, and then select Modify. The dialog box has the damper parameters already loaded.

2. Press F1 and then follow the instructions in the dialog box help for Modify Linear Damper.

3. Select OK.

About Linear Dampers

In addition to the standard definition of a damper (based on an AKIMA spline interpolation of a force velocity two-dimensional spline), Adams/Car offers a linear-damper model. The linear-damper model allows you to define a single damping term. The force exerted by the damper between the I and J parts at the desired locations follows the well-known formula:

Force = -c dx/dt

where dx/dt is the time derivative of the radial relative displacement between marker I and marker J.

About Nonlinear Dampers

The force-velocity formula is based on:

• VR - Relative velocity of marker I with respect to marker J

• Damper property file

Force = akispl(VR(marker i, marker j),0, Spline)


The damper property file defines the two-dimensional spline. The independent variable is the translational velocity of the I and J markers, and the dependent variable is the force exerted between the two parts at the I and J marker locations.

You can also specify gas preload force for nonlinear dampers using XML-format property files.

To specify gas preload:

1. Right-click a damper, point to its name, and then select Modify.

The Modify Damper dialog box appears.

2. Specify an XML property file.

3. Select the Curve Manager tool .

4. Select the Properties tab.

5. Under Gas Preload, select one:

• None - No preload is added to the damper force calculations.

• Constant - A constant force is added to damper force calculations.

• Nonlinear - Preload is calculated by interpolating a spline. The independent value of the spline is the relative displacement between the I and J markers.

Working with BumpstopsA bumpstop defines a force-displacement relationship between two parts. The bumpstop acts between user-specified coordinate reference points on each part, and conforms to the force-displacement properties described in the designated property file.

The bumpstop force is activated when the displacement between the two coordinate references exceeds the clearance defined for the bumpstop.

The force-displacement formula is based on:

• Instantaneous distance between the user-specified coordinates defined on each part

• Impact length or clearance

• Bumpstop property file (polynomial or nonlinear stiffness with or without linear or nonlinear damping).

Learn about bumpstops:

• Creating and Modifying Bumpstops

• Calculation of Force Characteristics

• About Bumpstop Property Files

Creating and Modifying Bumpstops

When working in Template Builder, you can create bumpstops and then modify them. When working in Standard Interface, you can only modify bumpstops. Learn about the interface modes.

Adams/CarForces

118

To create a bumpstop:

1. From the Build menu, point to Forces, point to Bumpstop, and then select New.

2. Press F1 and then follow the instructions in the dialog box help for Create/Modify Bumpstop.

3. Select OK.

To modify a bumpstop in the Template Builder:


• From the Build menu, point to Forces, point to Bumpstop, and then select Modify. To load the parameters for a specific bumpstop, you must specify the bumpstop you want to modify.

• Right-click a bumpstop, point to its name, and then select Modify. The dialog box has the bumpstop parameters already loaded.

• Press F1 and then follow the instructions in the dialog box help for Create/Modify Bumpstop.

• Select OK.

To modify a bumpstop in the Standard Interface:

• In Standard Interface, right-click a bumpstop, point to its name, and then select Modify. The dialog box has the bumpstop parameters already loaded.

• Press F1 and then follow the instructions in the dialog box help for Modify Bumpstop.

• Select OK.

Calculation of Force Characteristics

The XML (XML File Format) bumpstop property file supports various methods and options for calculating force characteristics. It supports the following methods to determine the elastic-force component:

• polynomial - The formulation of the force is based on a third-order polynomial whose equation can be expressed as follows:

F elastic = POLY(MAX(0, impact_length – DM ( marker i, marker j )), 0,0, LinearRate, QuadraticRate, CubicRate)

• nonlinear (spline based) - The formulation of the force is based on the Akima spline interpolation of a nonlinear characteristic:

F elastic = akispl(MAX(0, impact_length - DM( marker i, marker j )), 0,

Spline)

The elastic force becomes active only when the instantaneous distance between the markers on the two parts is less than the impact length. The impact length term depends on the distance type. If you select Clearance, the impact length becomes:

dmCalc - Clearancewhere:

• Clearance - Value you specify

• dmCalc - Initial displacement computed between the I and J markers


The following figure shows the clearance and impact length.

In an XML bumpstop property file, you can also enable a damping characteristic. If you enable the damping characteristic, the force is dependent on the deflection and velocity of the I and J markers.

Damping (viscous) forces can be:

• linear - If you include in the property file a linear damping value other than zero, then the total force exerted between the I and J parts is equal to the sum of the elastic force specified above and the following damping force:

Fdamping = STEP MAX(0, impact_length - DM(i,j)), 0, 0, 0.1, -dampingRate * VR ( marker i, marker j ))

• nonlinear (spline based) - If you include in the property file a nonlinear damping value, then the total force exerted between the I and J parts is equal to the sum of the elastic force specified above and the following damping force:

F damping = STEP MAX(0, impact_length - DM(i,j)), 0, 0, 0.1, -

Adams/CarForces

120

AKISPL ( VR ( marker i, marker j ), 0, dampingSpline ))

About Bumpstop Property Files

The bumpstop component supports the following types of property files:

• TeimOrbit (TeimOrbit File Format) bumpstop property files (extension .bum). Standard TeimOrbit bumpstop property files correspond to nonlinear elastic forces with linear damping equal to 0 formulation. Learn more with Bumpstop dialog box help.

• XML (XML File Format) bumpstop property file. The XML bumpstop property file enables data sharing with other MSC.Software applications, such as Adams/Chassis, and allows greater flexibility and a wider range of bumpstop formulation choices. In particular, the new XML bumpstop property file supports various methods and options for the calculation of force characteristics, as explained in Calculation of Force Characteristics. You work with XML files in the Property File Editor.

Working with ReboundstopsA reboundstop defines a force-displacement relationship between two parts. The reboundstop acts between user-specified coordinate reference points on each part, and conforms to the force-displacement curve described in a designated property file. The reboundstop force is activated when the displacement between the two coordinate references exceeds the defined clearance.

The force-displacement formula is based on:

• Instantaneous distance between the user-specified coordinates defined on each part

• Impact length or clearance

• Reboundstop property file (polynomial or nonlinear stiffness with or without linear or nonlinear damping.)

Learn about reboundstops:

• Creating and Modifying Reboundstops

• Calculation of Force Characteristics

• About Rebounstop Property Files

Creating and Modifying Reboundstops

When working in Template Builder, you can create reboundstops and then modify them. When working in Standard Interface, you can only modify reboundstops. Learn about the interface modes.

To create a reboundstop:

• From the Build menu, point to Forces, point to Reboundstop, and then select New.

• Press F1 and then follow the instructions in the dialog box help for Create/Modify Reboundstop

• Select OK.


To modify a reboundstop in the Template Builder:


• From the Build menu, point to Forces, point to Reboundstop, and then select Modify. To load the parameters for a specific reboundstop, you must specify the reboundstop you want to modify.

• Right-click a reboundstop, point to its name, and then select Modify. The dialog box has the reboundstop parameters already loaded.

• Press F1 and then follow the instructions in the dialog box help for Create/Modify Reboundstop.

• Select OK.

To modify a reboundstop in the Standard Interface:

• In Standard Interface, right-click a reboundstop, point to its name, and then select Modify. The dialog box has the reboundstop parameters already loaded.

• Press F1 and then follow the instructions in the dialog box help for Modify Reboundstop.

• Select OK.

Force Calculation

The force in a rebound stop always acts to keep two parts from moving farther apart. The force is active only when the distance between the parts as computed by dm(i,j) exceeds the impact length. You specify the impact length directly or indirectly as the initial clearance in the rebound stop. When you specify a clearance, the impact length is calculated from the clearance as follows:

dmCalc + Clearancewhere:

• Clearance is the value you specify

• dmCalc is the initial displacement computed between the i and j markers

Further, the force in a rebound stop is the sum of an elastic force and a damping force. The XML property file supports various options for calculating either force. The options available for calculating elastic force (F elastic) are:

• polynomial - The for calculated using a third-order polynomial. The Adams/Solver function expression is:

F elastic = POLY(MAX(0,DM(i, j) - impact_length),0,0,- linearRate,-quadraticRate,-cubicRate)

• nonlinear (spline based) - The force is interpolated using Akima's method based on force vs. deflection data.

F elastic = -1.0*(AKISPL(MAX(0,DM( i , j ) - impact_length),0,Spline))

Adams/CarForces

122

The following figure shows the clearance and impact length.

The damping force always acts in opposition to the velocity. In an XML (XML File Format) reboundstop property file, the options for calculating damping force are:

• linear - You specify the dampingRate, and the damping force is the product of dampingRate, velocity, and a STEP function. The STEP function depends on the displacement in the rebound stop and ensures the damping force is continous with displacement.

Fdamping = STEP (MAX(0, DM(I,J) - impact_length), 0, 0, 0.1, -dampingRate* VR ( marker i, marker j ))

• nonlinear (spline based) - The damping force is interpolated using Akima’s method from a table of force vs. velocity. Again, a STEP function dependent on the displacement in the rebound stop ensure that the damping force is continous with displacement.

F damping = STEP (MAX(0, DM(I,J) - impact_length), 0, 0, 0.1, -AKISPL VR ( marker i, marker j ), 0, dampingSpline ))

About Reboundstop Property Files

The reboundstop component supports the following types of property files:


• TeimOrbit (TeimOrbit File Format) reboundstop property files (extension .reb) - Standard TeimOrbit reboundstop property files correspond to nonlinear elastic forces with linear damping equal to 0 formulation. Learn more with Reboundstop dialog box help.

• XML (XML File Format) reboundstop property file - The XML reboundstop property file enables data sharing with other MSC.Software applications, such as Adams/Chassis, and allows greater flexibility and a wider range of reboundstop formulation choices. In particular, the new XML reboundstop property file supports various methods and options for the calculation of force characteristics, as explained in Calculation of Force Characteristics. You work with XML files in the Property File Editor.

Adams/CarWheels, Adjustable forces and Gears

124

Wheels, Adjustable forces and Gears

Wheels A wheel is a specialized part you can use when creating tire models. In Adams/Car, creating a wheel corresponds to creating the metal rigid body part (the rim) and the rubber (tire) around it. You model the rim with a general rigid part and the tire with a general force (GFORCE). For information on GFORCE, see the Adams/Solver online help.

In Standard Interface, to modify a wheel:

1. Right-click a wheel, and then select Modify.

2. Press F1 and then follow the instructions in the dialog box help for Modify Wheel.

3. Select OK.

In Template Builder, to create or modify a wheel:

1. From the Build menu, point to Wheel, and then select New/Modify.

2. Press F1 and then follow the instructions in the dialog box help for Create/Modify Wheel.

3. Select OK.

Adjustable ForcesAn adjustable force is a special Template Builder user-defined element (UDE). You can use adjustable forces for a variety of conditions, to satisfy static parameters in your model. For example, if you want to set the length of a rod to be a specific length during static analysis, the adjustable force will vary until the desired end condition is satisfied.

In Adams/Car for example, a typical application is to use an adjustable force to set toe and camber values during a static suspension analysis. You might use two parts to define the tie rod and attach them by a translational joint. You would then apply an adjustable force between the two parts to set toe and camber values.

When the vehicle reaches static equilibrium without the use of adjustable forces, the toe and camber alignments might not be the ones that you want. You use adjustable forces to define toe and camber angles at static equilibrium position.

Adjustable forces act between two appropriate parts and perform a series of adjustments during static equilibrium to minimize the error between the current computed toe/camber angle and the desired toe/camber.

You might, for example, use two parts for the tie rod, constrain them using a translational joint, and then apply an adjustable force between the two parts to set static toe angle. The current formulation creates a single-component force that acts between the two parts. The force function uses stiffness and damping values that you can set. The user-defined force uses a differential equation to minimize the error between desired and computed angles.

../adams_solver/master.htm

125Working with ComponentsWheels, Adjustable forces and Gears

The _double_wishbone_torsion template distributed in the shared car database contains an example of an adjustable force.

If more than one adjustable force is defined in a model, you must use the pattern statement within the adjustable force definition. The pattern statement defines the order in which adjustable forces are active. The following table defines four adjustable forces.

In Pattern 1, two separate static analyses would be run. In the first analysis, the toe adjustable forces would be active. During the second analysis, the camber adjustable forces would be active. In Pattern 2, four separate static analyses would be run and the same order as in Pattern 1 would be repeated. Because the camber is directly affected by the toe change and the toe change is affected by the camber, it is often desirable to build up patterns such that you can find a static solution by running a number of separate static analysis. Pattern 3 is an example of eight separate static analyses.

Once the static analysis has been run, one of two things will happen depending on whether the lock with motion was set for the adjustable force. For example, in Adams/Car an adjustable force might be created between the tie rod inner and tie rod outer parts. If the adjustable force is locked with motion, then after the statics is complete, Adams/Car will create a fixed joint between the two tie rod parts, fixing the displacement between these parts for subsequent dynamic analyses. But if the adjustable force is not locked, then the same force between the tie rod parts at the end of the static analysis will be maintained during subsequent dynamic analyses.

In Standard Interface, to modify an adjustable force:

1. From the Adjust menu, select Adjustable Force.

2. Press F1 and then follow the instructions in the dialog box help for Modify Adjustable Force.

3. Select OK.

In Template Builder, to create or modify an adjustable force:

1. From the Build menu, point to Adjustable Force, and then select New/Modify.

2. Press F1 and then follow the instructions in the dialog box help for Create/Modify Adjustable Force.

Adjustable force: Pattern 1: Pattern 2: Pattern 3:

Front left toe 10 1010 10101010

Front right toe 10 1010 10101010

Front left camber 01 0101 01010101

Front right camber 01 0101 01010101

Rear left toe 10 1010 10101010

Rear right toe 10 1010 10101010

Rear left camber 01 0101 01010101

Rear right camber 01 0101 01010101

Adams/CarWheels, Adjustable forces and Gears

126

3. Select OK.

GearsWe provide two constraint-based gear options within the Template Builder:

• Differential gear - The differential gear applies a reduction ratio between an input joint and the symmetric output joint pair. The joint can be either revolute or cylindrical. The motion direction can be inverted between the input and output joints and a toggle exists to switch between the two different modes, allowing the reduction ratio to always be positive.

The reduction ratio is based on the following equation:

input motion = reduction ratio * (input shaft - output shaft)/2You can define the differential gear to be kinematically active, allowing the element to be turned on or off depending on the type of analysis you are running: compliant or kinematic.

• Reduction gear - The reduction gear applies a reduction ratio between the input and output joint. Either joint type can be translational, revolute, or cylindrical. Additionally, the motion direction can be inverted between the input and output joints and a toggle exists to switch between the two different modes, allowing the reduction ratio to always be positive.

When you enter a cylindrical joint in the input or output Joint text box, an additional text box becomes active. Because either the rotational or translational degree of freedom of the cylindrical joint can be used, you must specify if the rotational or translational motion will be the output for the gear.

The reduction ratio is based on the following equation:

input motion = reduction_ratio * output motion

You can define the differential gear as being kinematically active, allowing the element to be turned on or off depending on the type of analysis you are running: compliant or kinematic.

Note: A gear in Adams/Car is a coupler in Adams/View.

127Working with ComponentsActuators

ActuatorsWe provide several actuator options with the Template Builder. An actuator lets you define an element that can apply a force or motion function to a collection of modeling components. For example, you might want to create a motion on a valvetrain system, or steer a vehicle around a corner. These components include joints and parts but are not limited only to these.

Learn more about actuators:

• About Actuators

• Joint-Force Actuators

• Joint-Motion Actuators

• Point-Point Actuators

• Point-Torque Actuators

• Variable Actuators

• Set Function

• Set Activity

About ActuatorsWhen used with appropriate feedback channels, actuators provide a very powerful method to control your system.

Actuators differ from adjustable forces due to their behavior during dynamic analyses, with actuators remaining active, whereas adjustable forces are either locked in place or replaced by a fixed joint.

If you create actuators as a symmetrical pair, then you can define separate left and right functions. You can use the Function Builder to define functions.

Each actuator can have an application area and an identifier. The application area provides information about the intended purpose of the actuator. The identifier should be used to describe the actuator instance for this application area. A typical example would be:

Application area = steeringIdentifier = steering_wheel_angle (e.g. for a motion type actuator)

These two additional parameters support a more dynamic use of actuators. For example, to allow de-/activation and function assignment on the assembly level by adding additional means for browsing and filtering. Note that they are currently not required by your template-based product.

You can define limits for each actuator in the same way that you would define limits in a test laboratory to prevent damage caused by excessive actuator force or travel. Although you can define limits for force, displacement, velocity, and acceleration, it is not required that you do so.

Adams/CarActuators

128

You can define the activity of the actuator as either active or not active. You can define the activity either from the dialog box or from the menu option Set Activity located under the Actuators menu. Learn about defining the activity.

Joint-Force ActuatorsA joint-force actuator defines either a translational or rotational Single-Component Force acting between two parts that a user-defined joint connects. You can select three types of joints:

• Revolute joint - Selecting a revolute joint causes the Template Builder to automatically switch to rotational and disable the Type of Freedom option. The single-component force will be a rotational force acting between the two bodies that the revolute joint connects.

• Translational joint - Selecting a translational joint causes the Template Builder to automatically switch to translational and disable the Type of Freedom option. The single-component force will be a translational force acting between the two bodies that the translation joint connects.

• Cylindrical joint - Selecting a cylindrical joint makes an additional text box active. Because either the rotational or translational degree of freedom of the cylindrical joint can be used, you must specify if the rotational or translational force will be used. This allows you to decide between the creation of a torque or a force, based on the selection of either the rotational or translational type of freedom.

Learn more about actuators, such as creating symmetrical pairs, using application area and identifier attributes, and defining limits.

To create/modify a joint-force actuator:

1. From the Build menu, point to Actuators, point to Joint Force, and then select New/Modify.

2. Press F1 and then follow the instructions in the dialog box help for Create/Modify Joint Force Actuator.

3. Select OK.

Point-Point ActuatorsA point-point actuator defines an action-reaction translational single-component force acting between the two parts that I Part and J Part parameters specify. You define the direction of the resulting force by selecting the two points of force application, which can be either hardpoint or construction frame locations.


To create/modify a point-point actuator:

1. From the Build menu, point to Actuators, point to Point Torque, and then select New/Modify.

129Working with ComponentsActuators

2. Press F1 and then follow the instructions in the dialog box help for Create/Modify Point Point Actuator.

3. Select OK.

Joint-Motion ActuatorsA joint-motion actuator defines either a translational or rotational motion acting between two parts that a user-defined joint connects. You can select three types of joints:

• Revolute joint - Selecting a revolute joint causes the Template Builder to automatically switch to rotational and disable the Type of Freedom option. The motion will be a rotational motion acting between the two bodies that the revolute joint connects.

• Translational joint - Selecting a translational joint causes the Template Builder to automatically switch to translational and disable the Type of Freedom option. The motion will be a translational motion acting between the two bodies that the translational joint connects.

• Cylindrical joint - Selecting a cylindrical joint makes an additional text box active. Because either the rotational or translational degree of freedom of the cylindrical joint can be used, you must specify if the rotational or translational motion will be used. This allows you to decide between the creation of a rotational or a translational motion based on selection of either the rotational or translational type of freedom.


To create/modify a joint-motion actuator:

1. From the Build menu, point to Actuators, point to Joint Motion, and then select New/Modify.

2. Press F1 and then follow the instructions in the dialog box help for Create/Modify Joint Motion Actuator.

3. Select OK.

Point-Torque ActuatorsA point-torque actuator defines an action-reaction or action-only rotational single-component torque acting between the two parts that the I Part and J Part parameters specify. You define the direction of the resulting torque within the dialog box. Many of the parametric functions discussed in Construction Frames are available to define the position and orientation of the resulting actuator.

If you define the actuator as action only, then the J Part text box is disabled and no reaction is exerted.


To create/modify a point-torque actuator:

1. From the Build menu, point to Actuators, point to Point Torque, and then select New/Modify.

Adams/CarActuators

130

2. Press F1 and then follow the instructions in the dialog box help for Create/Modify Point Torque Actuator.

3. Select OK.

Variable ActuatorsA variable actuator is a user-defined element consisting of a data element variable and a series of additional elements, such as strings and arrays. A variable actuator can be particularly useful where either parts or joints cannot be referenced. An example of a variable actuator is the velocity of a vehicle: the function could define a changing velocity which is then referenced by several other modeling components.


To create/modify a variable actuator:

1. From the Build menu, point to Actuators, point to Variable, and then select New/Modify.

2. Press F1 and then follow the instructions in the dialog box help for Create/Modify Variable Actuator.

3. Select OK.

Set FunctionYou can use the set function menu item to modify or replace the function that you defined.

You can use the Function Builder to define functions.

To set actuator function:

1. From the Build menu, point to Actuators, and then select Set Function.

2. Press F1 and then follow the instructions in the dialog box help for Actuator Set Function.

3. Select OK.

Set ActivityYou can use the set activity menu option to set the actuator to be either active or not active. The not active option is particularly useful when actuator elements are not required.

To set actuator activity:

1. From the Build menu, point to Actuators, and then select Set Activity.

2. Press F1 and then follow the instructions in the dialog box help for Actuator Set Activity.

3. Select OK.

131Working with ComponentsCondition Sensors

Condition SensorsA condition sensor is a user-defined element that consists of a data element array and strings. It references an existing variable class element (data element variable or measure solver computed), which is then tied to the label and unit strings by the array. The array also encapsulates a request (for plotting convenience) and a units conversion factor.

In essence, a condition sensor represents a relationship between a measurable solver quantity (the variable class object) and a string label identifier that can be used in an event file (.xml) to define a condition for Adams/Car full-vehicle analyses.

Use of Condition Sensors in Adams/Car

Adams/Car browses the assembly for condition sensor elements prior to each vehicle analysis and updates the data element end_conditions_array with the derived list. At the beginning of the simulation, the Standard Driver Interface (SDI) then uses the specified end condition measure string in the driver control file to identify the associated variable class object in the dataset, that calculates the quantity the end condition sensor should compare to the target value.

This architecture allows you to extend the provided set of standard end conditions. If, for example, a ramp-steer like custom vehicle event should be ended when the turn radius falls short of a certain threshold, you could:

• add a variable class element to calculate the desired turn radius

• variable name = .__MDI_SDI_TESTRIG.body_turn_radius

• function = (vx2 + vy2)1.5 / (vx*ay - vy*ax)

• add a condition sensor referencing the variable above

• label = "radius"

• variable = .__MDI_SDI_TESTRIG.body_turn_radius

• units = length

Then, you could use this new condition sensor with the following line in your driver control file:

(END_CONDITIONS){measure test value allowed_error filter_time delay_time group}'RADIUS' '|<' 20000.0 500.0 0.0 0.0

Creating or Modifying Condition Sensors

To create/modify condition sensors:

1. From the Build menu, point to Condition Sensors, and then select New/Modify.

2. Press F1 and then follow the instructions in the dialog box help for Create/Modify Condition Sensor.

3. Select OK.

Adams/CarFeedback Channels

132

Feedback ChannelsA feedback channel is a special user-defined element that contains a series of entities such as Adams/Solver measures and Adams/View variables. Creating a feedback channel effectively corresponds to creating a measure (Adams/Solver variable). It is then possible to display the measure. For information on creating, displaying, and managing strip charts based on measures, see the Adams/View online help.

Feedback channels are used in the __MDI_SUSPENSION_TESTRIG for the controller. Your template-based product creates two channels:

• Raw_channel - Controls an absolute value.

• Offset_channel - Controls desired inputs for a deviation.

You can create feedback channels either as a symmetrical pair or individually.

Each feedback channel has an application area and a unique identifier. The application area provides information about the intended purpose of the feedback channel. For example, you may want to specify an application area for engine velocity with the identifier specifying that the velocity will be at the crank. The following are possible naming schemes:

Application area = engine_velocityIdentifier = engine_velocity_crank

If you create feedback channels as a symmetrical pair, then you can define separate left and right functions. You can use the Function Builder to define functions.

You can offset the raw signal of the feedback channel by a desired real value. Entering a real number in this text box causes the Template Builder to create an additional measure whose function is the same as the raw channel, but it is offset by the specified value.

Creating or Modifying User-Function Feedback Channel

To create or modify a user-function feedback channel:

1. From the Build menu, point to Feedback Channels, point to User Function, and then select New/Modify.

2. Press F1 and then follow the instructions in the dialog box help for Create/Modify User-Function Feedback Channel.

Setting Function

You can use the set function menu to modify or replace the function that you defined. Note that you have the option to specify a routine instead of a function.

To set feedback channel function:

1. From the Build menu, point to Feedback Channels, and then select Set Function.

../adams_view/master.htm

133Working with ComponentsFeedback Channels

2. Press F1 and then follow the instructions in the dialog box help for Set Feedback Channel Function.

Setting Offset

You can use the set offset menu to modify the offset applied to the raw measured channel. You can toggle the activity of the offset on or off.

To set feedback channel offset:

1. From the Build menu, point to Feedback Channels, and then select Set Offset.

2. Press F1 and then follow the instructions in the dialog box help for Set Feedback Channel Offset.

Adams/CarData Elements, Requests and Variables

134

Data Elements, Requests and Variables

General Data ElementsGeneral data elements are elements whose values are stored in property files.

The general data elements group includes:

• General Parameter

• General Spline

• General Variable

General ParametersThe general parameter is an Adams/View variable whose real value is based on a value stored in a property file data block. The property file must be in the neutral file format of your template-based product. When your template-based product reads the property files, it updates the general parameter variable entity with the appropriate real value stored in the property file. The data block and attribute names in the Create General Parameter dialog box identify the data that is being accessed from the property file.

Adams/Car uses a general parameter to model the piston area within a steering system. The steering system includes a data block as follows:

$------------------------------------------------GENERAL_PARAMETER [GENERAL_PARAMETER] USAGE = 'rack_piston_area' SYMMETRY = 'single' PROPERTY_FILE = 'mdids://acar_shared/steering_assists.tbl/mdi_steer_assist.ste'DATA_BLOCK = 'STEERING_ASSIST' ATTRIBUTE_NAME = 'piston_area'

The parameter DATA_BLOCK refers to the sub-block (steering_assist) in which the parameter can be found. The USAGE keyword describes the name of the attribute whose value must be located. The example below shows the data for the piston_area referenced above:

$----------------------------------------------------STEERING_ASSIST[STEERING_ASSIST]piston_area <area> = 490.87

In this case, the general parameter variable (rack_piston_area) is set to 490.87.

If your template-based product does not find the specified data blocks in the selected property file, then it issues a warning and the general parameter retains its default value (0.0).

135Working with ComponentsData Elements, Requests and Variables

To create or modify a general parameter:

1. From the Build menu, point to General Data Elements, point to Parameter, and then select New/Modify.

2. Press F1 and then follow the instructions in the dialog box help for Create/Modify General Parameter.

3. Select OK.

General SplinesThe general spline is a spline whose values are stored in a property file. The property file must be in the neutral file format of your template-based product. This method of creating splines allows great flexibility: you can define the splines in your model depending on the numerical content of the selected property files. When your template-based product reads the property files, it updates the spline entities with the appropriate referenced values stored in the property files. The data that is being accessed from the property file is identified by the data block and data sub-block names in the Create General Spline dialog box. This allows for a very quick and efficient way to modify your data, without manually modifying the data within an Adams spline.

For example, you could store the boost curve characteristics of many different steering systems in separate property files and then test different steering systems by referencing those property files. If your template-based product does not find the specified data blocks in the selected property file, then it issues a warning and the spline retains its default values.

You can also create a spline using the Build -> Data Element -> Spline menus.This spline differs from the general spline in a couple of subtle different ways:

• A data element spline stores its data within the template and does not reference an external data file defined by the neutral file format (TeimOrbit). Therefore, simple changes in data require that you manually manipulate this spline in the Template Builder.

• Because you cannot make variations to the spline data within the standard user environment, you cannot carry out what-if scenarios, which you can easily do with the general spline.

Adams/Car uses a general spline to model steering characteristics. The steering subsystem includes a data block as follows:

$----------------------------------------------------GENERAL_SPLINE[GENERAL_SPLINE]USAGE = 'steering_assist'SYMMETRY = 'single'TYPE = 'two_dimensional'PROPERTY_FILE = 'mdids://acar_shared/steering_assists.tbl/mdi_steer_assist.ste'CURVE_NAME = 'steering_assist'(COMMENTS){comment_line}'Example of a steering assist spline'


136

The parameter steering_assist then refers to a sub-block of information within your property file. When your product reads the property file, it populates the general spline with the data. The following shows the data block for the steering_assist spline:

$----------------------------------------------------STEERING_ASSIST[STEERING_ASSIST]piston_area <area> = 490.87(XY_DATA){tbar_deflection <angle> delta_pressure <MPa>}-3.00 -4.00 -2.20 -4.00 -1.80 -3.60 -1.50 -3.00 -1.00 -2.00 -0.50 -1.00 0.00 0.00 0.50 1.00 1.00 2.00 1.50 3.00 1.80 3.60 2.20 4.00 3.00 4.00

This mechanism lets you generate and use both 2D and 3D splines with data stored within your database structure by simply selecting the property file that stores the data and defining the data block.

To create or modify a general spline:

1. From the Build menu, point to General Data Elements, point to Spline, and then select New/Modify.

2. Press F1 and then follow the instructions in the dialog box help for Create/Modify General Spline.

3. Select OK.

General VariablesThe general variable is an Adams/Solver (data element) variable whose real value is stored in a property file data block. The property file must be in the neutral file format of your template-based product. When your template-based product reads the property files, it updates the general variable entity with the appropriate real value stored in the property file. The data block and attribute names in the Create General Variable dialog box identify the data that is being accessed from the property file.

The mechanism described for the general parameter is equally applicable to the general variable.

If your template-based product does not find the specified data blocks in the selected property file, then it issues a warning and the general variable function retains its default value (0.0).

To create or modify a general variable:

1. From the Build menu, point to General Data Elements, point to Variable, and then select New/Modify.

137Working with ComponentsData Elements, Requests and Variables

2. Press F1 and then follow the instructions in the dialog box help for Create/Modify General Variable.

3. Select OK.

Parameter VariablesYou can use parameter variables to parameterize various elements and entities in your template-based product. There are three types of parameter variables:

• String - Does not contain units information, only a string value.

• Integer - Does not contain units information, only an integer value.

• Real - Can contain both a real value and a units specification.

Regardless of the parameter variable type, you can choose to hide the parameter variable from the standard user. When you designate a parameter variable as hidden, the standard user will not be able to access it using the Modify Parameter Variable dialog box in the Standard Interface.

RequestsYou can use the Create Request dialog box to create a request statement and auxiliary variables used by your template-based product. A request statement indicates a set of data you want Adams/Solver to output in the request file (.req). You can explicitly do the following:

• Output a set of displacements, velocities, accelerations, or forces with respect to existing markers in your template. Learn about markers.

• Define the generic request function

• Use the user-written subroutine REQSUB to define nonstandard output. For information on user-written subroutines, see Adams/Solver Subroutines.

For information on creating requests, see the Adams/View online help.

Data ElementsData elements include arrays, curves, splines, matrices, and strings.

For information on data elements, see the Adams/View online help

System ElementsSystem elements let you create general differential and/or algebraic equations.

For information on system elements, see the Adams/View online help





138

Working with Templates

Adams/CarTemplate Basics

140

Template BasicsYour template-based product's library includes a variety of templates. Templates define the topology, major role, and default parameters for subsystems. This tab includes template information that is specific to your product.

For general template information, as well as information about the other files that make up model architecture, see Building Models.

Conventions in Template DescriptionsFor each template description, we provide the following:

• Overview - A brief description of the template.

• Template Name - The file name containing the template.

• Major Role - The major role of the template.

• Application - The types of analyses in which you can use the template.

• Description - A complete description of the template and its use.

• Limitations - Limitations of the template design that you should be aware of.

• Files Referenced - The property or MNF files that the template uses to define such entities as bushings, springs, and flexible bodies.

• Topology - How the different entities of the template connect and how forces or torques are transferred from one entity to another.

• Parameter Variables - The parameter variables that store key information in the template. For example, in templates, parameter variables often store angles for a suspension or the orientation of axes.

• Communicators - Communicators used in the template.

• Notes - Miscellaneous information about the template.

When we refer to communicator and parameter names, we often use the notation [lr] to indicate that there is both a left and right communicator or parameter of the specified name.

About Designing TemplatesAdams/Car templates are parameterized models in which you define the topology of vehicle components. Building a template means defining parts, how they connect to each other, and how the template communicates information to other templates and the test rig.

At the template level, it is not crucial that you correctly define the parts, assign force characteristics, and assign mass properties, because you can modify these values at the subsystem level. It is very important, however, to correctly define part connectivity and exchange of information, because you cannot modify them at the subsystem level.

141Working with TemplatesTemplate Basics

When building templates, keep in mind the assembly process. That is, make sure that your templates can communicate to each other and can communicate to the test rigs you specify. In Adams/Car, communicators define how models communicate.

Template UpdatesThe 2005 Driving Machine employs vehicle controllers developed by MSC.Software, commonly known as Machine Control, which replaces DriverLite functionality, and Adams/SmartDriver. You must update Adams/Car 2003 powertrain and body templates to make the compatible with the enhanced Driving Machine in Adams/Car.

To better control speed and path, the 2005 Driving Machine needs additional information about the vehicle. In particular, the speed controller uses a feed-forward function to ensure quick and accurate response. However, this requires information about the available engine brake torque, engine drive torque, brake torque, and aerodynamic drag. You supply this information by creating new output communicators in your templates powertrain and body/aerodynamic templates. In addition, you must also enter vehicle parameter data, such as overall steering ratio that is stored in the assembly file.

Powertrain Template Update

You should update powertrain templates by creating new output communicators to match the following input communicators in the testrig used by the Driving Machine:

• testrig.cis_max_engine_driving_torque

• testrig.cis_max_engine_braking_torque

• testrig.cis_engine_speed

• testrig.cis_engine_map

Maximum engine driving and braking torques

For closed-loop machine control, the maximum engine driving and braking torques must be communicated to the Driving Machine. The machine control uses these values in its feed forward computations when determining the needed throttle and brake inputs to achieve a target longitudinal acceleration. The Driving Machine expects powertrain templates to provide these torques as Solver Variables. The torques should depend on the engine speed. You must add two output communicators to your powertrain template and the corresponding entities that are output. The entities are data element solver variables that compute the maximum driving and maximum braking torques the powertrain subsystem produces at the current engine speed. Note that without this information machine control of the vehicle speed and/or longitudinal acceleration will be unreliable.

In the powertrain.tpl and .powertrain_lt.tpl template files distributed in the shared car database, there are Adams/Solver VARIABLEs with functions computing the maximum powertrain torque (fully open throttle) and maximum powertrain brake torque (closed throttle):

AKISPL(MAX(0,VARVAL(engine_speed)/ucf_angle_to_radians),1,gss_engine_torque)


142

AKISPL(MAX(0,VARVAL(engine_speed)/ucf_angle_to_radians),0,gss_engine_torque)

These functions interpolate the 3D engine map spline at the current engine speed for at full throttle (max engine driving torque) and closed (0) throttle position (max engine braking torque).

The output communicators you create to output these Adams/Solver VARIABLE are:

Name: engine_driving_torque

Matching Name: engine_maximum_driving_torque

Entity Type: solver_variable

Minor Role: inherit

Entity: engine_driving_torque

Name: engine_braking_torque

Matching Name: engine_maximum_braking_torque


Minor Role: inherit

Entity: engine_braking_torque

Engine Map

If your powertrain contains an engine map spline (torque vs. engine speed and throttle position), you can output the spline to the Driving Machine via an output communicator to achieve better control of speed and longitudinal acceleration. However, the engine map is optional. Define the engine_map output communicator as:

Name: engine_map

Matching Name: engine_map

Entity Type: spline

Minor Role: inherit

Entity: gss_engine_torque

In the templates powertrain.tpl and powertrain_lt.tpl distributed in the shared car database, the engine_map output communicators reference the gss_engine_torque spline entity. In your own templates, choose the appropriate spline.

The engine speed is a solver variable outputting the engine speed in radians/s.

Engine speed

In the case of a closed-loop controller on the vehicle forward velocity, you must define an output communicator in your powertrain template, as follows:

Name: engine_speed

Matching Name: engine_speed

143Working with TemplatesTemplate Basics


Minor Role: inherit

Entity: engine_speed

The solver variable, engine_speed, represents the engine rotational velocity expressed in angular/time units [rad/second]. In the powertrain template distributed in the shared car database , engine_speed is defined as MAX(0,DIF(._powertrain.engine_omega)).

The __mdi_sdi_testrig references the output communicator you define and SmartDriver uses that communicator in the smart_driver_controller_inputs_array. The SmartDriver controller input array references various entities used to sense certain vehicle states. Adding the engine_speed communicator enables the longitudinal controller so you can perform a constant-speed maneuver or any other type of closed-loop machine control.

Aero Drag Force

If your vehicle model includes aerodynamic forces, then the drag force affects the longitudinal dynamics of the vehicle. The feed-forward speed controller can account for the drag force when predicting the throttle position needed to follow velocity or acceleration profile, if you create an output communicator that passes the aerodynamic drag force to the __mdi_sdi_testrig. If your vehicle model does not include aerodynamic forces, then you do not need to create an output communicator for the drag force.

The chassis template delivered in the shared car database, for example, has an aerodynamic force modeled using a GFORCE. The GFORCE’s drag (longitudinal) force component is measured in a solver VARIABLE named aero_drag_force with this function expression:

GFORCE(aero_forces,0,4,aero_drag_reference_marker)

Then, the aerodynamic drag is output to the __mdi_sdi_testrig using output communicator of type solver variable:

Name: aero_drag_force

Matching Name: aero_drag_force


Minor Role: inherit

Entity: aero_drag_force

Other Vehicle Parameters

Some sets of quantities that are used by the Adams/SmartDriver lateral and longitudinal controllers cannot be easily inferred from the vehicle model. These quantities are defined in the test rig as parameter variables and are easily accessible. To modify vehicle parameters, display the Set Full-Vehicle Parameters dialog. From the Simulate menu, point to Full Vehicle Analysis, and then select Set Full-Vehicle Parameters.

In the resulting dialog box, you can set the following ratios that affect the lateral dynamics of the vehicle, providing Adams/SmartDriver information about the characteristics of the steering system. Bad values


144

almost certainly guarantee solver failure in closed-loop events or, if successful, the vehicle will most certainly be off course.

• Steering Ratio - Dimensionless ratio between the steering wheel angle and the road wheel angle. You can obtain this value by running a steering analysis on the front suspension and steering assembly.

• Steering Rack Ratio - Ratio (angle/length) between the steering hand wheel and the rack displacement expressed in S.I. units. This parameter influences the response of the controller only when driving by force/displacement.

The following parameters help Adams/SmartDriver in predicting and calculating the brake signal:

• Max. Front/Rear Brake Torque - Maximum torque, expressed in model units, representing the torque generated for each front/rear brake in condition of maximum brake demand, also expressed in model units.

• Brake Bias - Front to rear dimensionless ratio. It can be computed as max_front_brake_torque / (max_front_brake_torque + max_rear_brake_torque).

These parameters are saved to the assembly file, as well as to the test rig in session.

Creating Topology for Your TemplatesTopology in Adams/Car consists of creating elements, such as hardpoints, parts, attachments, and parameters that define subsystems, as explained next:

• Creating hardpoints - You first create hardpoints. Hardpoints are the Adams/Car elements that define all key locations in your model. They are the most elementary building blocks that you can use to parameterize locations and orientations for higher-level entities. Hardpoint locations define most parts and attachments. Hardpoints are only defined by their coordinate locations.

• Creating parts - Once you’ve defined hardpoints, you create parts and define them using the hardpoints that you created. In this tutorial, you create two types of parts: General Parts, such as control arm and wheel carrier, and Mount Parts.

• Creating attachments - Finally, you create the attachments, such as joints and bushings, and parameters which tell Adams/Car how the parts react in relation to one another. You can define attachments for the compliant and kinematic analysis modes. The compliant mode uses bushings, while the kinematic mode uses joints.

Before you begin to build a template, you must decide what elements are most appropriate for your model. You must also decide which geometries seem most applicable to each part or whether you want any geometry at all. Once you’ve decided, you create a template and create the basic topology for it.

145Working with TemplatesWorking with Communicators

Working with CommunicatorsYou use communicators to exchange of information between subsystems, templates, and the test rig in your assembly.

This topic includes information for Adams/Car communicators. For general information on communicators, see Building Models.

Learn more about working with communicators in Adams/Car:

• Communicators in the Suspension Test Rig

• Communicators in the SDI Test Rig

• Matching Communicators with Test Rigs

Communicators in the Suspension Test RigThe following tables describe the input and output communicators in the suspension test rig (.__MDI_SUSPENSION_TESTRIG). In the tables, the notation:

• [lr] indicates that there is both a left and right communicator of the specified name, as in ci[lr]_camber_angle.

• s indicates a single communicator, as in cis_steering_rack_joint.

Communicators in the Suspension Test Rig

The communicator:Belongs to the

class:

From minor role: Receives:

ci[lr]_camber_angle parameter_real any Camber angle value from the suspension subsystem. Sets the correct orientation of the test rig wheels.

ci[lr]_diff_tripot location any Location of the differential.

ci[lr]_toe_angle parameter_real any Toe angle value from the suspension subsystem. Sets the correct orientation of the test rig wheels.

ci[lr]_suspension_mount mount any Part to which the test rig wheels can attach.

ci[lr]_suspension_upright mount any Upright part from suspension subsystem.

ci[lr]_jack_frame mount any Not matched (fixed to ground).

ci[lr]_wheel_center location any Location of the wheel center from the suspension subsystem. Test rig wheels attach to the suspension at that location.

Adams/CarWorking with Communicators

146

Output Communicators in Suspension Test Rig

Communicators in the SDI Test RigThe following tables describe the input and output communicators in the SDI test rig (.__MDI_SDI_TESTRIG). In the tables, the notation [lr] indicates that there is both a left and right communicator of the specified name.

cis_driveline_active parameter_integer any Integer value stored in the suspension template/subsystem that indicates the activity of the drivetrain.

cis_powertrain_to_body mount any Part to which differential outputs are constrained.

cis_leaf_adjustment_steps parameter_integer any Integer value stored in the leaf spring template (currently not available).

cis_steering_rack_joint joint_for_motion any Steering-rack translational joint from the steering subsystem.

cis_steering_wheel_joint joint_for_motion any Steering-wheel revolute joint from the steering subsystem.

cis_suspension_parameters_ARRAY array any Array used in the suspension characteristic calculations; comes from the suspension subsystems.


class:


The communicator:Belongs to the class:

From minor role: Outputs:

cos_leaf_adjustment_multiplier array any Leaf Spring toolkit. It is currently not supported in the standard product.

cos_characteristics_input_ARRAY array any Suspension, vehicle, and test-rig parameters array IDs used by suspension characteristics calculations routines.

co[l,r]_tripot_to_differential mount any Outputs the ge[lr]_diff_output parts.

cos_tire_forces_array_left array any Outputs array of Adams IDs used by the conceptual suspension module.

cos_tire_forces_array_right array any Outputs array of Adams IDs used by the conceptual suspension module.


Input Communicators in SDI Test Rig


class:


cis_body_subsystem mount inherit Output from the body subsystem. It indicates the part that represents the body.

cis_chassis_path_reference marker any Marker from the body subsystem. It is used to measure path, roll, and sideslip error in a constant radius cornering maneuver.

cis_driver_reference marker any Marker from the body subsystem. It is used in Adams/SmartDriver simulations.

cis_engine_rpm solver_variable any Adams/Solver variable for engine revolute speed, in rotations per minute, from the powertrain subsystem.

cis_engine_speed solver_variable any Adams/Solver variable for engine revolute speed, in radians per second, from the powertrain subsystem.

cis_measure_for_distance marker any Marker used to measure the distance traveled in the forward direction of the vehicle, from the body subsystem.

cis_diff_ratio parameter_real any Real parameter variable for final drive ratio, from the powertrain subsystem.

cis_steering_rack_joint joint_for_motion front Steering-rack translational joint from the steering subsystem.

cis_steering_wheel_joint joint_for_motion front Steering-wheel revolute joint from the steering subsystem.

cis_max_brake_value parameter_real any Output from brake subsystem (maximum brake signal value).

cis_max_engine_speed parameter_real any Output from powertrain subsystem (maximum engine rpm value).

cis_max_gears parameter_integer

any Output from powertrain (maximum number of allowed gears).

cis_max_rack_displacement parameter_real any Output displacement limits from steering subsystem. Used by the Standard Driver Interface.

cis_max_rack_force parameter_real any Output force limits from steering subsystem. Used by the Standard Driver Interface.

cis_max_steering_angle parameter_real any Output angle limits from steering subsystem. Used by the Standard Driver Interface.


148

Output Communicators in SDI Test Rig

cis_max_steering_torque parameter_real any Output from steering subsystem.

cis_max_throttle parameter_real any Output from powertrain (maximum value of throttle signal).

cis_min_engine_speed parameter_real any Output from powertrain subsystem (minimum engine rpm value, used for shifting strategy).

cis_rotation_diff diff any Output from powertrain (it is a differential equation used to measure crankshaft acceleration; its integral is used for engine rpm).

cis_transmission_spline spline any Spline for transmission gears (output from powertrain: reduction ratios for every gear).

cis_transmission_input_omega solver_variable any The transmission input engine variable from the powertrain template.

cis_clutch_diff diff any Clutch slip differential equation from the powertrain template.

cis_clutch_displacement_ic solver_variable any The clutch initial displacement (engine crankshaft torque at static equilibrium) from the powertrain template.

ci[lr]_front_suspension_mount mount front The hub parts (wheel carriers) from suspension templates (front and rear)

ci[lr]_rear_suspension_mount mount rear The hub parts (wheel carriers) from suspension templates (front and rear)


class:



class:


cos_brake_demand solver_variable any Brake demand to the brake subsystem.

cos_clutch_demand solver_variable any Clutch demand to the powertrain subsystem.

cos_desired_velocity solver_variable any Desired velocity Adams/Solver variable. Other subsystems can reference it.

cos_initial_engine_rpm parameter_real any Initial engine RPM real variable to the powertrain subsystem.

cos_throttle_demand solver_variable any Throttle demand to the powertrain subsystem.


Matching Communicators with Test RigsWhen you create a template, you must meet the following conditions to ensure that an analysis will work with your new template:

• The template must be compatible with other templates and with the test rigs, for example, the .__MDI_SUSPENSION_TESTRIG. The template must also contain the proper output communicators.

• If the template is a suspension template (for example, its major role is suspension), the template must contain a suspension parameters array. The suspension parameters array identifies to the suspension analysis how the steer axis should be calculated and whether the suspension is independent or dependent.

For example, for a suspension template to be compatible with the suspension test rig, the suspension template must contain either the mount or the upright output communicators. In the following table, the notation [lr] indicates that there is both a left and right communicator of the specified name.

Output Communicators in Suspension Templates

The co[lr]_suspension_mount output communicators publish the parts to which the test rig wheels should mount. As you create these communicators, ensure that you set their minor role to inherit. By setting the minor role to inherit, the communicator takes its minor role from the minor role of the subsystems that use your suspension template.

cos_transmission_demand solver_variable any Transmission (gear) demand to the powertrain subsystem.

cos_sse_diff1 diff any Differential equation computed during quasi-static prephase, used to control the vehicle longitudinal dynamics.

cos_std_tire_ref location any X,Y,Z location of standard tire reference marker (positioned appropriately at the correct height, including 2% of road penetration).


class:


The communicator: Belongs to the class: From minor role: Receives:

co[lr]_suspension_mount mount inherit suspension_mount

co[lr]_suspension_upright mount inherit suspension_upright

co[lr]_wheel_center location inherit wheel_center

co[lr]_toe_angle parameter_real inherit toe_angle

co[lr]_camber_angle parameter_real inherit camber_angle


150

The co[lr]_wheel_center output communicators publish the location of the wheel centers to the test rig so the test rig can locate itself relative to the suspension. As you create these types of communicators, make sure that you also leave their minor role set to inherit.

The toe and camber communicators (co[lr]_toe_angle and co[lr]_camber_angle) publish, to the test rig, the toe and camber angles set in the suspension so the test rig can orient the wheels correctly.

151Working with TemplatesTemplates

Templates

Disc-Brake System

Overview

The disc-brake system template represents a device that applies resistance to the motion of a vehicle.

Figure 1 Disc-Brake System

Template name

_brake_system_4Wdisk

Major role

Brake.

Application

Full-vehicle Analysis to simulate the effect of braking on the dynamics of the vehicle.

Description

The disc-brake system template represents a simple model of a brake system. It applies a rotational torque between the caliper and the rotor.

Adams/CarTemplates

152

Files referenced

None.

Topology

The caliper part is mounted to the suspension upright, while the rotor is mounted to the wheel. A rotational SFORCE is applied between the two parts.

Parameters

The toe and camber values that the suspension subsystem publishes define the spin axis orientation. In addition, the braking torque is expressed as a function of a number of parameters.

The following table lists the parameters in the template.

Limitations

The disc-brake template is a simple model of a brake system. It does not model the complex interaction between the rotor and caliper.

Communicators

Mount parts provide the connectivity between the template and suspension subsystems. Input Communicators receive information about the toe and camber suspension orientation and the wheel-center location. Input to the brake system is brake demand.

The parameter: Takes the value: Its units are:

front_brake_bias Real No units

front_brake_mu Real No units

front_effective_piston_radius Real mm

front_piston_area Real mm2

front_rotor_hub_wheel_offset Real mm

front_rotor_hub_width Real mm

front_rotor_width Real mm

max_brake_value Real No units

rear_brake_mu Real No units

rear_effective_piston_radius Real mm

rear_piston_area Real mm2

rear_rotor_hub_wheel_offset Real mm

rear_rotor_hub_width Real mm

rear_rotor_width Real mm


The following table lists the communicators in the template.

The communicator: Belongs to the class: Has the role:

ci[lr]_front_camber_angle parameter_real front

ci[lr]_front_rotor_to_wheel mount front

ci[lr]_front_toe_angle parameter_real front

ci[lr]_front_wheel_center location front

ci[lr]_front_suspension_ upright mount front

ci[lr]_rear_rotor_ro_wheel mount rear

ci[lr]_rear_suspension_ upright mount rear

ci[lr]_rear_toe_angle parameter_real rear

ci[lr]_rear_camber_angle parameter_real rear

ci[lr]_rear_wheel_center location rear

cis_brake_demand solver_variable any

cos_max_brake_value parameter_real inherit

Adams/CarTemplates

154

Notes: The torque on the rotor depends on a number of parameters. The front right torque function is:

T = 2 x PistonArea x BrakeLinePressure x µ x EffectivePistonRadius x STEP

where:

• BrakeLinePressure is calculated as follows:

BrakeLinePressure = BrakeBias * BrakeDemand * 0.1where:

• BrakeBias defines the front and rear proportioning of the brake line pressure. Note that although the term is constant, in reality, simple hydraulic systems allow dynamic front and rear proportioning of the brake pressure depending on a number of factors, including longitudinal slip angle of the tires and dynamic load transfer.

• BrakeDemand is the force on the pedal (N) as it is output from the analysis.

• 0.1 is a conversion factor that converts into pressure the force applied on the pedal.

• STEP is the function of the rotation of the rotor to wheel and suspension upright markers. The function prevents backward spinning of the wheels. STEP is a simple function that measures the WZ rotation of the marker on the rotor with respect to the marker on the upright and reverses the sign of the applied torque if the wheel is spinning backward.


Double-Wishbone Suspension

Overview

A double-wishbone suspension is one of the most common suspension designs. It uses two lateral control arms to hold the wheel carrier and control its movements.

Figure 2 Double-Wishbone Suspension

Template name

_double_wishbone

Major role

Suspension

Application

Suspension and full-vehicle assemblies

Adams/CarTemplates

156

Description

The double-wishbone template represents the most common design for doublewishbone suspensions. You can use the template as a front steerable suspension or as a rear non-steerable suspension.

You can set subsystems based on this template to kinematic or compliant mode. In kinematic mode, Adams/Car replaces the bushings that connect the control arms to the body mount part with a corresponding purely kinematic constraint. Adams/Car also does this for the top mount and lower strut mount.

You can deactivate the subframe part, as well as the halfshafts. A spring acts between the upper mount part and the lower strut. A bumpstop acts between the upper and lower strut parts.

Files referenced

Bushings, springs, dampers, and bumpstops property files

Topology

The lower wishbone connects to a subframe or to the mount if you've deactivated the subframe. The upper wishbone connects to the body mount part. A spherical joint constrains the upright part to the upper and lower arms.

A spherical joint also connects the tie rods to the uprights. Tie rods attach to mount parts through convel joints. Convel joints also connect the tripots to the drive shafts. A static rotation control actuator locks the rotational degree of freedom of the hub during quasi-static analyses.

The joint: Connects the part: To the part:

jklrev_lca gel_lower_control_arm ges_subframe

jolsph_lca_balljoint gel_upright gel_lower_control_arm

jolsph_tierod_outer gel_tierod gel_upright

jolcon_tierod_inner gel_tierod mtl_tierod_to_steering

josfix_subframe_rigid ges_subframe mts_subframe_to_body

jklhoo_top_mount_kinematic gel_upper_strut mtl_strut_to_body

jolsph_uca_balljoint gel_upper_control_arm gel_upright

jolcyl_lwr_upr_strut gel_lower_strut gel_upper_strut

jklrev_uca gel_upper_control_arm mtl_uca_to_body

jklhoo_lwr_strut_kinematic gel_lower_strut gel_lower_control_arm

joltra_tripot_to_differential gel_tripot mtl_tripot_to_differential

jolcon_drive_sft_int_jt gel_tripot gel_drive_shaft

jolcon_drive_sft_otr gel_drive_shaft gel_spindle


Parameters

Toe and camber variables define wheel spin axis, spindle part, and spindle geometry. The following table lists the parameters in the template.


phs_driveline_active Integer No units

phs_kinematic_flag Integer No units

pvs_subframe_active Integer No units

pv[lr]_toe_angle Real Degrees

pv[lr]_camber_angle Real Degrees

pv[lr]_drive_shaft_offset Real mm

Adams/CarTemplates

158

Communicators

Mount parts provide connectivity from the template to body subsystems and the differential. Output Communicators publish toe, camber, steer axis, and wheel-center location information to the appropriate subsystems and the test rig. The following table lists the input and output communicators.


ci[lr]_ARB_pickup location inherit

ci[lr]_strut_to_body mount inherit

ci[lr]_tierod_to_steering mount inherit

ci[lr]_tripot_to_differential mount inherit

ci[lr]_uca_to_body mount inherit

cis_subframe_to_body mount inherit

co[lr]_arb_bushing_mount mount inherit

co[lr]_camber_angle parameter_real inherit

co[lr]_droplink_to_ suspension mount inherit

co[lr]_suspension_mount mount inherit

co[lr]_suspension_upright mount inherit

co[lr]_toe_angle parameter_real inherit

co[lr]_tripot_to_differential location inherit

co[lr]_wheel_center location inherit

cos_driveline_active parameter_integer inherit

cos_engine_to_subframe mount inherit

cos_rack_housing_to_suspension_subframe mount inherit

cos_suspension_parameters_ARRAY array inherit

Note: The integer parameter variables allow you to activate and deactivate the subframe part and the driveshafts. The kinematic flag variable toggles between kinematic and compliant mode.


Flexible LCA Double-Wishbone Suspension

Overview

The flexible LCA double-wishbone suspension template is similar to the standard Double-Wishbone Suspension. In the flexible template, however, a flexible representation replaces the rigid body lower control arms.

Figure 3 Flexible LCA Double-Wishbone Suspension

Template name

_double_wishbone_flex

Major role

Suspension

Application


Description

Flexible bodies replace the left and right rigid lower control arms.

Adams/CarTemplates

160

MNF files referenced

LCA_left_shl.mnf and LCA_right_shl.mnf. In addition, because of the way the node IDs are numbered, you can swap the default modal neutral files with LCA_left_tra.mnf and LCA_right_tra.mnf.

Topology

In addition to the general topology described for the Double-Wishbone Suspension, this template uses interface parts to connect the flexible bodies to the rest of the suspension. Node IDs define the location of interface parts.

Parameters, Communicators & Notes

Refer to the Double-Wishbone Suspension.

ISO Road Course

Overview

The ISO road course template represents a closed circuit with an ISO lane-change section.

Figure 4 ISO Road Course

Template name

_ISO_road_course


Major role

Environment

Application

With the optional Adams/Driver module

Description

The ISO road course template consists of shell elements and frustums, and represents a closed circuit with an ISO lane-change section.

Files referenced

Geometry elements (shells) reference shell files stored in the Adams/Car shared database in the shell_graphics.tbl directory. The shell files are Iso_road_inr.shl, Iso_road_otr.shl, and Iso_road_c.shl.

Topology

All the graphic elements are created on the ground part.

Parameters

Contains no parametric information.

Communicators

Contains no communicators.

MacPherson Suspension

Overview

The MacPherson suspension design in this template is similar to the SLA geometry, and is probably the most often used suspension for passenger cars in the world. It uses a telescopic strut incorporating a

Note: The corresponding Adams/Driver representation of this course is available as a trace on the x-y plane and lane width in the driver_roads.tbl directory. The file is called ISO_road_course.drd. You can use the file to run full-vehicle analyses with Adams/Driver. Including the ISO road course template in your full-vehicle assembly adds a graphical representation of the circuit.

Adams/CarTemplates

162

damper element. The upper end is fixed to the body and the lower end is located by linkages. The MacPherson design provides advantages in packaging, and it is generally used for front-wheel-drive cars.

Figure 5 MacPherson Suspension

Template name

_macpherson

Major role

Suspension

Application


Description

The MacPherson suspension template represents the most common design for MacPherson suspensions. You can use the template as a front steerable suspension or as a rear non-steerable suspension.

You can set the subsystems based on this template to kinematic or compliant mode. In kinematic mode, Adams/Car replaces the bushings with the corresponding kinematic constraints. The bushings connect


the control arm and the damper strut to the body mount parts. You can also activate or deactivate driveshafts.

A spring acts between the upper strut part and the lower strut. Bumpstops and reboundstops are also present.

Files referenced

Bushings, springs, dampers, bumpstops, and reboundstops property files

Topology

The MacPherson suspension template represents a standard design employing a one-piece lower control arm (also known as A-arm) and a subframe. The upright to which the wheel mounts is located by the lower control arm, the tie rod, and the strut. The lower control arm regulates the fore-aft and lateral motions of the upright. The tie rod controls steering rotation of the upright, and the strut controls the vertical motion of the upright and the side and front view rotations, as well. A static rotation control actuator locks the rotational degree of freedom of the hub during quasi-static analyses.

The following table lists the topological information of the left side of the MacPherson suspension.


jklrev_lca gel_lower_control_arm ges_subframe

jolsph_lca_balljoint gel_upright gel_lower_control_arm

jolcyl_strut gel_upright gel_upper_strut

jolsph_tierod_outer gel_tierod gel_upright

jolcon_tierod_inner gel_tierod mtl_tierod_to_steering

jksfix_subframe_rigid ges_subframe mts_subframe_to_body

jklhoo_top_mount_kinematic gel_upper_strut mtl_strut_to_body




jolrev_spindle_upright gel_spindle gel_upright

Adams/CarTemplates

164

Parameters

Toe and camber variables in the template define the wheel spin axis, spindle part, and spindle geometry. The following table lists the parameters in the templates.








Communicators

Mount parts provide the connectivity from the template to the body subsystems and differential. Output communicators publish toe, camber, steer axis, and wheel-center location information to the appropriate subsystems and test rig. The following table lists the input and output communicators in the template.


ci[lr]_ARB_pickup location inherit


ci[lr]_tierod_to_steering mount inherit



co[lr]_arb_bushing_mount mount inherit


co[lr]_droplink_to_ suspension mount inherit







cos_rack_housing_to_ suspension_subframe mount inherit


Note: The integer parameter variables let you activate and deactivate the driveshafts. The kinematic flag variable toggles between kinematic and compliant mode replacing the joints with the corresponding elastic elements. For example, Adams/Car replaces the revolute joints that connect the lower control arms to the subframe with bushings

Adams/CarTemplates

166

Multi-Link Suspension

Overview

The multi-link suspension represents an independent suspension model for use as a rear suspension.

Figure 6 Multi-Link Suspension

Template name

_multi_link

Major role

Suspension

Application


Description

The multi-link suspension template represents a common rear independent suspension design. It includes a subframe (represented by the outline graphics) that is connected to the upper arm, to the lateral links, and to the track rod. The suspension is nonsteerable and intended to be used as a rear suspension only.


Files referenced

Springs, dampers, and bushings property files

Topology

Spherical joints, which are active in kinematic mode, connect the uprights to links. Bushings connect the trailing links to the mount parts. Springs and dampers act between the trailing links and the body. A static rotation control actuator locks the rotational degree of freedom of the hub during quasi-static analyses.

The following table provides a topological map of the template.

Parameters

Toe and camber variables in the template define the wheel spin axis, spindle part, and spindle geometry. The following table lists the parameters in the templates.


jklsph_hub_tl gel_Upright gel_Trailing_Link

jklhoo_trailing_link_body gel_Trailing_Link mtl_trailing_link_body

jklrev_ula_sbf gel_upper ges_Subframe

joltra_dpr_upr_dpr_lwr gel_Damper_Upper gel_Damper_Lower

jklsph_dpr_lwr_tl gel_Damper_Lower gel_Trailing_Link

jklhoo_dpr_spring_seat_upper gel_Damper_Upper mtl_Spring_Seat_Upper

jksfix_sbf_body ges_Subframe mtl_body_sbf_front

jklsph_hub_ll gel_Upright gel_lateral

jklsph_hub_tr gel_Upright gel_Track_Rod

jklhoo_sbf_ll ges_Subframe gel_lateral

jklhoo_sbf_tr ges_Subframe gel_Track_Rod

jklsph_hub_ula gel_Upright gel_upper




jolrev_spindle_upright gel_spindle gel_Upright




pvs_subframe_active Integer No units

Adams/CarTemplates

168

Communicators



pv[lr]_camber_angle Real mm



ci[lr]_body_sbf_front mount inherit

ci[lr]_body_sbf_rear mount inherit

ci[lr]_Spring_Seat_Upper mount inherit

ci[lr]_trailing_link_body mount inherit








cos_suspension_ parameters_ARRAY array inherit


Note: The integer parameter variables let you activate and deactivate the subframe part and the driveshafts. The kinematic flag variable toggles between kinematic and compliant mode.


Parallel-Link Steering System

Overview

The parallel-link steering system template is essentially a four-bar mechanism consisting of a pitman arm, center link, and idler arm.

Figure 7 Parallel-Link Steering

Template name

_parallel_link_steering

Major role

Steering

Application


Description

A recirculating ball steering gear transmits motion from the steering wheel to the pitman arm. The pitman arm rotates to impart motion to the center link and idler arm. The translation of the center link pulls and pushes the tie rods to steer the wheels.

Adams/CarTemplates

170

Files referenced

Steering assist and torsion bar deflection property file. The default property file is mdi_steer_assis.ste, stored in the steer_assist.tbl directory of the shared Adams/Car database.

Topology

The recirculating ball steering gear consists of three major parts:

• Ball screw

• Rack

• Sector

The steering wheel rotates the steering input shaft. A torsion bar attaches the steering input shaft to a ball screw. The ball screw imparts translational motion to the steering gear through a coupler. The steering gear, in turns, rotates the sector through a coupler, which is connected directly to the pitman arm shaft.

The following table maps the topology of the template.


joshoo_column_intermediate ges_steering_column ges_intermediate_shaft

joshoo_intermediate_shaftinput ges_intermediate_shaft ges_input_shaft

josrev_steering_wheel ges_steering_wheel ges_column_housing

joscyl_steering_column ges_steering_column ges_column_housing

josfix_column_housing_to_housing_mount

ges_column_housing mts_steering_column_to_body

jolsph_centerlink_arm ges_center_link gel_arm

jolrev_pitman_arm_steering_gear gel_arm swl_steering_gear_mount

josrev_ball_screw_steering_gear ges_ball_screw swl_steering_gear_mount

josrev_input_shaft_steering_gear ges_input_shaft swl_steering_gear_mount

jostra_rack_steering_gear ges_rack swl_steering_gear_mount

josfix_steering_gear_housing ges_steering_gear_housing swl_steering_gear_mount

josper_centerlink_pitman_arm ges_center_link gel_arm

vfo_steering_assist ges_rack swl_steering_gear_mount

gksred_ball_screw_input_shaft_lock josrev_ball_screw_steering_gear

josrev_input_shaft_steering_ gear

grsred_steering_wheel_column_lock josrev_steering_wheel joscyl_steering_column


Parameters

A parameter variable switches between kinematic and compliant mode, effectively defining the status of the ball screw input shaft lock reduction gear.

Communicators


grsred_ball_screw_rack josrev_ball_screw_steering_gear

jostra_rack_steering_gear

grsred_pitman_arm_rack jolrev_pitman_arm_steering_gear



ci[lr]_steering_gear_to_body mount inherit

ci[lr]_steering_gear_to_suspension_subframe mount inherit

cis_steering_column_to_ body mount inherit

co[lr]_tierod_to_steering mount front

cos_max_rack_ displacement parameter_real inherit

cos_max_rack_force parameter_real inherit

cos_max_steering_angle parameter_real inherit

cos_max_steering_torque parameter_real inherit

cos_steering_rack_joint joint_for_motion inherit

cos_steering_wheel_joint joint_for_motion inherit


Note: The parallel-link steering template contains general spline elements. The general spline element gss_torsion_bar spline provides torque as a function of the angular deflection of the input shaft relative to the ball screw. A switch part is also present. It allows you to explore two different topological solutions. You can rigidly connect the steering gear to the body or to the suspension_subframe part.

Adams/CarTemplates

172

Pitman Arm Steering System

Overview

The pitman arm steering system template is a simple steering system derived from a parallel-link design. It is commonly used in trucks. It consists of a three-bar mechanism: pitman arm, draglink, and tie rod.

Figure 8 Pitman Arm Steering System

Template name

_pitman_arm

Major role

Steering

Application


Description

A recirculating ball steering gear transmits motion from the steering wheel to the pitman arm. The pitman arm rotates to impart motion to the draglink. The draglink pulls and pushes the tie rod and steers the wheels.


Files referenced

The point torque actuator references the torsion_bar datablock in the mdi_steering.ste property file, stored in the Adams/Car shared database, under the steer_assists.tbl table or directory.

Topology

The recirculating ball steering gear consists of three major parts:

• Ball screw

• Rack

• Sector

The steering wheel rotates the steering input shaft. The steering input shaft attaches to the ball screw through a torsion bar, currently locked by a coupler. The ball screw imparts translational motion to the rack, through a coupler. The rack, in turns, rotates the sector through a coupler.

The sector is connected directly to the pitman arm shaft. The pitman arm drags the draglink, which is directly connected to the right wheel, and pulls the tie rod, connected to the left wheel. Spherical joints connect the draglink and tie rod.




joshoo_intermediate_shaft_input

ges_intermediate_shaft ges_input_shaft

josrev_steering_wheel ges_steering_wheel ges_column_housing

joscyl_steering_column ges_steering_column ges_column_housing

josfix_column_housing_to_housing_mount

ges_column_housing mts_steering_column_to_body

josrev_pitman_arm_steering_gear

mts_steering_gear_to_suspension_subframe

ges_idle_arm

jossph_centerlink_arm ges_idle_arm ges_draglink

josrev_input_shaft_steering_gear

ges_input_shaft mts_steering_gear_to_suspension_subframe

josrev_ball_screw_steering_gear

ges_ball_screw mts_steering_gear_to_suspension_subframe

jostra_rack_steering_gear ges_rack mts_steering_gear_to_suspension_subframe

jossph_draglink_to_tierod ges_draglink ges_tierod

Adams/CarTemplates

174

Parameters

A parameter variable switches between kinematic and compliant mode, effectively defining the status of the ball screw input shaft lock reduction gear.

Communicators

The following table lists the Communicators in the template.

grsred_steering_wheel_column_lock

josrev_steering_wheel joscyl_steering_column

gksred_ball_screw_input_shaft_lock

josrev_ball_screw_steering_gear josrev_input_shaft_steering_gear

grsred_pitman_arm_rack josrev_pitman_arm_steering_gear


grsred_ball_screw_rack josrev_ball_screw_steering_gear jostra_rack_steering_gear


ci[lr]_steering_gear_to_suspension_subframe mount inherit


cos_tierod_to_steering mount front

cos_draglink_to_steering joint_for_motion inherit



Note: The pitman arm steering system template does not interface with any of the Adams/Car shared database suspension templates because those suspension templates have tie rods. To correctly assemble the pitman arm steering to a suspension subsystem, you must remove the tie rods from the suspension. The draglink and the tie rod have to be mounted to the left and right upright parts.


Powertrain System

Overview

The Adams/Car shared database includes a powertrain template, powertrain.tpl. The template models an engine, manual transmission, and a limited-slip differential that may be used for a front engine, front-wheel-drive vehicle, or a rear engine, rear-wheel-drive vehicle.

Figure 9 Powertrain

Template name

_powertrain

Major role

Powertrain

Application

Full-vehicle assemblies

Description

The powertrain system template represents an engine, clutch, transmission, and differential:

Adams/CarTemplates

176

• Engine model - Consists of a single part (ges_engine) representing the total mass and inertia of the engine block, clutch housing, and transmission. A general spline element (gss_engine_torque) represents the engine's steady-state torque versus engine speed and throttle position. Before any analysis, gss_engine_torque is updated by reading the engine torque versus engine speed and throttle from a powertrain property file. For example, mdids://acar_shared/powertrains.tbl/V8_240HP_400Nm.pwr. See Torque versus Engine Speed and Throttle Position for this property file.

To allow for larger integration time steps during simulation, the engine crankshaft is not included as a part in the templates. Instead of a rotating crankshaft part, a differential equation (engine_omega) integrates the engine crankshaft's rotational acceleration (Adams/Solver requires one integration time step for each 60 degrees of part rotation). The engine crankshaft's rotational acceleration is the difference between the engine torque and the clutch torque divided by the engine rotational inertia.

• Clutch model - The clutch torque is modulated by the clutch demand, which ranges in value from zero (0) to one (1):

• A clutch demand of zero means that the driver's foot is off the clutch pedal and the clutch is closed.

• A clutch demand of one means that the driver has pushed the clutch pedal completely to the floor and the clutch is open.

You can set the values of clutch demand, for which the clutch is completely closed or open, using the parameter variables pvs_clutch_closed and pvs_clutch_open.

The clutch develops torque only when it is at least partially closed and there is some slip displacement or slip speed between the engine crankshaft and the transmission input shaft. When the clutch is closed, it acts like a torsional spring-damper, except that the maximum clutch torque developed is limited by the clutch capacity, which you can modify (pvs_clutch_capacity).

You also set the clutch's torsional stiffness and damping. When the clutch is partially closed, the clutch stiffness and damping, as well as the clutch capacity (torque), are scaled by the clutch demand.

The clutch slip speed is the difference between the engine crankshaft and the transmission input shaft rotational speeds. When the clutch is closed, the clutch slip displacement is the integral of the clutch slip speed. When the clutch is open, the clutch slip displacement decays to zero with a time constant given by pvs_clutch_tau.

• Transmission model - The transmission model is simple: it applies the gear ratio selected by the gear demand, and has no rotating inertia. The clutch torque is multiplied by the selected gear ratio and applied to the differential input shaft. The differential input shaft speed is likewise multiplied by the same ratio to determine the transmission input shaft speed. You can set the number of gears and the ratio for each gear:

• A gear number of zero (0) represents neutral.

• A gear number of minus one (-1) represents reverse.


• Differential model - The differential model has rotating left and right output shaft parts that connect to half-shafts in suspension subsystems. The differential input shaft speed is the average of the left and right output shaft speeds multiplied by the final drive ratio you enter. Likewise, the transmission output torque is multiplied by the final drive ratio and then split equally between the two output shafts. A reaction torque is applied about the longitudinal axis to the ges_engine part.

The differential model includes a limited slip torque that acts between the left and right differential output shafts. The torque depends on the difference between the output shaft speeds. The limited slip torque-speed characteristic is read from a property file in the differentials.tbl.

Files referenced

The file, V12_engine_map.pwr, stored in the powertrains.tbl directory, defines the engine map. The differential references the MDI_viscous.dif property file, stored in the differentials.tbl directory. The MDI_viscous.dif property file defines the slip torque-speed relationship as a two-dimensional spline.

Topology

The powertrain template contains very simple topological information because it is a functional representation of the powertrain. The only general rigid parts, besides the engine body, are the diff outputs and the revolute joints that connect the rigid bodies to the engine body.

Parameters

The following table lists the powertrain system template parameters.

The parameter: Takes the value: Its units are: Description:

phs_kinematic_flag Integer No units When flag = 1, engine is rigidly mounted to chassis; when flag = 0, engine is mounted on bushings. Set from the Adjust menu.

pvs_clutch_capacity Real Torque Maximum torque clutch can sustain with zero slip speed.

pvs_clutch_close Real No units Value of clutch demand at which clutch is fully closed. Value should be less than pvs_clutch_open and in the range of 0 and 1.

pvs_clutch_damping Real Torsional_damping Clutch damping torque per unit of clutch slip speed.

pvs_clutch_open Real No units Value of clutch demand at which clutch is open.

Adams/CarTemplates

178

Communicators

Mount parts provide the connectivity from the template to the body subsystems. Output communicators publish information, such as engine RPM and transmission spline. The following tables list the input and output communicators in the powertrain system template.

pvs_clutch_stiffness Real Torsional_stiffness Clutch torque developed per unit of clutch slip.

pvs_clutch_tau Real Time Time constant for clutch slip decay when clutch is open.

pvs_ems_gain Real No units Proportional gain used in EMS idle speed control

pvs_ems_max_throttle Real No units Value of throttle demand that corresponds to the maximum capability of the EMS system

pvs_ems_trottle_off Real No units Value of throttle demand at which EMS system engages idle speed control

pvs_engine_idle_speed Real RPM Engine idle speed in RPM.

pvs_engine_inertia Real Inertia Engine rotational inertia. Must be greater than zero.

pvs_engine_rev_limit Real RPM Maximum engine speed in RPM.

pvs_final_drive Real No units Differential input shaft (pinion) to ring gear ratio.

pvs_gear_[1-6] Real No units Transmission input shaft to output shaft ratio for gears 1 through 6.

pvs_graphics_flag Integer No units 1 = include powertrain graphics; 0 = do not include powertrain graphics

pvs_max_gears Integer No units Number of gear ratios in the transmission.

pvs_max_throttle Real No units Value of throttle demand for which throttle is fully open (throttle demand = 0 is throttle closed).

The parameter: Takes the value: Its units are: Description:


Input Communicators

The communicator: Entity class: From minor role: Matching name:

ci[lr]_diff_tripot location inherit tripot_to_differential

ci[lr]_tire_force force inherit tire_force

cis_clutch_demand solver_variable inherit clutch_demand

cis_engine_to_subframe mount inherit engine_to_subframe

cis_initial_engine_rpm parameter_real any initial_engine_rpm

cis_powertrain_to_body mount inherit powertrain_to_body

cis_sse_diff1 diff inherit sse_diff1

cis_throttle_demand solver_variable inherit throttle_demand

cis_transmission_demand solver_variable inherit transmission_demand

Adams/CarTemplates

180

Output Communicators

The communicator: Entity class: To minor role: Matching name:

co[lr]_output_torque force inherit output_torque

co[lr]_tripot_to_differential mount inherit tripot_to_differential

cos_clutch_displacement_ic solver_variable inherit clutch_displacement_ic

cos_default_downshift_rpm parameter_real inherit min_engine_speed

cos_default_upshift_rpm parameter_real inherit max_engine_speed

cos_diff_ratio parameter_real inherit diff_ratio

cos_engine_idle_rpm parameter_real inherit engine_idle_rpm

cos_engine_map spline inherit engine_map

cos_engine_max_rpm parameter_real inherit engine_revlimit_rpm

cos_engine_rpm solver_variable inherit engine_rpm

cos_engine_speed parameter_real inherit engine_speed

cos_max_engine_driving_torque solver_variable inherit engine_maximum_driving_torque

cos_max_engine_braking_torque

solver_variable inherit engine_maximum_braking_torque

cos_max_gears parameter_integer inherit max_gears

cos_max_throttle parameter_real inherit max_throttle

cos_powertrain_gse gse inherit powertrain_gse

cos_transmission_input_omega solver_variable inherit transmission_input_omega

cos_transmission_spline spline inherit transmission_spline

Note: The engine and clutch portion of the powertrain is implemented as a GSE (general state equation) element in solver. The gsesub associated with this element is available here.

The solver_variable "analysis_type" indicates whether the analysis is steady-state or dynamic. When the analysis_type is steady-state the engine torque map and transmission gear ratios are ignored.


Quad-Link Axle Suspension

Overview

The quad-link axle suspension template is an example of a dependent suspension model. The wheels are mounted at either end of a rigid beam so the movement of one wheel is transmitted to the opposite wheel causing them to steer and camber together. Solid beam axle suspensions are commonly used on the front of heavy trucks, where high-load carrying capacity is required.

Figure 10 Quad-Link Axle Suspension

Template name

_quad_link_axle

Major role

Suspension

Application


Adams/CarTemplates

182

Description

The quad-link axle suspension template represents a common design for solid axles suspensions. You can use the template as a front steerable suspension or as rear nonsteerable suspension.

You can set subsystems based on this template to kinematic or compliant mode. In kinematic mode, Adams/Car replaces the bushings that connect the lower and upper links to the body mount part with the corresponding purely kinematic constraints.

Files referenced

Bushing, spring, and damper property files

Topology

Spherical joints connect the upper and lower links to the solid axle. The draglink is attached to the bell crank. The bell crank moves the tie rod, which steers the wheels. Revolute joints connect the uprights to the solid axle. A joint force actuator locks the hub to the wheel carrier. The following table maps the topology of the template.

Parameters

Toe and camber variables define wheel spin axis, spindle part, and spindle geometry. The following table lists the parameters in the template.


jklhoo_lower_link_frame gel_lower_link mtl_lower_link_frame

jklhoo_upper_link_frame gel_upper_link mtl_lower_link_frame

jklsph_upper_link_axle gel_upper_link ges_axle

jklsph_lower_link_axle gel_lower_link ges_axle

jolrev_knuckle_axle gel_knuckle ges_axle

josrev_bell_crank_axle ges_bell_crank ges_axle

jossph_draglink_pitman_arm ges_draglink mts_draglink_steering

joshoo_draglink_bell_crank ges_draglink ges_bell_crank

jossph_tierod_knuckle ges_tierod gel_knuckle

jolrev_bearing gel_hub gel_knuckle

josinp_tie_rod_bell_crank ges_tierod ges_bell_crank




Communicators

Mount parts provide the connectivity from the template to body subsystems and steering. Output communicators publish toe, camber, steer axis, and wheel center location information to the appropriate subsystems and the test rig. The following table lists the input and output communicators.

Rack and Pinion Steering System

Overview

The rack and pinion steering system is usually found in passenger cars. The pinion gear translates the rotary motion of the steering wheel into the linear motion of the rack. The rack moves the tie rods back and forth to steer the vehicle.




ci[lr]_lower_link_frame mount inherit

ci[lr]_spring_upper_to_body mount inherit

ci[lr]_upper_link_frame mount inherit

cis_draglink_steering mount inherit






cos_suspension_ parameters_ARRAY any inherit


Note: The kinematic flag variable toggles between kinematic and compliant mode.

Adams/CarTemplates

184

Figure 11 Rack and Pinion Steering System

Template name

_rack_pinion_steering

Major role

Steering

Application


Description

A series of hooke joints, which connect the three steering column shafts, transmit motion from the steering wheel to the pinion. A revolute joint connects the lower column shaft to the rack housing. A bushing (torsion bar) connects the shaft to the pinion. A revolute joint connects the pinion to the rack housing.

In kinematic mode, a reduction gear is active and connects the steering input shaft revolute joint to the pinion revolute joint. The underlying Adams/View entity (a coupler) is active only in kinematic mode. The reduction gear (pinion to rack) converts pinion rotational motion to the rack translational motion. A


translational joint constrains the rack to the rack housing. An additional VFORCE provides the steering assist force.

Files referenced

Property file, mdi_steer_assis.ste, stored in the steer_assist.tbl of the shared Adams/Car database. It defines the steering assist vector force.

Topology


Parameters

A parameter variable switches between kinematic and compliant mode. You can set the activity of the steering assist vector force through the hidden parameter variable, steering_assist_active. A series of parameters define the maximum values of angle, rack displacement, rack force, and steering-wheel torque.



joshoo_intermediate_shaftinput ges_intermediate_shaft ges_steering_shaft

jostra_rack_to_rackhousing ges_rack ges_rack_housing

josrev_steering_wheel ges_steering_wheel mts_steering_column_to_body

josrev_pinion ges_pinion ges_rack_housing

joscyl_steering_column_to_body ges_steering_column mts_steering_column_to_body

josrev_steering_input_shaft ges_steering_shaft ges_rack_housing

jksfix_rigid_rack_housing_mount ges_rack_housing sws_rack_house_mount

steering_assist_vforce ges_rack ges_rack_housing

gksred_input_shaft_pinion_lock josrev_steering_input_shaft josrev_pinion

grsred_steering_wheel_column_lock josrev_steering_wheel joscyl_steering_column_to_body

grsred_pinion_to_rack josrev_pinion jostra_rack_to_rackhousing

Adams/CarTemplates

186

Communicators

The following table lists the input and output communicators.

Rear Driveline System

Overview

The rear driveline system template provides an example model of a driveline for rear-wheel drive (RWD) vehicles.


cis_rack_housing_to_ suspension_subframe

mount inherit

cis_rack_to_body mount inherit


co[lr]_tierod_to_steering mount front

cos_max_rack_ displacement parameter_real inherit

cos_max_rack_force parameter_real inherit

cos_max_steering_angle parameter_real inherit

cos_max_steering_torque parameter_real inherit

cos_steering_rack_joint joint_for_motion inherit


Note: The rack and pinion steering system template contains general spline elements. The gss_torsion_bar spline gives the torque as a function of the angular deflection of the input shaft relative to the pinion.

The template also contains a switch part, which lets you explore two different topological solutions. You can connect the steering rack housing to the body or to the suspension_subframe.


Figure 12 Rear Driveline System

Template name

_driveline_rwd

Major role

Driveline

Application

Full-vehicle assemblies

Description

The rotational motion of the front propshaft is transmitted to the rear shaft and from there to the diff outputs. Diff outputs should be connected to the driving wheels.

Files referenced

Bushing property files

Topology

The rear driveline template consists of a two-piece propshaft, a slip yoke, and a differential. For convenience, the template includes the propshaft input part for applying motion or torque. The propshaft input part attaches to the powertrain through a revolute joint. A bearing supports it at its aft.

Adams/CarTemplates

188

The front propshaft attaches to the support bearing through an inline joint primitive that prevents translation of the front propshaft perpendicular to the propshaft's spin axis.

Hooke joints transmit the motion to the slip yoke part. The slip yoke supports and transmits torque to the rear propshaft through a translational joint. The differential input shaft receives torque from the rear propshaft through a hooke joint.

The differential is an open design rather than a limited slip. Four bushings mount it to the body. Setting kinematic mode fixes the differential housing to the body and deactivates the bushings. The following table maps the topology of the template.

Parameters

The parameter variable final_drive_ratio defines the pinion to ring ratio.

Limitations

The rear driveline template uses a number of rotating parts. If the driveline dynamics are not of interest to you, then it is more efficient to apply direct drive torque to the wheels, because the rotating parts in the template might slow the numerical integration during the Analysis.


josrev_diff_input ges_diff_input ges_diff_housing

jolrev_diff_output gel_diff_output ges_diff_housing

jorrev_diff_output ger_diff_output ges_diff_housing

joshoo_propshaft_at_diff ges_propshaft_rear ges_diff_input

joshoo_propshaft_input_to_ front ges_propshaft_input ges_propshaft_front

joscon_propshaft_front_to_ yoke ges_propshaft_front ges_slip_yoke

jostra_propshaft_rear_to_yoke ges_propshaft_rear ges_slip_yoke

josrev_propshaft_input_to_ trans ges_propshaft_input mts_propshaft_input_to_powertrain

jksfix_diff_housing_to_body ges_diff_housing mts_diff_housing_to_body

josinl_support_bearing_to_propshaft_front

ges_support_bearing ges_propshaft_front

josori_support_bearing_orientation ges_support_bearing mts_propshaft_support_to_body

josinp_support_bearing_ location ges_support_bearing mts_propshaft_support_to_body

jksinl_support_bearing_to_ body ges_support_bearing mts_propshaft_support_to_body

grsdif_differential josrev_diff_input jolrev_diff_output

grsdif_differential josrev_diff_input jorrev_diff_output

grsdif_differential jolrev_diff_output jorrev_diff_output


Communicators

Output communicators of the type mount publish the left and right differential output shafts to the suspension templates and subsystems. The following table lists the input and output communicators.

Rigid Chassis

Overview

The rigid chassis template represents the base frame of a vehicle.

Figure 13 Rigid Chassis

Template name

_rigid_chassis


ci[lr]_tripot_to_differential location rear

cis_diff_housing_to_body mount inherit

cis_driveline_torque solver_variable inherit

cis_propshaft_input_to_ powertrain mount inherit

cis_propshaft_support_to_ body mount inherit

co[lr]_tripot_to_differential mount rear

Adams/CarTemplates

190

Major role

body

Application

Suspensions, tires, and steering systems in full-vehicle assemblies

Description

A single rigid body part models the chassis.

Files referenced

Shell elements create the chassis graphic. All the shell files are stored in the Adams/Car shared database, in the shell_graphics.tbl directory.

Topology

The ges_chassis part is unconstrained.

Parameters

The rigid chassis template defines a series of parameter variables, most of which are used to compute the aerodynamic forces acting on the body. The following table lists the parameters in the template. For a detailed description of the force function, see Force Function Description.

Force function description

Adams/Car expects air density and area parameter variables to be in model units.

As a result of an air stream interacting with the vehicle, forces and moments are imposed on the vehicle. Out of the three forces and three moments, only the most relevant ones are modeled in the template. The aerodynamic general force takes into consideration the drag force (longitudinal force) and torque (pitching moment and torque along the y-axis of the vehicle, in the SAE coordinate system). In detail:

F = 0.5 x AirDensity x DragCoeff x Area x VX(chassis)2T = F x DZ (RideHeight)

The pitching moment acts to transfer weight between the front and rear axles. It arises because the drag does not act at the ground plane. Therefore, it accounts for the elevation of the drag force.


pvs_aero_drag_active Integer No units

pvs_aero_frontal_area Real Area

pvs_air_density Real Density

pvs_drag_coefficient Real No units


Limitations

The rigid body modeling of the chassis does not account for torsional stiffnesses and other effects. You could create a more accurate representation of a chassis frame by connecting the multiple rigid bodies though spring dampers to take into account torsional stiffnesses and using modal flexibility.

Communicators

The rigid chassis template defines a series of mount part communicators. The assembly process matches them with the corresponding output communicators created in suspensions, steering, and other subsystems. The following table lists the communicators. Note that the output communicator

Adams/CarTemplates

192

tierod_to_steering (rear) allows the tierod_to_steering mount parts in the rear suspension to connect to the chassis body.


co[lr]_spring_to_body mount inherit

co[lr]_strut_to_body mount inherit

co[lr]_tierod_to_steering mount rear

co[lr]_tv_link mount inherit

co[lr]_uca_to_body mount any

co[lr]_upr_link_fr mount inherit

co[lr]_upr_link_rr mount inherit

cos_aero_drag_force force inherit

cos_body mount inherit

cos_body_subsystem mount inherit

cos_chassis_path_ reference mount inherit

cos_concept_to_body mount inherit

cos_diff_housing_to_body mount rear

cos_driver_reference mount inherit

cos_measure_for_distance mount inherit

cos_powertrain_to_body mount inherit

cos_propshaft_support_to_body mount rear

cos_rack_to_body mount inherit

cos_steering_column_to_ body mount inherit

cos_subframe_to_body mount inherit

cos_aero_force force inherit

Note: The rigid chassis light template (_rigid_chassis_lt) is exactly the same as the rigid chassis template (_rigid_chassis), but without the shell graphic geometry.


Simple Anti-Roll Bar System

Overview

The simple anti-roll bar system template represents a bar fitted transversely to the suspension. The bar is made out of steel or a user-defined material. The bar is installed in a vehicle to reduce the roll of the vehicle body as the vehicle takes a corner. It increases suspension roll rate.

Figure 14 Simple Anti-Roll Bar System

Template name

_antiroll_simple

Major role

Antiroll

Application

Suspension and full-vehicle analyses

Description

The anti-roll bar system template provides a simple model of anti-roll bar (also known as stabilizer bar). It consists of two bar halves connected by a torsional spring-damper component.

Adams/CarTemplates

194

Files referenced

Bushing property files

Topology

A revolute joint connects the two bar halves of the anti-roll bar system. Bushings then attach the bar halves to the body or to the suspension subframe. Drop links transmit the suspension motion to the bar ends. The drop links attach to the suspension with spherical joints and to the bar ends with convel joints.

The following table maps the topology of the anti-roll bar system template.

Parameters

A parameter variable (pvs_torsional_stiffness) defines the torsional stiffness of the spring-damper component. The following table lists the parameter, its value, and units.

Limitations

The anti-roll bar system template represents a simple approximation of a stabilizer bar. For more complex solutions, you would need to create a more accurate representation of the bar through the discretization of rigid bodies, nonlinear rods, or flexible bodies.

Communicators

Mount parts provide the connectivity to the suspension subsystems. An output communicator exports information about the location of the ARB pick-up point.

The joint: Connects part: To part:

jo[lr]sph_droplink_ upper_bal ge[lr]_droplink mt[lr]_droplink_to_suspension

jo[lr]con_droplink_to_arb ge[lr]_droplink ge[lr]_arb

josrev_arb_rev_joint ger_arb gel_arb

arb_torsion_spring (rotational spring)

ger_arb gel_arb


pvs_torsional_stiffness Real variable Nmm/Degrees


The following table lists the communicators that the template uses.

Tire System

Overview

The tire system template provides three basic functions:

• Supports vertical load.

• Develops longitudinal forces for acceleration and braking.


ci[lr]_arb_bushing_mount mount inherit

ci[lr]_droplink_to_suspension mount inherit

co[lr]_ARB_pickup location inherit

Notes: The spring-damper component applies a rotational action-reaction force between the two bar halves. The following linear equation describes the torque applied at the i marker:

Ta = -C(da/dt) - Kt (a - ANGLE) + TORQUEwhere:

• C is the damping term (defaults to 0 in the template).

• Kt is the torsional stiffness.

• a is the angle between the bar halves.

• ANGLE is the initial angular displacement.

• TORQUE is the torsional preload. Torque applied on the j marker is equal and opposite to the torque on the i marker.

Adams/CarTemplates

196

• Develops lateral forces for cornering.

Figure 15 Tire System

Template name

_handling_tire

Major role

Wheel

Application

Full-vehicle analyses

Description

The tire system template consists of wheel parts rigidly connected to mount parts. The tire contact patch forces are transformed in forces and torques applied at the hub. A series of user-written subroutines perform the force calculation depending on the tire property file that you selected. The contact type (string element) and the road property file determine the road model. For additional information about using Adams/Tire in Adams/Car, see the Adams/Tire online help.

Files referenced

The tire system template references a tire property file for each wheel part. The default tire property file is mdi_tire01.tir, stored the tires.tbl directory of the Adams/Car shared database.

../adams_tire/master.htm


Topology

A fixed joint connects the wheel part to the spindle mount part.

Communicators

Mount parts provide connectivity to the suspension subsystems, and output communicators publish information about tire forces and wheel orientation.

The following table lists the communicators in the tire system template.


ci[lr]_camber_angle parameter_real inherit

ci[lr]_suspension_mount mount inherit

ci[lr]_toe_angle parameter_real inherit

ci[lr]_wheel_center location inherit

cis_driveline_active parameter_integer inherit

co[lr]_rotor_to_wheel mount inherit

co[lr]_wheel_orientation orientation rear

cos_tire_forces_array_left array inherit

cos_tire_forces_array_right array inherit

Adams/CarTemplates

198

Torsion Bar Double-Wishbone Suspension

Overview

The torsion bar double-wishbone suspension template is a modified version of the standard Double-Wishbone Suspension. In this template, however, a torsion bar spring replaces the coil spring.

Figure 16 Torsion Bar Double-Wishbone Suspension

Template name

_double_wishbone_torsion

Major role

Suspension

Application


Description

In the torsion bar double-wishbone suspension template, a torsion bar spring replaces the coil spring used in the standard Double-Wishbone Suspension. The torsion bar consists of two bar halves connected by a


rotational SFORCE (joint torque actuator). The rotational SFORCE exerted between the two bar halves is a function of a torsional stiffness and of the relative rotation along the torsion bar longitudinal axis.

Files referenced


Topology

The torsion bar consists of two bar halves connected by a cylindrical joint and a joint torque actuator. The first half is rigidly connected to the lower control arm, and the second half is fixed to the mount part and gets rigidly connected to the chassis if you use the suspension in full-vehicle assemblies.

Parameters

The torsion bar double-wishbone suspension template includes additional parameter variables besides those described in the Double-Wishbone Suspension. The variable defining the torsional stiffness defines the torsion bar stiffness. Also, another parameter variable defines the torsional preload applied between the lower control arm and the torsion bar.

The following table lists the additional parameters.

Communicators


Trailing Arm Suspension

Overview

The trailing arm suspension template is one of the most simple and economical designs for independent suspensions.


pv[lr]_tbar_stiffness Real Nmm/Degrees

pvs_tbar_preload Real Nmm

Note: The torsion bar double-wishbone suspension template includes a toe adjustment. It uses an adjustable force Adams/Car element to reach a desired toe angle at static equilibrium.

Adams/CarTemplates

200

Figure 17 Trailing Arm Suspension

Template name

_trailing_arm

Major role

Suspension

Application


Description

The trailing arm suspension template is a simple non-steerable suspension design. You can deactivate the driveline simply by selecting inactive in the Toggle Driveline Activity dialog box. Note that it is possible to define the spring concentric to the damper just by moving the spring upper- and lower-seat hardpoints.

Files referenced

Bushing, spring, damper, bumpstop, and reboundstop property files


Topology

Trailing arms to the left and right sides mount to a rigid subframe that in turns connects to the body mount part through bushings. The arms alone locate the wheel centers. Springs and dampers act between the arms and the body mount parts. A static rotation control actuator locks the rotational degree of freedom of the hub during quasi-static analyses.

You can set the suspension to kinematic or compliant mode. Kinematic mode allows purely kinematic connections between the upper strut parts, arms, subframe, and mount parts, while compliant mode replaces the kinematic joints with their corresponding elastic elements.


Parameters

The driveline offset variable defines the driveline geometry. Toe and camber variables define wheel spin axis, spindle part, and spindle geometry.


jklhoo_upr_strut_to_body mtl_strut_to_body gel_upper_strut

jklrev_arm_inner_ pivot gel_arm ges_subframe

jksfix_subframe_to_body_fixed ges_subframe mts_subframe_to_body

jklhoo_lwr_strut_to_arm gel_lower_strut gel_arm

jolcyl_lwr_upr_ strut gel_upper_strut gel_lower_strut

joltra_tripot_to_ differential gel_tripot mtl_tripot_to_differential

jolcon_drive_sft_ int_jt gel_tripot gel_drive_shaft

jolrev_spindle_ upright gel_spindle gel_arm







Adams/CarTemplates

202

Communicators

Mount parts provide the connectivity from the template to the body subsystems. Output communicators publish toe, camber, steer axis, and wheel-center location information to the appropriate subsystems and the test rig. The following table lists the input and output communicators.

Twist Beam Suspension

Overview

The twist beam suspension is a dependent suspension model intended for use only as a rear suspension. It does not include a panhard rod.


ci[lr]_spring_to_body mount inherit











cos_suspension_ parameters_ARRAY

array inherit

Note: The kinematic flag variable toggles between kinematic and compliant mode.


Figure 18 Twist Beam Suspension

Template name

_twist_beam

Major role

Suspension

Application


Description

The twist beam suspension template represents a common rear dependent suspension design. It does not include a subframe. The suspension is non-steerable and intended to be used as a rear suspension only.

The twist beam is a flexible body generated using shell elements. Interface parts connect the flexible body to the rest of the suspension.

Adams/CarTemplates

204

You can toggle the suspension between kinematic and compliant modes. In addition, you can deactivate driveshafts.

Files referenced

Springs, dampers, and bushings property files. Also, the flexible body references the file PonteV.mnf, stored in the flex_bodies.tbl directory of the Adams/Car shared database.

Topology

A static rotation control actuator locks the rotational degree of freedom of the hub during quasi-static analyses.

The following table maps the topology of the twist beam suspension.

Parameters

In the twist beam suspension, toe and camber variables parameterize wheel spin axis, spindle part, and spindle geometry. The following table lists the parameters in the template.


jklhoo_upr_strut_to_body mtl_strut_to_body gel_upper_strut

jolcyl_lwr_upr_strut gel_upper_strut gel_lower_strut




jolhoo_strut_to_beam gel_lower_strut ipl_damper_lwr

jklrev_beam_to_body ipl_beam_to_subframe mts_body

jolrev_spindle_to_beam gel_spindle ipl_spindle_to_beam








Communicators



ci[lr]_spring_to_body mount inherit



cis_body mount inherit








Note: The integer parameter variables let you activate and deactivate the driveshafts. The kinematic flag variable toggles between kinematic and compliant mode.

Adams/CarTemplates

206

Reviewing Results

Adams/CarRequests

204

RequestsRequests contain standard displacement, velocity, acceleration, or force information that can help you investigate the results of simulations. You can also define other quantities (such as pressure, work, energy, momentum, and more) that you want output during a simulation.

Adams stores the requests in request files (.req).

Setting Request ActivityBy default, requests for each element type are active. You can, however, deactivate requests for a certain element type. Any activity changes will only be retained during the current session.

Note that for the bushing element, the activity switch is saved in the subsystem/assembly file.

To set request activity:

1. From the Standard Interface's Tools menu, select Request Activity.

2. Press F1 and then follow the instructions in the dialog box help for Toggle Request Activity.

3. Select OK.

Storing Request ActivityTo store the Requests activity, you should group activity using parameter variables, which are stored in subsystem files.

To store request activity in Template Builder:

1. Create a parameter variable to store the activity of the request as a 1 for active, 0 for inactive.

For example, pvs_request_activity.

2. Create a group with command language:

Tools -> Command Navigator, group -> create . See Group Create.

3. Add your requests to the group.

4. For the expr_active parameter of the group (1 = active, 0 = inactive), create a function that uses the parameter variable in step 1.

The commands might look as follows:

group create &group_name = ._my_template.my_request_activityobjects_in_group = ._my_template.request0, &._my_template.request1, &._my_template.request2, &._my_template.request3, &expr_active = (pvs_request_activity)

205Reviewing ResultsRequests

For more examples, investigate templates in the shared database that have the group kinematic_mode_active, which is used for the Kinematic Mode option.

Request 907Request 907 (req907) outputs displacement, velocity, accelerations, and body side-slip angle depending on the value of par(2) in the parameter list. Req907 is compatible with both dynamic and steady-state type analyses.

The definition of the parameters array and the resulting output is:

par(1) = Branch Flag 907par(2) = Request Type:

0 = Displacement(Angles in radians)1 = Velocities

(Translational vel. in KPH)(Angular velocity in radians/s)

2 = Accelerations (Translational acc. G's)(Rotational acc. in radians/s/2)

3 = Body Side Slip Angle in Radianspar(3) = id I marker par(4) = id J markerpar(5) = id RM marker

Any results with a magnitude less than 1e-7 are set to zero.

Adams/CarPlot Configuration Files

206

Plot Configuration FilesYou can plot the results of an analysis using the standard functionality in Adams/PostProcessor. To help you manage your plots, however, your template-based product provides plot configuration files that define a series of plots.

For information on Adams/PostProcessor, see the Adams/PostProcessor online help.

Learn more about plot configuration files:

• About Plot Configuration Files

• Creating Plots Using a Plot Configuration File

• Creating Plot Configuration Files

• Format of Plot Configuration Files

• Example Plot Configuration File

About Plot Configuration FilesPlot configuration files tell your template-based product:

• Which plots to create

• The layout of each page and the plots to be displayed on that page

• General settings and preferences, such as titles, labels, horizontal and vertical spacings, scaling, legend text and its attributes, axes positions and their attributes

• The mathematical expressions to be displayed for the plot axes

• The primary and secondary grid attributes for each plot

• The presentation of the plot i.e. whether it should show actual curves or the curve data in tabular format

• The text/images to be displayed for the header/footer of each page

• The date and analysis stamp related details

• The Note and Spec Line related details

The files now support multiple plots per page, and each plot can contain multiple axes. You can cross-plot multiple analyses of the same type using one plot configuration file.

Plot configuration files are TeimOrbit files and are stored in your database in the plot_configs.tbl directory. See TeimOrbit File Format.

../adams_ppt/master.htm

207Reviewing ResultsPlot Configuration Files

You can access the plot configuration file functionality in Adams/PostProcessor. Learn about creating a plot configuration file through the interface. Learn about using plot configuration files.

Creating Plots Using a Plot Configuration FileAfter you've run an analysis, you can view the series of plots defined in a plot configuration file. If your plot configuration file contains customization command keywords and it has created the plots and curves, you can have your template-based product invoke the macro that contains a command keyword in its user-entered command.

The plot configuration file specifies a subtitle for your plots. In addition, in the File Import dialog box you can:

• Add a title to all the plots.

• Plot results of multiple analyses on one plot using the Cross Plotting option.

• Change the look of your plot, such as fonts and size, using the Execute Custom Macros option. To use this option, you must have a macro that defines the commands to be executed.

To view the plots defined in a plot configuration file:

1. From the Review menu, select Postprocessing Window or press F8.

2. From the File menu, point to Import, and then select Plot Config File.

The File Import dialog box appears.

3. In the Analyses text box, enter the analysis or analyses from which you want to view results.

4. In the Plot Configuration File text box, enter the name of the plot configuration file defining the plots that you want to view.

5. In the Plot Title text box, enter the title to appear at the top of the plots.

6. Select Cross Plotting to plot analysis data on existing plots containing data from other analyses.

If you selected multiple analyses in the Analyses text box, your template-based product automatically plots the data from the different analyses on the same plots.

7. If you have customization command keywords in the plot configuration file you selected in Step 4, then select Execute Custom Macro.

Your template-based product invokes the macro which executes any commands that customize the plots.

8. Select OK.

Note: To modify plots and curves, you can use the command statement in each block to invoke macros, which must contain the modification commands. The macros must be contained in your current binary file, which can be either private or site.


208

Creating Plot Configuration FilesYou can create a plot configuration file containing all of the plots currently in Adams/PostProcessor or only a selected set of plots. Your template-based product stores the configuration files in the plot_config table of your default writable database. Learn about Setting the Writable Database.

To create a plot configuration file:

1. From the Review menu, select Postprocessing Window or press F8.

2. Create and configure plots as desired, including specifying labels and spacing. For example, you can create a set of plots and add subtitles to all of them that describe the type of analysis with which the plots are associated.

3. Customize plots to suit your requirements. e.g. you can assemble multiple plots on the same page by changing the page layout. To change the page layout, from the View menu, point to Page and then select Page Layouts. This will display the Page Layouts dialog box. Select the desired layout.

4. Change the appearance of the plot if you would like to see the curve data in tabular format. To change the plot to tabular format, click on the associated plot and check the checkbox for Table shown at the bottom left. This setting is saved in the plot configuration file and the plot will be seen in the tabular format when this file is imported in future.

5. Add Notes or Spec Lines to the plot. To do this, from the Plot menu, select Create Note or Create Spec Line. On the respective dialog box, specify the data for the Note or Spec Line.

6. Specify the text or images for the header/footer of the pages. To do this, select the required page and point to Header or Footer tabs shown at the bottom left area. Each of these tabs have subtabs like Left, Center and Right. You can specify the text/image for them. To specify image for the header/footer. Select any of these subtabs and set the Source to Image. This displays the Image field below the Source field. You can double-click in this field and browse to the required image for the header/footer in any location - Left, Center or Right.

7. Customize the appearance of legend, axes, curve, date and analysis stamp as per your requirement. To do this, you can select these entities from the plot or select their entries from the tree view. Depending on the type of entity, various options/tabs are available in the lower left corner to modify associated properties.

8. From the File menu, point to Export, and then select Plot Configuration File.

The Save Plot Configuration File dialog box appears.

9. In the Configuration File Name text box, enter the name for the plot configuration.

10. If you want to include all plots currently in the Plotting window, including every page, select All Plots.

11. If you did not select All Plots, in the Plot Name(s) text box, enter the names of the plots that you want to include in the plot configuration file.

12. In the Plots and Curves text boxes, enter command keyword to invoke the macro that customizes the plots and curves.


Your template-based product saves the command keyword with your plotting configuration file. After it creates the plots and curves, your plotting configuration file invokes the macro which contains the commands.

13. Select OK.

Your template-based product saves the command keyword with your plotting configuration file. After it creates the plots and curves, your plotting configuration file invokes the macro which contains the commands.

14. This exports the plot configuration file with the specified name. If you specify images for the header/footer of any page, these image files are copied to the location where the plot configuration file is saved.

Format of Plot Configuration FilesPlot configuration files consist of three data blocks:

• Page Data Block

• Plot Data Block

• Plot-Curve Data Block

Page Data Block

The Page data block has the following structure:

PAGE_LAYOUT NUMBER_OF_PLOTS PAGE_NAME HEADER/FOOTER

Header/Footer data: This section will be present only if you have specified text/image for any section (Left, Center or Right) of Header or Footer. The entries are present only for those sections for which the text/image is specified.

Plot Data Block

The plot data block has the following structure:

INDEXNAMETIME_LOWER_LIMITTIME_UPPER_LIMITLEGEND (subblock)PLOT_BORDER (subblock)PRIMARY_GRID (subblock)SECONDARY_GRID (subblock)LEGEND_BORDER (subblock)GRAPH_AREA (subblock)SPEC_LINE (subblock)NOTES (subblock)


210

PLOT_AXES_FORMAT (subblock)PLOT_AXES_LABELS (subblock)PLOT_AXES_TICS (subblock)PLOT_AXES_NUMBERS (subblock)COMMAND

command_keyword

After your template-based product creates each plot, it executes the following commands if you defined a command keyword:

acar custom_plots <command_keyword> & plot_name=<plot_name>

The command acar custom_plots <command_keyword> must already be created in the current session, either interactively or already present in the acar.bin, file.

Plot-Curve Data Block

The plot-curve data block has the following structure:

NAMEPLOTVERTICAL_AXISHORIZONTAL_AXISHORIZONTAL_EXPRESSIONHORIZONTAL_COMPONENTVERTICAL_EXPRESSIONVERTICAL_COMPONENTY_UNITSX_UNITSLEGEND_TEXTCOLOR red, blue, yellow, magenta, cyan, black, white, skyblue, midnight_blue, blue_gray,dark_gray, silver, peach, maizeSTYLE solid, dash, dotdash, dotSYMBOL none, x, o, plus, star, atLINE_WEIGHT Real value from 1-4COMMAND command_keywordHOTPOINTINCREMENT_SYMBOL

After your template-based product creates each curve, it executes the following commands if you defined a command keyword:

acar custom_plots <command_keyword> &analysis=<analysis> &plot_name=<plot_name> &vertical_data=<y> &horizontal_data=<x> &curve_name=<curve_name>


The command acar custom_plots <command_keyword> must already be created in the current session, either interactively or already present in the acar.bin, file.

Example Plot Configuration FileThe following is an example of an Adams/Car plot configuration file:

$--------------------------------------------------------------MDI_HEADER[MDI_HEADER]FILE_TYPE = 'plt'FILE_VERSION = 2.0FILE_FORMAT = 'ASCII'$-----------------------------------------------------------------------PAGE[PAGE]PAGE_LAYOUT = 11.0NUMBER_OF_PLOTS = 1.0PAGE_NAME = 'my_page'HEADER_LEFT_LINES = 1.0HEADER_LEFT_LINE_0_TEXT = 'Header Left'HEADER_LEFT_TEXT_FONT_SIZE = 7.0HEADER_LEFT_COLOR = 788529153.0FOOTER_RIGHT_LINES = 1.0FOOTER_RIGHT_LINE_0_TEXT = 'Footer Right'FOOTER_RIGHT_TEXT_FONT_SIZE = 15.0FOOTER_RIGHT_COLOR = 788529232.0$-----------------------------------------------------------------------PLOT[PLOT]INDEX = 0.0NAME = 'my_plot'TIME_LOWER_LIMIT = 0.0TIME_UPPER_LIMIT = 0.0(LEGEND){placement location fill grow_left grow_down font}'bottom right' 156.8,10.6 1 TRUE FALSE 7(PLOT_BORDER){color line_style line_weight}'BLACK' 'solid' 1.0(PRIMARY_GRID){color line_style line_weight} 'SILVER' 'solid' 0.5(SECONDARY_GRID){color line_style line_weight}'SILVER' 'solid' 0.5(LEGEND_BORDER){color line_style line_weight} 'BLACK' 'solid' 1.0(GRAPH_AREA){minX minY maxX maxY auto_graph_area}8.5989 8.1158 159.3194 88.3882 yes(SPEC_LINE){name color style location thickness}'new_spec_line' 'Coral' 'dotdash' 10.0,10.0 1.0(NOTES){name type color placement alignment location font autopos autogenerate numStrings}'my_analysis' 'analysis' 'BLACK' 'horizontal' 'center_top' 8.6,3.2 7 no yes 1STRING_1_TEXT = 'Analysis: test1_parallel_travel'


212

{name type color placement alignment location font autopos autogenerate numStrings}'my_date' 'date' 'BLACK' 'horizontal' 'center_top' 159.3,3.2 7 no yes 1STRING_1_TEXT = '15:52:54 11-MAY-98'{name type color placement alignment location font autopos autogenerate numStrings}'subtitle' 'subtitle' 'BLACK' 'horizontal' 'center_bottom' 84.0,89.5 7 no no 1STRING_1_TEXT = 'Subtitle Strimg'{name type color placement alignment location font autopos autogenerate numStrings}'header' 'table header' 'BLACK' 'horizontal' 'center_bottom' 0.0,0.1 1 no yes 1STRING_1_TEXT = 'Subtitle Strimg'{name type color placement alignment location font autopos autogenerate numStrings}'my_NOTE' 'note' 'BLACK' 'vertical' 'left_top' 95.4,58.7 10 yes no 1STRING_1_TEXT = 'Note String'(PLOT_AXES_FORMAT){axis_name type color placement scaling offset primary limits}'vaxis' 'vertical' 'BLACK' 'left' 'linear' 0.0 yes 0.000000,0.000000'haxis' 'horizontal' 'BLACK' 'bottom' 'linear' 0.0 yes 0.000000,0.000000(PLOT_AXES_LABELS){axis_name label color placement alignment font autopos offset location}'vaxis' 'No Units' 'BLACK' 'vertical' 'center_bottom' 7 0 9.4 -0.8,48.3'haxis' 'Time (sec)' 'BLACK' 'horizontal' 'center_top' 7 0 5.0 84.0,3.2(PLOT_AXES_TICS){axis_name auto_divisions use_divisions divisions increments minor_divisions color}'vaxis' 'yes' 'yes' 4 5.000 2 'BLACK''haxis' 'yes' 'yes' 3 5.000 2 'BLACK'(PLOT_AXES_NUMBERS){axis_name trailing_zeros decimal_places scientific_range font color}'vaxis' 0 4 -4,5 7.0 'BLACK''haxis' 0 4 -4,5 7.0 'BLACK' $---------------------------------------------------------------PLOT_CURVE[PLOT_CURVE]NAME = 'new_curve_1'PLOT = 'my_plot'VERTICAL_AXIS = 'vaxis'HORIZONTAL_AXIS = 'haxis'HORIZONTAL_EXPRESSION = 'toe_angle.TIME'HORIZONTAL_COMPONENT = 'toe_angle.TIME'VERTICAL_EXPRESSION = 'toe_angle.left'VERTICAL_COMPONENT = 'toe_angle.left'Y_UNITS = 'no_units'X_UNITS = 'time'LEGEND_TEXT = '1029:Toe angle.left'COLOR = 'red'STYLE = 'solid'SYMBOL = 'NONE'LINE_WEIGHT = 2.0HOTPOINT = 0.0INCREMENT_SYMBOL = 1.0$----------------------------------------------------------------PLOT_CURVE[PLOT_CURVE]NAME = 'new_curve_2'PLOT = 'my_plot'VERTICAL_AXIS = 'vaxis'HORIZONTAL_AXIS = 'haxis'


HORIZONTAL_EXPRESSION = 'steer_angle.TIME'HORIZONTAL_COMPONENT = 'steer_angle.TIME'VERTICAL_EXPRESSION = 'steer_angle.right'VERTICAL_COMPONENT = 'steer_angle.right'Y_UNITS = 'no_units'X_UNITS = 'time'LEGEND_TEXT = '1031:Steer Angle.right'COLOR = 'blue'STYLE = 'dash'SYMBOL = 'NONE'LINE_WEIGHT = 2.0HOTPOINT = 0.0INCREMENT_SYMBOL = 1.0


214

Running AnalysesUsing Adams/Car to analyze a virtual prototype is much like ordering a test of a physical prototype. You specify the virtual prototype by opening or creating an assembly that contains the appropriate components, or subsystems, that make up the prototype. For example, you create suspension assembly containing suspension and steering subsystems and the suspension test rig.

In Adams/Car, you can run suspension and full-vehicle analyses.

Adams/CarRunning Suspension Analyses

214

Running Suspension AnalysesYou perform suspension analyses, which in Adams/Car are quasi-static equilibrium analyses, to learn how a suspension controls the wheel motions and transmits load from the wheels to the chassis. To perform a suspension analysis, you first create or open a suspension assembly that contains the selected subsystems and the test rig. To create a suspension assembly, you can select any subsystem that has either a suspension or a steering major role.

Using Adams/Car, you can:

• Easily modify the topology and the properties of the components of your suspension.

• Run a standard set of suspension and steering maneuvers.

• View suspension characteristics through plots. Learn about suspension characteristics.

For a suspension analysis, you can specify inputs to:

• Move the wheels through bump-rebound travel and measure the toe, camber, wheel rate, roll rate, side-view swing-arm length, and other characteristics.

• Apply lateral load and aligning torque at the tire contact path and measure the toe change and lateral deflection of the wheel.

• Rotate the steering wheel from lock to lock and measure the steer angles of the wheels and the amount of Ackerman, which is the difference between the left and right wheel steer angles.

You specify the inputs to the analysis by typing them directly into an analysis dialog box or by selecting a loadcase file that contains the desired inputs.

During the analysis, the test rig articulates the suspension assembly in the specified number of steps and applies the inputs you specified. At each step, Adams/Car calculates over 38 suspension characteristics, such as toe and camber angle, track change, wheel-base change, wheel rate (vertical stiffness), and fore-aft wheel center stiffness. You can plot these characteristics and use them to determine how well the suspension controls the motions of the wheels. Based on the results, you can alter the suspension geometry or spring rates and analyze the suspension again to evaluate the effects of the alterations.

The following figure shows an overview of the suspension analysis process.

215Running AnalysesRunning Suspension Analyses

Setting up Suspension AnalysesBefore you submit a suspension analysis, you must set the Suspension Parameters that Adams/Car uses when calculating suspension characteristics.

To set parameters:

1. From the Simulate menu, point to Suspension Analysis, and then select Set Suspension Parameters.

2. Enter the necessary parameters as explained in the dialog box help for Suspension Analysis: Setup Parameters.

3. Select OK.

To set up suspension analyses:

1. From the Simulate menu, point to Suspension Analysis, and then select the analysis you want to set up.

2. Enter the vertical wheel travel and the other parameters needed to control the analysis.

3. Optionally, select one or more loadcase files (.lcf) from an Adams/Car database. Loadcase files are text files that contain the vertical wheel travel and other parameters needed to control a suspension analysis. If you regularly perform several kinds of suspension analyses using the same ranges of travel, you should consider creating loadcase files for these. You can then submit all the analyses without having to reenter travel parameters each time.

As you perform an analysis for which you did not create a loadcase file, Adams/Car temporarily creates one for you and deletes it after the analysis.

4. Specify the number of Solution Steps in the analysis.

5. Select OK.

External-File AnalysesYou can perform two types of external-file analyses:

• Loadcase Analysis

• Wheel-Envelope Analysis

Loadcase Analysis

A loadcase analysis reads the analysis inputs (for example, vertical wheel travel, steering travel, and static loads) from one or more existing loadcase files. When you supply more than one loadcase file, Adams/Car performs one analysis for each loadcase file. See an Example Suspension Loadcase File.

A loadcase analysis requires a suspension subsystem.

Each loadcase analysis produces a separate set of output files, such as .gra, .req, and .out.


216

To set up a loadcase analysis:

1. From the Simulate menu, point to Suspension Analysis, and then select External Files.

2. Enter the necessary parameters as explained in the dialog box help for External Files.

3. Select OK.

Wheel-Envelope Analysis

A wheel-envelope analysis generates wheel-center positions and orientations for use in packaging the wheel/tire within the wheel well (fender). The analysis sweeps the wheels through their vertical and steering travel in fixed increments based on information stored in a wheel-envelope input file (.wen). The positions and orientations for the left and right wheel centers are output to a wheel-envelope output file (.wev) for import into computer-aided design (CAD) packages. See an Example Wheel-Envelope Input File and Example Wheel-Envelope Output File.

A wheel-envelope analysis requires suspension and steering subsystems.

A wheel-envelope input file has the same format as a static loadcase file, however, Adams/Car ignores columns three through ten: left and right lateral force, aligning torque, brake force, and driving force.

You can create or modify wheel-envelope input files using the Curve Manager.

To set up a wheel-envelope analysis:

1. From the Simulate menu, point to Suspension Analysis, and then select External Files.

2. Specify one or more wheel-envelope input files that define the vertical wheel and steering inputs.

3. Press F1 and then follow the instructions in the dialog box help for External Files.

4. Select OK.

Roll & Vertical Force AnalysisA roll and vertical force analysis sweeps the roll angle while holding the total vertical force constant. The total vertical force is the sum of the vertical forces on the left and right wheels. You can specify the total vertical force used by the left and right actuators to move the wheels.

In contrast to the opposite wheel-travel analysis, the roll and vertical force analysis allows the wheels to seek their own vertical position.

To set up a roll & vertical force analysis:

1. From the Simulate menu, point to Suspension Analysis, and then select Roll & Vertical Force.

2. Enter the necessary parameters as explained in the dialog box help for Suspension Analysis: Roll & Vertical Force.

3. Select OK.


Static Load AnalysisDepending on the type of load you input, the static load analysis applies static loads to the spindle and the tire contact patches between the specified upper and lower load limits. A static load analysis requires a suspension subsystem.

To set up a static load analysis:

1. From the Simulate menu, point to Suspension Analysis, and then select Static Load.

2. Enter the necessary parameters as explained in the dialog box help for Suspension Analysis: Static Loads.

3. Select OK.

Steering AnalysisA steering analysis steers the wheels over the specified steering-wheel angle or rack travel displacement from the upper to the lower bound. The application of steering motion results in a wheel displacement at the specified wheel height.

A steering analysis requires a suspension and a steering subsystem.

To set up a steering analysis:

1. From the Simulate menu, point to Suspension Analysis, and then select Steering.

2. Enter the necessary parameters as explained in the dialog box help for Suspension Analysis: Steering.

3. Select OK.

Wheel-Travel AnalysesA wheel-travel analysis allows you to look at how the characteristics of a suspension change throughout the vertical range of motion of the suspension.

You can perform three types of wheel-travel analyses. As a minimum, all wheel-travel analyses require a suspension subsystem. These analyses can also include a steering subsystem.

• Opposite Wheel-Travel Analysis

• Parallel Wheel-Travel Analysis

• Single Wheel-Travel Analysis

The force limits for the left/right_vertical jack force are implemented as real numbers and are defaulted to -2.0E+04 and 4.0E+04 Newton.

You can modify the force limits in the Template Builder using the actuator modify dialog box (because actuators in Adams/Car are a topological element) or using the Command Navigator and modifying the corresponding variables.


218

For example, to modify the left-side actuator force limits from the default values in the Standard Interface after having an assembly already opened, you go to: Tools -> Command Navigator -> Variable -> Modify.

In the Variable Modify dialog box, select the desired limit variable (.assembly.testrig.jfl_jack_force.force_limits, in this case) and modify the values to the new force limits.

Opposite Wheel-Travel Analysis

An opposite wheel-travel analysis moves the left and right wheel through equal, but opposite, vertical amounts of travel to simulate body roll. The left and right wheels move over the specified jounce and rebound travel, 180o out of phase with each other. You specify the parameters to define the vertical wheel travel and the fixed steer value when you submit the analysis.

To set up an opposite wheel-travel analysis:

1. From the Simulate menu, point to Suspension Analysis, and then select Opposite Wheel Travel.

2. Enter the necessary parameters as explained in the dialog box help for Opposite Wheel Travel Analysis.

3. Select OK.

Parallel Wheel-Travel Analysis

A parallel wheel-travel analysis keeps the left wheel and right wheel heights equal, while moving the wheels through the specified bump and rebound travel.

To set up a parallel wheel-travel analysis:

1. From the Simulate menu, point to Suspension Analysis, and then select Parallel Wheel Travel.

2. Enter the necessary parameters as explained in the dialog box help for Suspension Analysis: Parallel Travel.

3. Select OK.

Single Wheel-Travel Analysis

A single wheel-travel analysis moves one wheel, either the right or left, through the specified jounce and rebound travel while holding the opposite wheel fixed in a specified position.

To set up a single wheel-travel analysis:

1. From the Simulate menu, point to Suspension Analysis, and then select Single Wheel Travel.

2. Enter the necessary parameters as explained in the dialog box help for Single Wheel-Travel Analysis.

3. Select OK.


Computation of Suspension and Steering Characteristics During suspension analyses, Adams/Car computes 38 different characteristics. The suspension and steering characteristics that Adams/Car computes are based on the suspension geometry, the suspension compliance matrix, or both. Suspension geometry refers to the position and orientation of suspension parts relative to ground as the suspension is articulated through its ride, roll, and steer motions. For example, the orientation of the spindle axes is used to compute the toe and camber angles.

The suspension compliance matrix refers to incremental movements of the suspension due to the application of incremental forces at the wheel centers. Adams/Car computes the suspension compliance matrix at each solution position as the suspension is articulated through its motion. Characteristics such as suspension ride rate and aligning torque camber compliance are computed based on the compliance matrix.

The suspension and steering characteristics are based on:

• Steer Axis Computation

• Definition of Compliance Matrix

Definition of Compliance Matrix

The compliance matrix for a system, [C], is defined as the partial derivatives of displacements with respect to applied forces:

[C] = [∂X/∂F]

If a system is assumed to be linear, the compliance matrix can be used to predict the system movement due to force inputs:

From this perspective, matrix element cij is the displacement of system degree of freedom i due to a unit force at degree of freedom j.

Adams/Car uses a 12 x 12 matrix relating the motion of the left and right wheel centers to units forces and torques applied to the wheel centers. This matrix has the form shown next:

X C F =


220

For example, element C(3,3) is the vertical motion of the left wheel center due to a unit vertical force applied at the left wheel center. Element C(3,9) is the vertical motion of the left wheel center due to a unit vertical force applied at the right wheel center. For an independent suspension without a stabilizer bar, C(3,9) is zero since a vertical force on the right wheel will not cause motion of the left wheel. The other elements of the compliance matrix are defined similarly.

Steer Axis Computation

Adams/Car needs the steer axis of a suspension to compute suspension characteristics, such as caster angle, kingpin inclination, scrub radius, and caster moment arm or caster trail. When you create a suspension template in Adams/Car, you must select the method Adams/Car will use to compute the steer axis and provide the necessary input information.

Adams/Car offers two methods for calculating suspension steer axes:

• Geometric Method

• Instant Axes Method

Both methods give accurate results, but the instant axis method is more general, because it can be used when the steer axis cannot be determined geometrically, such as in a five-link suspension. Currently, for a new suspension template the default is the geometric method.


Geometric Method

Using the geometric method, Adams/Car calculates the steer axis by passing a line through two non-coincident points located on the steer axis. To use the geometric method, you must identify a part or parts and two hardpoints that fix the steer axis.

For example, in a double wishbone suspension you might identify the wheel carrier part and Hardpoints located at the upper and lower ball joints. For a MacPherson strut suspension, you might identify the wheel carrier part and a hardpoint located at the lower ball joint for one point, and the strut rod and a hardpoint located where the strut attaches to the body for the second point.

Instant Axes Method

Using the instant axes method, Adams/Car calculates the left and right steer axes from the suspension's compliance matrix. While the calculation is performed numerically, it is best described in physical terms. To calculate the steer axis at a given suspension position, Adams/Car first locks the spring travel and applies an incremental steering torque or force in all directions (3 forces and 3 torques). Then, from the resulting translation and rotation of the wheel carrier parts, Adams/Car calculates the instant axis of rotation for each wheel carrier. The instant axes of rotation are the steer axes.

To use the instant axes method, you must identify a part and a hardpoint where Adams/Car should lock the spring travel. Adams/Car locks the spring travel by locking the vertical motion of the part you identify at the chosen hardpoint location. You can use any part and hardpoint, provided that locking the vertical motion of that part at that location locks the spring travel. For example, in suspensions using coil or leaf springs, a good choice is the lower spring seat (such as, the part and hardpoint where the spring acts on the suspension). For a double wishbone suspension sprung by a torsion bar on the lower control arm, choose the lower control arm at its connection to the wheel carrier. Locking the vertical motion of the lower control arm at this location eliminates rotation in the torsion bar. Do not choose the wheel center location and wheel carrier. If you do, Adams/Car calculates inaccurate steer axes.

In almost all suspensions, the wheel center lies outboard of the steer axis and the steer axis is angled rearward (caster angle > 0) and inward (kingpin inclination > 0) relative to vertical. When the wheels are steered (for example, rotated about the steer axis), the motion of the wheel centers has a vertical component. Locking the vertical motion of the wheel carrier at the wheel center eliminates this vertical component and gives an inaccurate steer axis.

When no steering subsystem is present, the steer axis that the instant axis method calculates is typically inaccurate for a steerable suspension because the inner tie rods attach to ground and are not free to move laterally. Therefore, when a steering subsystem is present, the motion Adams/Car excites by applying an aligning torque to the wheel carrier is not comparable to the steering motion.

Dynamic AnalysisA dynamic analysis actuates the suspension at the contact patch via user defined runtime function expressions or by referencing existing RPC3 files.

It is also possible to define a runtime function expression for the steering motion, therefore combining vertical excitation with steering sweeps.


222

Note that the Computation of Suspension and Steering Characteristics is currently not available for dynamic suspension analyses.

To set up a dynamic analysis:

1. From the Simulate menu, point to Suspension Analysis, and then select Dynamic.

2. Enter the necessary parameters as explained in the dialog box help for Suspension Analysis: Dynamic.

3. Select OK.

Example Suspension Loadcase FileIn Adams/Car, you can use loadcase files to specify different types of suspension analyses. The following is an example loadcase file.

$-----------------------------------------------MDI_HEADER[MDI_HEADER]FILE_TYPE = 'lcf'FILE_VERSION = 4.0FILE_FORMAT = 'ASCII'

$-----------------------------------------------UNITS[UNITS]LENGTH = 'mm'ANGLE = 'degrees'FORCE = 'newton'MASS = 'kg'TIME = 'second'$ $Generation Parameters: (Do Not Modify!)$ loadcase = 1$ nsteps = 10 $ bump_disp = 100.00 rebound_disp = -100.00$ steering_input = angle$ stat_steer_pos = 0.00$

$-----------------------------------------------mode[MODE]STEERING_MODE = 'angle'VERTICAL_MODE = 'length'

$-----------------------------------------------data[DATA]

$COLUMN: input type: type of input data: side:$ (c1) wheel z disp / force left$ (c2) wheel z disp / force right$ (c3) lateral force (y) left$ (c4) lateral force (y) right$ (c5 aligning torque (z-axis) left$ (c6) aligning torque (z-axis) right$ (c7) brake force (y) left$ (c8) brake force (y) right$ (c9) driving force (y) left$ (c10) driving force (y) right$ (c11) steering force / steer angle / rack travel{ whl_z_l whl_z_r lat_l lat_r align_l align_r brake_l brake_r drive_l drive_r steer}-100.0000 -100.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000-80.0000 -80.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000


-60.0000 -60.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000-40.0000 -40.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000-20.0000 -20.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.00000.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.000 20.0000 20.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.000040.0000 40.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.000060.0000 60.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.000080.0000 80.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000100.0000 100.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000

Example Wheel-Envelope Input FileThe following is an example of a wheel-envelope input file (.wen) that you can use to control a wheel-envelope analysis.

$--------------------------------------------MDI_HEADER[MDI_HEADER]FILE_TYPE = 'wen'FILE_VERSION = 5.0 FILE_FORMAT = 'ascii'

$--------------------------------------------UNITS [UNITS]LENGTH = 'mm'FORCE = 'newton'ANGLE = 'deg'MASS = 'kg'TIME = 'sec'

$--------------------------------------------MODE [MODE]STEERING_MODE = 'angle'VERTICAL_MODE = 'length'

$--------------------------------------------GRID[GRID]BOUNDARY_STEERING_GRID = 100.0 BOUNDARY_WHEEL_GRID = 20.0 INTERIOR_STEERING_GRID = 100.0INTERIOR_WHEEL_GRID = 20.0

$--------------------------------------------DATA[DATA]$COLUMN: input type: type of input data: side:$ (c1) wheel z disp / force left$ (c2) wheel z disp / force right $ (c3) lateral force (y) left$ (c4 lateral force (y) right$ (c5) aligning torque (z-axis) left $ (c6) aligning torque (z-axis) right$ (c7) brake force (y) left$ (c8 brake force (y) right$ (c9) driving force (y) left

Note: For wheel-envelope input files, Adams/Car ignores columns three through ten: (left and right) lateral force, aligining torque, brake force, and driving force.


224

$ (c10) driving force (y) right$ (c11) steering steer angle / rack travel $ {whl_z_l whl_z_r lat_l lat_r align_l align_r brake_l brake_r drive_l drive_r steer}-120.0 -120.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 -500.080.0 80.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 -500.090.0 90.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 -300.0 120.0 120.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 -200.0120.0 120.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 200.085.0 85.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 350.0 80.0 80.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 500.0 60.0 60.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 500.030.0 30.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 450.0 -30.0 -30.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 450.0-75.0 -75.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 500.0 -120.0 -120.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 500.0

Example Wheel-Envelope Output FileA wheel-envelope output file (.wev) contains a header and a data table, as explained next.

The first three lines comprise the header and contain the following information, in this order:

• Type of file

• Adams dataset title

• Date and time of file creation

The table that follows the header contains the following information:

• The first column shows the solution step number

• Columns 2-4 show the data for the left wheel center x, y, z

• Columns 5-7 show the data for the left wheel axis point x, y, z

• Columns 8-10 show the data for the right wheel center x, y, z

• Columns 11-13 show the data for the right wheel axis point x, y, z

The following is an example of a wheel-envelope output file:

Adams/Car Wheel Envelope Analysis Output File - acar_v10.0

Adams/Car Assembly

2000-01-19 16:41:21

1 -4.2702 -673.57 205.00 -348.83 -1611.7 170.29 7.0293 670.69 205.00 303.63 1620.7 107.88

2 -4.6463 -681.45 225.00 -344.63 -1621.7 206.15 6.7629 678.55 225.00 307.97 1628.3 139.91

3 -4.9532 -687.82 245.00 -340.16 -1630.0 239.60 6.5706 684.92 245.00 311.28 1634.4 170.26

4 -5.2433 -692.82 265.00 -334.67 -1637.0 271.40 6.3755 689.93 265.00 314.35 1639.0 198.89


5 -5.5240 -696.55 285.00 -328.07 -1643.0 301.70 6.1779 693.66 285.00 317.43 1642.1 225.76

6 -5.7905 -699.08 305.00 -320.38 -1648.0 330.44 5.9864 696.18 305.00 320.67 1643.8 250.76

7 -6.0372 -700.45 325.00 -311.59 -1652.1 357.51 5.8099 697.55 325.00 324.25 1644.1 273.76

8 -6.2583 -700.71 345.00 -301.72 -1655.3 382.78 5.6583 697.79 345.00 328.31 1643.0 294.55

9 -6.4469 -699.89 365.00 -290.74 -1657.8 406.03 5.5424 696.93 365.00 333.04 1640.3 312.88

10 -6.5953 -698.01 385.00 -278.64 -1659.4 426.98 5.4752 695.00 385.00 338.63 1636.2 328.39

... .......

Adams/CarOutput of Suspension Analyses

226

Output of Suspension AnalysesAdams/Car analyses output the following general suspension characteristics for all suspensions:

• Aligning Torque - Steer and Camber Compliance

• Camber Angle

• Caster Angle

• Dive Braking/Lift Braking

• Fore-Aft Wheel Center Stiffness

• Front-View Swing Arm Length and Angle

• Kingpin Inclination Angle

• Lateral Force - Deflection, Steer, and Camber Compliance

• Lift/Squat Acceleration

• Percent Anti-Dive Braking/Percent Anti-Lift Braking

• Percent Anti-Lift Acceleration/Percent Anti-Squat Acceleration

• Ride Rate

• Ride Steer

• Roll Camber Coefficient

• Roll Caster Coefficient

• Roll Center Location

• Roll Steer

• Side-View Angle

• Side-View Swing Arm Length and Angle

• Suspension Roll Rate

• Toe Angle

• Total Roll Rate

• Wheel Rate

For steered suspensions, Adams/Car analyses also output the following steering characteriscs:

• Ackerman

• Ackerman Angle

• Ackerman Error

• Caster Moment Arm (Mechanical Trail)

• Ideal Steer Angle

• Outside Turn Diameter

• Percent Ackerman

• Scrub Radius

• Steer Angle

227Running AnalysesOutput of Suspension Analyses

• Steer Axis Offset

• Turn Radius

Aligning Torque - Steer and Camber Compliance

Note: This help file is shared by several Adams products.

Description The aligning torque steer compliance is the change in steer angle due to unit aligning torque on the wheel. The aligning torque camber compliance is the change in camber angle due to a unit aligning torque on the wheel.

A positive aligning torque acts to steer the wheel to the left. For a positive steer angle, the wheel turns to the left. For a positive camber angle, the top of the wheel tilts away from the body.

Units degrees/(force*length)

Request Names • alt_steer_compliance.left

• alt_steer_compliance.right

• alt_camber_compliance.left

• alt_camber_compliance.right

Method alt_steer_compliance.left = C(6,6) + C(6,12)alt_steer_compliance.right = C(12,6) + C(12,12) alt_camber_compliance.left = C(4,6) + C(4,12)alt_camber_compliance.right= -C(10,6) + C(10,12)

Figure 1 Aligning Torque Loading for Steer and Camber Compliances


228

Camber Angle

Caster Angle


Description Camber angle is the angle the wheel plane makes with respect to the vehicle's vertical axis. It is positive when the top of the wheel leans outward from the vehicle body.

Note that the inclination angle, a measurement available in full-vehicle analyses, is the angle the wheel plane makes with respect to the road surface. The inclination angle is used for tire calculations.

Units Degrees or angle

Request Names • camber_angle.left

• camber_angle.right

Inputs Wheel-center axis (spin axis) unit vectors, left and right

Method camber_angle = -arcsin

Figure 2 Camber Angle

SZ



Dive Braking/Lift Braking

Description Caster angle is the angle in the side elevation (vehicle XZ plane) between the steering (kingpin) axis and the vehicle's vertical axis. It is positive when the steer axis is inclined upward and rearward.

Adams computes the steer axis using the geometric or instant axis method.

Units Degrees

Request Names • caster_angle.left

• caster_angle.right

Inputs • Steer (kingpin) axis unit vectors - left and right

• Road vertical unit vector (z)

• Road longitudinal unit vector (x)

Method Adams uses the direction cosines in the x- and the z-directions of the kingpin axis to calculate caster angle, such that:

sx = steer_axis road_x_axissz = steer_axis road_z_axiscaster_angle = rtod * arctan(sx/sz)

Figure 3 Caster Angle



230

Description Dive braking is the amount of front suspension compression per G of vehicle braking. Included in dive is suspension compression due to weight transfer plus suspension extension due to brake forces. Positive dive indicates that the front suspension compresses in braking.

Lift braking is the amount of rear suspension extension per G of vehicle braking. Included in lift is suspension extension due to weight transfer plus compression due to brake forces. Positive lift indicates that the rear suspension extends in braking.

Units mm

Request Names • dive.left

• dive.right


Fore-Aft Wheel Center Stiffness

Inputs • Compliance matrix

• Fraction of braking applied at this axle

• Loaded tire radius

• Tire stiffness

• Whole vehicle CG height

• Total vehicle weight

• Wheelbase

Method Adams first computes the longitudinal force percentage due to braking:

Fleft = Fright = Brake Ratio / 2.0and then the vertical force percentange due to weight transfer:

Wleft = Wright = Whole vehicle CG height/ (2 x Wheelbase)

For rear anti-lift, the weight transfer is a negative value.

These are forces at each wheel per unit total braking force.

Vertical deflections due to the vertical force are:

Zwleft = Wleft x C(3,3) + Wright x C(3,9)Zwright = Wleft x C(9,3) + Wright x C(9,9)

Vertical deflections due to tractive forces are as follows, where Rl is the loaded radius of the tire:

ZFleft = Fleft [C(3,1) - Rl x C(3,5)] + Fright[C(3,7) - Rl x C(3,11)]ZFright = Fleft [C(9,1) - Rl x C(9,5)] + Fright[C(9,7) - Rl x C(9,11)]

The dive is:

dive.left = (ZFleft + ZWleft + Wleft / Kt) Vehicle Weightdive.right = (ZFright + ZWright + Wright / Kt) Vehicle Weight



232

Front-View Swing Arm Length and Angle

Description The stiffness of the suspension in the fore-aft direction is relative to the body, measured at the wheel center.

Units Newtons/mm

Request Names • fore_aft_wheel_center_stiffness.left

• fore_aft_wheel_center_stiffness.right

Inputs Compliance matrix

Method Adams applies equal unit forces acting longitudinally at the wheel centers. It calculates the fore-aft wheel center stiffness as follows:

fore_aft_wheel_center_stiffness.left = 1 / C(1,1)fore_aft_wheel_center_stiffness.right = 1 / C(7,7)


Description The swing arm is the imaginary arm extending from the wheel's front elevation instant center of rotation to the wheel center. The swing arm has a positive length when the instant center is inward of the wheel center. The angle of the swing arm is the angle it makes to the horizontal. A positive angle is when the arm slopes outward and upward from the center of rotation to the wheel center.

The magnitude of the swing-arm length is limited to a maximum of 1000 meters.

Units Length - mm; angle - degrees

Request Names • fr_view_swing_arm_angle.left

• fr_view_swing_arm_angle.right

• fr_view_swing_arm_length.left

• fr_view_swing_arm_length.right



Method The change in vertical and lateral position and the front view rotation of the left wheel center due to a unit vertical force at the left wheel center is:

The left front view swing arm length and angle are:

fr_view_swing_arm_length.left =

fr_view_swing_arm_angle.left =

The change in vertical and lateral position and the front view rotation of the right wheel center due to a unit vertical force at the right wheel center is:

Yleft C 2 3, =

Zleft C 3 3, =

left C 4 3, =

Yleft2 Zleft

2 +1 2

left–

1–

Yleft Zleft tan–

Yright C 8 9, =

Zright C 9 9, =

right C 10 9, =


234

Kingpin Inclination Angle

The right front view swing arm length and angle are:

fr_view_swing_arm_length.right =

fr_view_swing_arm_angle.right =

Figure 4 Instant Center Front View (Lateral, Vertical)

Yright2 Zright

2 +1 2

right

tan1–

Yright Zright


Description The kingpin inclination angle is the angle in the front elevation between the steer axis (the kingpin axis) and the vehicle's vertical axis. It is positive when the steer axis is inclined upward and inward.

Units Degrees

Request Names • kingpin_incl_angle.left

• kingpin_incl_angle.right


Lateral Force - Deflection, Steer, and Camber Compliance

Inputs Kingpin axis unit vectors - left and right

Method Adams uses the direction cosines in the y-direction and the z-direction of the kingpin axis to calculate the kingpin inclination angle:

kingpin_incl_angle.left =

kingpin_incl_angle.right =

Figure 5 Kingpin Angle (Ø is the Kingpin Angle)

tan1–

DCOSY DCOSZ

tan1–

DCOSY– DCOSZ


Description The deflections at the wheel center due to unit lateral forces applied simultaneously at the tire contact patches. The forces are oriented as if in a right turn. Adams reports the lateral translational deflection, steer deflection (rotational deflection about the vertical axis), and the camber deflection (rotational deflection about the longitudinal axis). Positive deflection indicates a deflection to the right. Positive steer is a steer to the left. Positive camber compliance is when the wheels lean outward at the top.

Units Deflection - mm; Camber and steer - degrees


236

Request Names

• lat_force_defl_compliance.left

• lat_force_defl_compliance.right

• lat_force_steer_compliance.left

• lat_force_steer_compliance.right

• lat_force_camber_compliance.left

• lat_force_camber_compliance.right


• Tire radius - loaded

Method When the force is applied at the tire contact patch, Adams computes the deflection due to both the lateral force at the wheel center and the moment created around the wheel center. The total compliances are:

lat_force_defl_compliance.left = +[C(2,2) + Rl x C(2,4) + C(2,8) + Rl x C(2,10)]

lat_force_defl_compliance.right = +[C(8,2) + Rl x C(8,4) + C(8,8) + Rl x C(8,10)]

lat_force_steer_compliance.left = +[C(6,2) + Rl x C(6,4) + C(6,8) + Rl x C(6,10)]

lat_force_steer_compliance.right = +[C(12,2) + Rl x C(12,4) + C(12,8) + Rl x C(12,10)]

lat_force_camber_compliance.left = +[C(4,2) + Rl x C(4,4) + C(4,8) + Rl x C(4,10)]

lat_force_camber_compliance.right = -[C(10,2) + Rl x C(10,4) + C(10,8) + Rl x C(10,10)]

Figure 6 Lateral Force Loading for Deflection, Steer, and Camber Compliances


Lift/Squat Acceleration


Description Lift is the amount of front suspension extension (rebound) per G of vehicle acceleration. Squat is the amount of rear suspension compression (jounce) per G of vehicle acceleration. Lift and squat arise when the suspension reacts to longitudinal tractive forces, weight transfer forces, and, in dependent suspensions, to the differential input and output torques.

Units mm

Request Names Front suspensions:

• lift.left

• lift.right

Rear suspensions:

• squat_acceleration.left

• squat_acceleration.right


Suspension parameters array:

• suspension_type (independent/dependent)

Vehicle parameters array:

• sprung_mass

• cg_height

• wheelbase

• loaded_tire_radius

• tire_stiffness

• axle_ratio (final drive ratio, pinion ring gear ratio)

• drive_ratio (fraction of total drive torque directed to the suspension)

Suspension geometry:

• Track

Acceleration due to gravity (Ag)


238

Method The suspension lift or squat during acceleration arises due to the tractive forces, weight transfer, and, in live axles, due to the differential input and output torques, as well. The longitudinal tractive forces at the tire contact patches are:

Fleft = Fright = -drive_ratio / 2.0The vertical forces at the tire contact patch due to weight transfer are:

VWleft = VWright = - cg_height / (2 * Wheelbase)Live axles also react to the drive torques (input torque to the differential pinion and the left and right output torque from the differential). Given the longitudinal tractive forces, the input torque (TI) to the differential is:

TI = tire_loaded_radius * abs(Fleft + Fright) / axle_ratio

And the vertical force at the tire contact patches due to the drive torque is:

VTleft = -VTright = TI / TrackThe left and right output torque from the differential is:

TOleft = - tire_loaded_radius * FleftTOright = - tire_loaded_radius * Fright

The vertical deflections of the suspension due to drive torque are:

ZDleft = VTleft * C(3,1) + TOleft * C(3,5) + VTright * C(3,7) + TOright * C(3,11) + VTleft / tire_stiffnessZDright = VTleft * C(9,1) + TOleft * C(9,5) + VTright * C(9,7) + TOright * C(9,11) + VTright / tire_stiffness

Independent suspensions do not react to the drive torques. Therefore,

ZDleft = ZDright = 0.0The vertical deflections of the suspension due to tractive forces are:

ZFleft = Fleft * C(3,1) + Fright * C(3,7) ZFright = Fright * C(9,7) + Fleft * C(9,1)

The vertical deflections of the suspension due to weight transfer forces are:

ZWleft = VWleft C(3,3) + VWright C(3,9) + VWleft / tire_stiffnessZWright = VWleft C(9,3) + VWright C(9,9) + VWright / tire_stiffness

Finally, the lift/squat per G of acceleration is:

lift.left / squat_acceleration.left = (ZDleft + ZFleft + ZWleft) * sprung_mass * Ag

lift.right / squat_acceleration.right = (ZDright + ZFright + ZWright) * sprung_mass * Ag


Percent Anti-Dive Braking/Percent Anti-Lift Braking


Description Percent anti-dive braking for a front suspension and percent anti-lift braking for a rear suspension are the ratio of vertical suspension deflections caused by braking forces and torques to the deflections caused by weight transfer. During braking, the vertical deflections in a suspension from weight transfer can, in part, be cancelled by the vertical deflections caused by braking forces and torques in the suspension. Suspensions that exhibit this characteristic are said to have anti-dive or anti-lift geometry.

For front suspensions, percent anti-dive braking is positive when deflections caused by braking forces and torques act to extend or rebound the suspension. For rear suspensions, percent anti-lift braking is positive when the deflections caused by the braking forces and torques act to compress or jounce the suspension.

Units %


• anti_dive_braking.left

• anti_dive_braking.right

Rear suspensions:

• anti_lift.left

• anti_lift.right


240



• sprung_mass

• cg_height

• wheelbase


• tire_stiffness

• brake_ratio (fraction of braking done by the suspension)

• acceleration due to gravity (Ag)

Method The brake forces at the tire contact patch per G of longitudinal deceleration are:

Fleft = Fright = sprung_mass * Ag * brake_ratio / 2The brake torques reacted that the suspension reacts to are:

BTleft = loaded_tire_radius * FleftBTright = loaded_tire_radius * Fright

The weight transfer forces that the suspension reacts to are:

WTleft = sprung_mass * Ag * cg_height / wheelbase / 2 WTright = sprung_mass * Ag * cg_height / wheelbase / 2

The brake forces and torques that cause the suspension deflections are:

ZBleft = Fleft * C(3,1) + Fright * C(3,7) + BTleft * C(3,5) + BTright * C(3,11) + Fleft / tire_stiffnessZBright = Fleft * C(9,1) + Fright * C(9,7) + BTleft * C(9,5) + BTright * C(9,11) + Fright / tire_stifness

The weight transfer forces that cause the suspension deflections are:

ZWleft = WTleft * C(3,3) + WTright * C(3,9) + WTleft / tire_stiffnessZWright = WTleft * C(9,3) + WTright * C(9,9) + WTright / tire_stiffness

Finally, the percent anti-dive and percent anti-lift are:

anti_dive_braking.left = anti_lift.left = 100 * ZBleft / ZWleftanti_dive_braking.right = anti_lift.right = 100 * ZBright / ZWright


Percent Anti-Lift Acceleration/Percent Anti-Squat Acceleration


Description Percent anti-lift for a front suspension and percent anti-squat for a rear suspension are the ratio of vertical suspension deflections caused by tractive forces and drive torques to the deflections caused by weight transfer. During acceleration, the vertical deflections in a suspension from weight transfer can, in part, be cancelled by the vertical deflections caused by tractive forces and drive torques in the suspension. Suspensions that exhibit this characteristic are said to have anti-lift or anti-dive geometry. Note that a suspension that does not transmit tractive forces and drive torques (drive_ratio = 0.0) has zero anti-lift or anti-squat.

For front suspensions, percent anti-lift is positive when deflections caused by tractive forces and drive torques act to compress or jounce the suspension. For rear suspensions, percent anti-squat is positive when the deflections caused by the tractive forces and drive torques act to extend or rebound the suspension.

Units %


• anti_lift.left

• anti_lift.right

Rear suspensions:

• anti_squat.left

• anti_squat.right


242


Suspension parameters array:

• suspension_type (independent/dependent)


• sprung_mass

• cg_height

• wheelbase


• tire_stiffness

• axle_ratio (final drive ratio, pinion ring gear ratio)

• drive_ratio (fraction of total drive torque directed to the suspension)

Suspension geometry:

• Track

Acceleration due to gravity (Ag)


Method The longitudinal tractive forces at the tire contact patches are:

Fleft = Fright = -drive_ratio / 2.0The vertical forces at the tire contact patch due to weight transfer are:

VWleft = VWright = - cg_height / (2 * Wheelbase)Live axles also react with the drive torques (input torque to the differential pinion and output torque from the differential). Given the longitudinal tractive forces, the input torque (TI) to the differential is:

TI = tire_loaded_radius * abs(Fleft + Fright) / axle_ratio

And the vertical force at the tire contact patches due to the drive torque is:

VTleft = -VTright = TI / TrackThe left and right output torque from the differential is:

TOleft = - tire_loaded_radias * FleftTOright = - tire_loaded_radias * Fright

The vertical deflections of the suspension due to drive torque are:

ZDleft = VTleft * C(3,1) + TOleft * C(3,5) + VTright * C(3,7) + TOright * C(3,11) + VTleft / tire_stiffnessZDright = VTleft * C(9,1) + TOleft * C(9,5) + VTright * C(9,7) + TOright * C(9,11) + VTright / tire_stiffness

Independent suspensions do not react to the drive torque. Therefore,

ZDleft = ZDright = 0.0The vertical deflections of the suspension due to tractive forces are:

ZFleft = Fleft * C(3,1) + Fright * C(3,7)ZFright = Fright * C(9,7) + Fleft * C(9,1)

The vertical deflections of the suspension due to weight transfer forces are:

ZWleft = VWleft C(3,3) + VWright C(3,9) + VWleft / tire_stiffnessZWright = VWleft C(9,3) + VWright C(9,9) + VWright / tire_stiffness

The left and right percent anti-lift for front suspensions and percent anti-squat for rear suspensions are:

anti_lift.left / anti_squat.left = 100 * (ZFleft + ZDleft) / ZWleftanti_lift.right / anti_squat.right =100 * (ZFright + ZDright) / ZWright


244

Ride Rate

Ride Steer


Description Ride rate is the spring rate of the suspension relative to the body, measured at the tire contact patch.

Units Newtons/mm

Request Names • ride_rate.left

• ride_rate.right


• Tire stiffness

Method Adams computes ride rate as the equivalent rate of the wheel rate and tire rate in series.

Ks = Wheel rate (see Wheel Rate)Kt = Vertical tire rateKtotal = Ks x Kt / (Ks + Kt)


Description Ride steer is the slope of the steer angle versus the vertical wheel travel curve. Ride steer is the change in steer angle per unit of wheel center vertical deflection due to equal vertical forces at the wheel centers. Positive ride steer implies that the wheels steer to the right, as the wheel centers move upward.

Units Degrees/mm

Request Names • ride_steer.left

• ride_steer.right



Method Change in Wheel Orientation

Using the compliance matrix, Adams first calculates the change in wheel orientation (W) due to unit forces applied at both wheel centers:

Wl/dF = C(4, 3) - C(4, 9) , C(5, 3) - C(5, 9) , C(6, 3) - C(6, 9)Wr/dF = C(10, 3) - C(10,9) , C(11, 3) - C(11, 9) , C(12, 3) - C(12,9)

Change in Wheel-Center (Spin) Vector Orientation

The change in the left wheel-center (spin) vector (d(wcvl)) and the right wheel (spin) vector (d(wcvr) are vectors of partial derivatives given by the cross product of the change in wheel orientation with the wheel-center vector:

d(wcvl)/dF = Wl x wcvld(wcvr)/dF = Wr x wcvr

Change in Steer Angle

The change in steer angle due to a change in wheel-center vector orientation is also a vector of partial derivatives given by:

d(steer_anglel)/d(wcvl) = (-1.0 / ( syl**2 + sxl**2 ) ) { syl, -sxl, 0 }d(steer_angler)/d(wcvr) = (-1.0 / ( syr**2 + sxr**2 ) ) { syr, -sxr, 0 }

where:

sxl = wcvl o x; The x component of the left wheel-center (spin) vectorsyl = wcvl o y; The y component of the left wheel-center (spin) vector\sxr = wcvr o x; The x component of the right wheel-center (spin) vectorsyr = wcvr o y; The y component of the right wheel-center (spin) vector

The change in steer angle due to unit vertical forces at both wheel centers is computed by the chain rule:

d(steer_anglel) /dF = ( -d(steer_anglel)/d(wcvl) ) o ( d(wcvl) / dF )d(steer_angler)/dF = ( -d(steer_angler)/d(wcvr) ) o ( d(wcvr) / dF )


246

Roll Camber Coefficient

Change in Wheel-Center Vertical Travel

The change in wheel-center vertical travel (dz) due to unit vertical forces applied at both wheel centers is:

dzl /dF = { C(3,3) + C(3,9) }dzr /dF = { C(9,3) + C(9,9) }

Using the chain rule one final time, the ride steer is:

ride_steer.left = d(steer_anglel)/dzl = d(steer_anglel)/dF/(dF/dzl)ride_steer.right = d(steer_angler)/dzr = d(steer_angler)/dF/(dF/dzr)

Nomenclature • Bold, uppercase text, such as Wl, are vectors.

• Bold, lowercase text, such as wcvl, are unit vectors.

• X is the vector cross product operator.

• o is the vector dot product operator.

• * is the scalar multiplication operator.


Description Roll camber coefficient is the rate of change of wheel inclination angle with respect to vehicle roll angle. Positive roll camber coefficient indicates an increase in camber angle per degree of vehicle roll.

Units Unitless

Request Names • roll_camber_coefficient.left

• roll_camber_coefficient.right



• Tire stiffness

• Track width

Method Adams applies opposing unit forces acting vertically at the tire contact patches. The height difference between the tire contact patches is the following, where Kt is the vertical tire rate:

DZ = C(3,3) - C(3,9) - C(9,3) + C(9,9) + 2/KtThe vehicle roll angle is the rotation of the line through the tire contact patches:

Av = DZ / trackAdams measures the wheel inclination with respect to the line through the tire contact patches, which has two components. The first is from the vertical movement of the tire contact patch and is the same as the vehicle roll angle. The second is from the rotational compliance at the wheel center due to the vertical force:

Ac = - C(4,3) + C(4,9) (left side)= - C(10,3) + C(10,9) (right side)

The total wheel inclination is then:

Ai = Av - AcThe roll camber is then:

roll_camber_coefficient = (Av - Ac) / Av = 1 - Ac / Av

Figure 7 Roll Camber


248

Roll Caster Coefficient

Roll Center Location


Description Roll caster coefficient is the rate of change in side view steer axis angle with respect to vehicle roll angle. A positive roll caster coefficient indicates an increase in caster angle per degree of vehicle roll.

This calculation assumes that the steer axis (kingpin) is fixed in the suspension upright as in a double-wishbone or MacPherson strut suspension. The calculation, however, is not valid for suspensions where the steer axis is not fixed in the suspension upright, for example, a five-link front suspension used in Audi A4.

Units Unitless

Request Names • roll_caster_coefficient.left

• roll_caster_coefficient.right


• Tire stiffness

• Track width

Method Adams applies opposing unit forces acting vertically at the tire contact patches. The height difference between the tire contact patches is the following, where Kt is the vertical tire rate:

DZ = C(3,3) - C(3,9) - C(9,3) + C(9,9) + 2/KtThe vehicle roll angle is the rotation of the line through the tire contact patches:

Av = DZ / trackThe rotational compliance at the wheel center due to the vertical force is:

Ac = C(5,3) - C(5,9) (left side)= C(11,3) - C(11,9) (right side)

The roll caster is then:

roll_caster_coefficient = Ac / Av



Description Roll center location is the point on the body where the moment of the lateral and vertical forces exerted by the suspension links on the body vanishes.

Units

Request Names • roll_center_location.lateral_from_half_track

• roll_center_location.vertical

• roll_center_location.lateral_to_left_patch

• roll_center_location.lateral_to_right_patch


250

Roll Steer

Inputs • Compliance matrix at contact patches

• Contact patch location

Method Adams applies unit vertical forces (perpendicular to the road) at the tire contact and measures the resulting contact patch displacements in the vertical and lateral direction (front view). Adams projects lines perpendicular to the contact patch displacements for both the left and right patches. The roll center lies at the intersection of these lines.

Adams reports errors when the motions of the left and right patches are parallel (just as it occurs with a fully trailing arm suspension). Therefore, the projected lines have no intersection. Adams also reports an error when the motion of the left and/or right patches is very small for a unit vertical force (for example, the suspension is very stiff).

Finally, Adams limits the distance from the roll center to the left and right patches to +/- 1000 meters.

Figure 8 Roll Center Location (Front View)



Description Roll steer is the change in steer angle per unit change in roll angle, or the slope of the steer-angle-verses-roll-angle curve. Roll steer is positive when for increasing roll angle (left wheel moving up, right wheel moving down) the steer angle increases (wheels steer toward the left).

Units Unitless

Request Names • roll_steer.left

• roll_steer.right

Inputs • Wheel center spin axis unit vector (wcv) left and right

• Track

• Tire stiffness (Kt)

• Compliance matrix


252

Method Using the compliance matrix, Adams first calculates the change in roll angle and the change in the wheel-center vector orientation due to a roll moment (the roll moment is a unit vertical force upward at the left contact patch and a unit force downward at the right contact patch). Then, Adams calculates the change in steer angle due to the change in wheel-center vector orientation. Finally, Adams applies the chain rule to calculate the roll steer.

Change in Roll Angle

The change in roll angle is:

d(roll_angle)/d(roll_moment) = ( C(3,3) - C(3,9) - C(9,3) + C(9,9) + 2.0/Kt ) / Track

Change in Wheel-Center Spin Vector Orientation

The changes in orientation of the left wheel (Wl) and of the right wheel (Wr) due to a unit upward force at the left contact patch and a unit downward force at the right contact patch are:

Wl = { C(4, 3) - C(4, 9) , C(5, 3) - C(5, 9) , C(6, 3) - C(6, 9) }Wr = { C(10, 3) - C(10,9) , C(11, 3) - C(11, 9) , C(12, 3) - C(12, 9) }

The change in the left wheel-center (spin) vector (d(wcvl)) and the right wheel (spin) vector (d(wcvr) are vectors of partial derivatives:

d(wcvl)/d(roll_moment) = Wl x wcvld(wcvr)/d(roll_moment) = Wr x wcvr

Change in Steer Angle

The change in steer angle due to a change in wheel-center vector orientation is also a vector of partial derivatives given by:

d(steer_anglel)/d(wcvl) = (-1.0 / ( syl**2 + sxl**2 ) ) { syl, -sxl, 0 }d(steer_angler)/d(wcvr) = (-1.0 / ( syr**2 + sxr**2 ) ) { syr, -sxr, 0 }

where:

sxl = wcvl o x; The x component of the left wheel-center (spin) vectorsyl = wcvl o y; The y component of the left wheel-center (spin) vectorsxr = wcvr o x; The x component of the right wheel-center (spin) vectorsyr = wcvr o y; The y component of the right wheel-center (spin) vector


Side-View Angle

The change in steer angle for a change in roll moment is computed using the chain rule:

d(steer_anglel)/d(roll_moment) = ( d(steer_anglel)/d(wcvl) ) o ( d(wcvl)/d(roll_moment) )d(steer_angler)/d(roll_moment) = ( d(steer_angler)/d(wcvr) ) o ( d(wcvr)/d(roll_moment) )

Roll Steer

And applying the chain rule one last time, the roll steer is

roll_steer.left = ( d(steer_anglel)/d(roll_moment) ) / ( d(roll_angle)/d(roll_moment) )roll_steer.right = ( d(steer_angler)/d(roll_moment) ) / ( d(roll_angle)/d(roll_moment) )

Request Statements

REQUST/id, FUNCTION=USER(900,17,characteristics_input_array_id)

Nomenclature • Bold, uppercase text, such as Wl, are vectors.

• Bold, lowercase text, such as wcvl, are unit vectors.





Description The side-view angle is the wheel carrier side-view rotation angle. It is positive for a clockwise rotation, as seen from the left side of the vehicle.

Units Angle

Request Names • side_view_angle.left

• side_view_angle.right

Inputs Wheel bearing I marker and origo_y

Method side_view_angle = az, marker I, marker J


254

Side-View Swing Arm Length and Angle


Description The swing arm is an imaginary arm extending from the wheel's side elevation instant center of rotation to the wheel center. For front suspensions, the sign convention is that when the instant center is behind the wheel center, the swing arm has a positive length. For rear suspensions, the sign convention is the opposite: when the instant center is ahead of the wheel center, the swing arm has a positive length.

The angle of the swing arm is the angle it makes to the horizontal. A positive angle for a positive length is when the arm slopes downward from the wheel center. A positive angle for a negative length arm is when the arm slopes upward from the wheel center.

The magnitude of the swing-arm length is limited to a maximum of 1000 meters.

Units Length - mm; angle - degrees

Request Names • side_view_swing_arm_angle.left

• side_view_swing_arm_angle.right

• side_view_swing_arm_length.left

• side_view_swing_arm_length.right


Suspension Roll Rate


Method The change in vertical and longitudinal position and the side view rotation of the left wheel center due to a unit vertical force at the left wheel center is:

DX left = C(1,3) DZ left = C(3,3)DØ left = C(5,3)

The left side view swing arm length and angle are:

side_view_swing_arm_length.left = (DX left 2 + DZ left

2)1/2 / DØ left

side_view_swing_arm_angle.left = tan-1 (DX left / DZ left)

The change in vertical and longitudinal position and the change in side view rotation of the right wheel center due to a unit vertical force at the right wheel center is:

DX right = C(7,9)DZ right = C(9,9)DØ right = C(11,9)

The right side view swing arm length and angle are:

side_view_swing_arm_length.right = (DXright 2 + DZright

2) 1/2 / DØ right

side_view_swing_arm_angle.right = tan-1 (DXright / DZ right)

Figure 9 Instant Center Side View (Fore and Aft, Vertical)



256

Toe Angle

Description Suspension roll rate is the torque, applied as vertical forces at the tire contact patches, per degree of roll, measured through the wheel centers.

Units Newton-mm/degree

Request Names • susp_roll_rate.left

• susp_roll_rate.right


• Track width

Method Adams uses opposing unit forces as the applied torque:

T = F x track = trackThe resulting vertical distance between wheel centers is:

The rotation of the line through the wheel centers is:

The roll rate is:

susp_roll_rate = T / Ø =

Figure 10 Roll Rate - Suspension

Z X 3 3, X 3 9 ,– X 9 3 ,– X 9 9 ,+=

Z track=

track2

Z



Description Toe angle is the angle between the longitudinal axis of the vehicle and the line of intersection of the wheel plane and the vehicle's XY plane.

Adams reports toe angle in radians. It is positive if the wheel front is rotated in towards the vehicle body.

Units Degrees

RequestNames • toe_angle.left

• toe_angle.right

Inputs Wheel center axis unit vectors - left and right

Method Adams uses the direction cosines in the x- and y-directions of the wheel center axis relative to the road to calculate toe angle, such that:

toe_angle.left = tan-1 (DCOSX/DCOSY) toe_angle.right = tan-1 (-DCOSX/DCOSY)

Figure 11 Toe Angle


258

Total Roll Rate

Total Track


Description Total roll rate is the torque, applied as vertical forces at the tire contact patches, per degree of roll, measured at the tire contact patches.

Units Newton-mm/degreee

Request Names • total_roll_rate.left

• total_roll_rate.right


• Tire stiffness

• Track width

Method Adams uses opposing unit forces as the applied torque:

T = F x track = trackThe resulting vertical distance between wheel centers is the following, where Kt is the tire stiffnesses:

The rotation of the line through the tire contact patches is:

The roll rate is:

total_roll_rate = T/Ø =

Z C 3 3 , C 3 9 ,– C 9 3 ,– C 9 9 , 2 Kt+ +=

Z track=

track2

Z



Description Total track is the distance measured along the line passing through the left and right tire contact points with the left and right road parts (pads) and then projected onto the right road plane.

The tire contact point lies at the intersection of two lines:

• The first line is formed by the intersection of the wheel plane with the road plane.

• The second line is perpendicular to the first and passes through the wheel center.

The wheel plane is perpendicular to the wheel spin axis and passes through the wheel center.

The left and right road planes behave differently, depending on your coordinates:

• In vehicle coordinates, the left and right road planes remain perpendicular to the vehicle's vertical axis, but lie at different heights. If you run an opposite wheel-travel using vehicle coordinates, the left and right road planes remain un-rolled (flat) relative to the vehicle body (ground in a suspension analysis).

• In ISO coordinates, the left and right road planes form one plane that rotates about the vehicle's longitudinal axis to simulate rolling of the suspension relative to the road. If you run an opposite wheel-travel analysis using ISO coordinates, the right road plane and left road plane are identical, as if the suspension was rolled relative to a flat road. The total_track (distance between tire contact points) projected onto the right road plane is foreshortened, and therefore, is less than the total track output.

Also, the distance from the road plane to the wheel center depends on the tire deflection, which depends on the tire stiffness and the force required to deflect the suspension to a given position.

Units Length

Request Names • total_track


260

Wheel Rate

Ackerman

Inputs • Contact patch positions

Method The following is the equation used to compute total track:

T = ABS (ROAD (COMP, CPPLEFT) - ROAD (COMP, CPPRIGHT))

where:

• ROAD is a data structure filled with a series of kinematic characteristics of the suspension. ROAD (Y,CPPLEFT) returns, for

example, the Y component of the left contact patch position.

• CPP represents the instantaneous coodinates of contact points obtained as described above.


Description Wheel rate is the vertical stiffness of the suspension relative to the body, measured at the wheel center.

Units Newtons/mm

Request Names • wheel_rate.left

• wheel_rate.right


Method Adams computes suspension wheel rate as the inverse of the z-axis displacement at the wheel center due to the vertical forces applied at both wheel centers simultaneously.

wheel_rate.left = 1 / (C(3,3) + C(3,9))wheel_rate.right = 1 / (C(9,3) + C(9,9))



Ackerman Angle

Description Ackerman is the difference between the left and right wheel steer angles. A positive Ackerman indicates that the right wheel is being steered more to the right than to the left.

Units Degrees

Request Names • ackerman.left

• ackerman.right

Inputs Steer angle (see Steer Angle)

Method Adams/Car computes Ackerman by subtracting the right steer angle from the left steer angle:

ackerman = Right steer angle – Left steer angle


Description Ackerman angle is the angle whose tangent is the wheel base divided by the turn radius. Ackerman angle is positive for right turns.

Units Degrees

Request Names • ackerman_angle.left

• ackerman_angle.right


262

Ackerman Error

Inputs • Turn radius (see Turn Radius)

• Wheelbase

Method ackerman_angle = tan-1(Wheel Base/Turn Radius)

Figure 12 Ackerman Angle


Description Ackerman error is the difference between the steer angle and the ideal steer angle for Ackerman geometry. Because Adams/Car uses the inside wheel to compute the turn center, the Ackerman error for the inside wheel is zero.

For a left turn, the left wheel is the inside wheel and the right wheel is the outside wheel. Conversely, for a right turn, the right wheel is the inside wheel and the left wheel is the outside wheel. Positive Ackerman error indicates the actual steer angle is greater than the ideal steer angle or the actual is steered more to the right.

Units Degrees


Caster Moment Arm (Mechanical Trail)

Request Names • ackerman_error.left

• ackerman_error.right

Inputs • Steer angle (see Steer Angle)

• Ideal steer angle (see Ideal Steer Angle)

Method ackerman_error.left = (left steer angle - left ideal steer angle)

ackerman_error.right = (right steer angle - right ideal steer angle)


Description Caster moment arm is the distance from the intersection of the kingpin (steer) axis and the road plane to the tire contact patch measured along the intersection of the wheel plane and road plane. Caster moment arm is positive when the intersection of the kingpin axis and road plane is forward of the tire contact patch.

Units mm

Request Names • caster_moment_arm.left

• caster_moment_arm.right


264

Inputs • Kingpin axis position, a point on the kingpin axis (Rs) - left and right

• Kingpin (steer) axis unit vector (s) - left and right

• Tire contact patch position (Rp) - left and right

• Wheel center axis unit vector (w) - left and right

• The road normal unit vector (k)

Methods Adams/Car first finds the intersection of the kingpin axis and the road plane. Note that by convention, the kingpin axis unit vector is directed upward, away from the road, and the road plane has zero height. The intersection of the kingpin axis and the road plane (Rkr) is:

Rsr = Rs - (Rs o k)/(s o k) sNext, Adams/Car finds a unit vector (l) directed rearward along the line of intersection between the wheel plane and the road plane:

l = k x w / | k x w | (left side)l = k x -w / | k x -w | (right side)

The distance along l from the contact patch to the intersection of the kingpin axis and the road plane is:

caster_moment_arm = (Rp - Rkr) o l

Figure 13 Caster Moment Arm and Scrub Radius


Ideal Steer Angle

Outside Turn Diameter


Description Ideal steer angle is the steer angle in radians that gives Ackerman steer geometry or 100% Ackerman. For Ackerman steer geometry, the wheel-center axes for all four wheels pass through the turn center. Note that Adams/Car uses the steer angle of the inside wheel to determine the turn center for Ackerman geometry. Therefore, the ideal steer angle and the steer angle are equal for the inside wheel. When making a left turn, the left wheel is the inside wheel. Conversely, when making a right turn, the right wheel is the inside wheel. A positive steer angle indicates a steer to the right.

Units Degrees

Request Names • ideal_steer_angle.left

• ideal_steer_angle.right

Inputs • Turn radius (see Steer Angle)


• Wheelbase

Method ideal_steer_angle.left = tan-1 [Wheel Base/Turn Radius - Rp(left) o )]

ideal_steer_angle.right = tan-1 [Wheel Base/Turn Radius -Rp(right) o )]

Note • Right turns give positive angles and turn radii

• Rp(left) o < 0

• Rp(right) o > 0

• |Inside wheel's ideal steer angle| > |outside wheel's ideal steer angle|

y

y

y

y



266

Percent Ackerman

Description Outside turn diameter is the diameter of the circle defined by a vehicle's outside front tire when the vehicle turns at low speeds. Adams/Car determines the circle by the tire's contact patch for a given steer angle. For a left turn, the right front wheel is the outside wheel. For a right turn, the left front wheel is the outside wheel.

Units mm

Request Names • outside_turn_diameter.left

• outside_turn_diameter.right

Inputs • Turn radius (see Turn Radius)

• Track width

• Wheelbase

Method outside_turn_radius = 2.0 [(| Turn Radius | +Track/2)2 + (Wheel Base) 2]1/2


Description Percent Ackerman is the ratio of actual Ackerman to ideal Ackerman expressed as a percentage. Percent Ackerman is limited to the range from -999% to 999%. Percent Ackerman is positive when the inside wheel's steer angle is larger than the outside wheel's steer angle.

Units %

Request Names • percent_ackerman.left

• percent_ackerman.right


• Ideal steer angle (see Ideal Steer Angle)

• Ackerman (see Ackerman)

Method ackerman = Right steer angle - Left steer angle

ideal_ackerman = Right ideal steer angle - Left ideal steer angle

percent_ackerman = 100 x Ackerman/Ideal Ackerman


Scrub Radius


Description Scrub radius is the distance from the intersection of the kingpin (steer) axis and the road plane to the tire contact patch measured along the projection of the wheel-center axis into the road plane. Scrub radius is positive when the intersection of the kingpin axis and the road plane is inboard of the tire contact patch.

Units mm


268

Request Names • scrub_radius.left

• scrub_radius.right


Inputs • Kingpin axis position (Rs) - left and right

• Kingpin (steer) axis unit vector (s) - left and right


• Wheel-center axis unit vector (w) - left and right

• The road normal unit vector (k)

Method Adams/Car first finds the intersection of the kingpin axis and the road plane. Note that by convention the kingpin axis unit vector is directed upward, away from the road, and the road plane has zero height. The intersection of the kingpin axis and the road plane (Rkr) is:

Rsr = Rs - (Rs o k)/(s o k) sNext Adams/Car finds the projection (m) of the wheel-center axis (w) onto the road plane

M = (k x w) x k m = M / | M |

The distance from the contact patch to the intersection of the kingpin axis and the road plane along m is:

scrub_radius = (Rp - Rkr) o m

Figure 14 Caster Moment Arm and Scrub Radius


270

Steer Angle

Steer Axis Offset


Description Steer angle is the angle measured from the vehicle heading to the line formed by the intersection of the wheel plane with the ground plane. Steer angle is positive when a wheel is rotated to the right as if the vehicle were making a right turn.

Units Degrees

Request Names • steer_angle.left

• steer_angle.right

Inputs Wheel-center axis unit vectors - left and right

Method Adams/Car uses the direction cosines of the x-direction and the y-direction of the wheel-center axis constructed from the wheel-center orientation to calculate steer angle:

steer_angle.left = tan-1 (-DCOSX/|DCOSY|)steer_angle.right = tan-1 (DCOSX/|DCOSY|)



Description The steer axis offset is the shortest distance from the steer (kingpin) axis to the wheel center. The steer axis offset is measured in the plane perpendicular to the steer axis and passing through the wheel center. The steer axis offset is always positive.

The steer axis offset-longitudinal is the component of the steer axis offset along the intersection of the wheel plane with the plane perpendicular to the steer axis and passing through the wheel center. The steer axis offset-longitudinal is positive when the wheel center is forward of the steer axis.

The steer axis offset-lateral is the component of the steer axis offset along the projection of the wheel-center axis into the plane perpendicular to the steer axis and passing through the wheel center. The steer axis offset - lateral is positive when the wheel center lies outboard of the steer axis.

Units mm

Request Names • steer_axis_offset.off_left

• steer_axis_offset.off_right

• steer_axis_offset.lon_left

• steer_axis_offset.lon_right

• steer_axis_offset.lat_left

• steer_axis_offset.lat_right

Inputs • Wheel-center position (WCP) left and right

• Wheel-center (spin) axis unit vector (wcv) left and right

• Kingpin (steer) axis position (KPP) left and right

• Kingpin (steer) axis unit vector (kpv) left and right


272

Method First, define longitudinal and lateral directions in a plane perpendicular to the steer (kingpin) axis using the kingpin axis vector and the wheel-center (spin) vector.

u_lon = ( wcv x kpv ) / | wcv x kpv | and:

u_lat = ( kpv x u_lon ) / | kpv x u_lon |Note that u_lat is the projection of the wheel-center vector (wcv) onto the plane perpendicular to the kingpin axis.

The displacement vector (R) from a point on the kingpin (steer) axis to the wheel center is:

R = WCP - KPPThe steer axis offset-longitudinal is:

steer_axis_offset.lon_left = -R o u_lonsteer_axis_offset.lon_right = R o u_lon

The steer axis offset-lateral is:

steer_axis_offset.lat_left = R o u_lat steer_axis_offset.lat_right = R o u_lat

Finally, the steer axis offset is:

steer_axis_offset.off_left = sqrt( lon_left2 + lat_left2 )steer_axis_offset.off_right = sqrt( lon_right2 + lat_right2 )

Figure 15 Steer Axis Offset (Top View)


Turn Radius

Request Statements Offset:

REQUST/id, FUNCTION=USER(900,44,characteristics_input_array_id)\

Longitudinal offset:


Lateral offset:


Nomenclature • Bold text in uppercase letters, such as R, shows vectors.

• Bold text in lowercase letters, such as u_lon, shows unit vectors.





Description The turn radius is the distance measured in the ground plane from the vehicle center line to the turn center along the y-axis (see the figure for Ackerman Angle). Turn radius is positive for right turns and negative for left turns.

Units mm

Request Names • turn_radius.left

• turn_radius.right


274


• Track width

• Wheelbase

• Wheel-center orientations - left and right

Method Adams/Car determines the inside wheel by checking the sign of the steer angles. It computes turn radius using the inside tire orientation.

Left turn:

turn_radius.left = - [Wheel Base (DCOSY/DCOSX) + Track/2]

Right turn:

turn_radius.right = [Wheel Base x (DCOSY/DCOSX) + Track/2]

275Running AnalysesWorking with the Suspension Test Rig

Working with the Suspension Test RigAdams/Car uses the suspension test rig, named .__MDI_SUSPENSION_TESTRIG, in all its suspension analyses. When you create a suspension assembly, Adams/Car assembles the suspension test rig with the selected suspension and steering subsystems.

The suspension test rig inputs excitation as motions and forces to the suspension and steering subsystems. The excitations are made up of one or more of the following:

• Displacement for wheel bump and rebound vertical travel

• Roll and vertical force

• Steering travel at the steering wheel or rack

• Forces or torques at the steering wheel or rack

• Forces and torques at the contact patch and the hub

Learn about the suspension test rig:

• Benefits of Using the Suspension Test Rig

• Structure of Suspension Test Rig

Benefits of Using the Suspension Test RigYou can use the suspension test rig to:

• Include a deflecting tire in your suspension simulations so that suspension characteristics output by Adams/Car are more accurate.

• Swap a deflecting tire with a semi-rigid tire.

• Specify additional loads acting through the tire on the suspension, in particular:

• Lateral cornering force at the contact patch

• Lateral damage force and damage radius (point of application of force)

• Traction force acting at the wheel center (note that the traction torque is not reacted by the suspension)

• Braking force at the contact patch (creates a brake torque on the suspension)

• Overturning moment at the contact patch

• Aligning torque at the contact patch

• Drive your suspension with a set of closed-loop controllers to vary:

• Wheel-center displacements

• Contact patch displacements

• Wheel vertical forces

• Perform roll angle sweeps at constant total vertical force (sum of vertical force on the left and right wheels)

Adams/CarWorking with the Suspension Test Rig

276

Structure of Suspension Test RigYou assemble your suspension and steering subsystems with the suspension test rig. Then, using the resulting assembly, you simulate different suspension motions and loadcases to determine how your suspension performs. To help you to assess the performance of your suspension, Adams/Car calculates about forty characteristics, such as toe angle, camber angle, caster trail, roll center height, and aligning torque camber compliance.

When you assemble your suspension subsystem to the suspension test rig, the suspension arms, struts, links, and subframe that normally mount to the body, mount to ground. The test rig includes wheels and tires that mount to the suspension hubs. The test rig drives the suspension motion by tables that contact the tires, pushing the suspension up through the tires. Finally, if you include a steering subsystem, the test rig couples to the rack and the steering wheel to drive steering motion.

When you submit a suspension analysis you can request the test rig to control the wheel center or the tire contact patch positions. In some cases the test rig may not be able to achieve a desired position because the suspension travel is limited, for example, by a bumper. In such a case, the vertical actuators saturate, meaning they reach the maximum force they can apply. The forces and displacements the test rig can apply to the suspension through the vertical actuators are limited to reasonable values for passenger cars. For other vehicles, you may need to update the limits. To learn how to update the limits, see Vertical Actuators.

To properly assemble with the test rig, your suspension template must include the following output communicators (see Communicator Entity Class):

• suspension_mount (communicator entity class: mount) - Points to the parts (typically the hub, also known as the spindle) in your suspension template to which the test rig wheel tires mount.

• wheel_center_location (communicator entity class: location) - Contains the wheel-center location that Adams/Car uses to locate the test rig relative to the suspension.

• toe_angle and camber_angle (communicator entity class: parameter real) - Contain the static toe and camber angles that Adams/Car uses to orient the test-rig wheels.

• suspension_upright (communicator entity class: mount) - Points to the suspension upright in your suspension template. The suspension test rig creates a perpendicular joint primitive between the suspension mount (that is, the hub) and the suspension upright to lock wheel rotation during suspension analyses.

The following make up the suspension test rig:

• Vertical Actuators

• Suspension Test Rig Tire

• Static Loads

• Loadcase Files

Vertical Actuators

The left and right vertical actuators apply forces to drive the test-rig tables, and in turn, the suspension, up and down. An integral controller computes the actuator force necessary to achieve the desired wheel

277Running AnalysesWorking with the Suspension Test Rig

center or contact patch positions. However, the forces in the actuators are limited by default to -22,000 N in rebound and 40,000 N in jounce.

The vertical actuators are standard joint force actuators (pairs of action-only translational forces). You can modify the force limits using the Adams/Car Template Builder through the menus Build -> Actuator -> Joint Force -> Modify.

Suspension Test Rig Tire

The suspension test rig includes left and right wheel and tire UDE instances that are compatible with Adams/Tire. The test rig tables contact these tires to drive the suspension's vertical travel. These tires also apply the contact patch loads (read from the loadcase spline) to the suspension. The suspension test rig sets the simulation type string to ”SUSPENSION” to inform Adams/Tire you are performing a suspension analysis.

About RIGID_WHEEL and LIVE_TIRE

When working with these tires you can modify them to select either of the following:

• RIGID_WHEEL - The tire transmits both compression and tension force allowing the test rig to pull the suspension into rebound.

• LIVE_TIRE - The tire only transmits compression force. Thus when the vertical force between the tire and table goes to zero, the tire separates from the table. Therefore, when using a LIVE_TIRE, the test rig cannot pull the suspension into rebound. However, the force of gravity and the suspension spring will typically drive the suspension into rebound until the suspension hits the rebound bumper.

For the equations for RIGID_WHEEL and LIVE_TIRE,

• radius is the distance, measured in the plane of the wheel, from the wheel center to the contact patch

• r is the unit vector directed from the contact patch to the wheel center

• n is the unit vector normal to the table

RIGID_WHEEL

When you select RIGID_WHEEL, you enter the tire stiffness and unloaded radius. Adams/Car sets the tire property file string to ”RIGID_WHEEL” and passes the stiffness and radius you entered to Adams/Tire through an ARRAY statement. Adams/Tire calculates the tire vertical force using the following equation:

force = tire_stiffness*(unloaded_radius - radius) (r o n)

LIVE_TIRE

When you select LIVE_TIRE, you must enter a tire property file. Adams/Tire opens the property file and reads the unloaded radius and vertical stiffness. These values are automatically converted to the proper

Adams/CarWorking with the Suspension Test Rig

278

units for your suspension assembly. Other parameters in the tire property file are ignored. Adams/Tire calculates the tire vertical force using the following equation:

force = max(0.0, tire_stiffness*(unloaded_radius - radius) (r o n))

Static Loads

You can specify forces, torques, and displacements as inputs to your suspension analyses. These inputs are stored in the loadcase spline. The loadcase spline contains a linear interpolation at discrete time intervals, between the upper and lower values.

The following table shows how forces and torques are expressed in the reference frames :

Forces/Torques in Reference Frames

Loadcase Files

Adams/Car supports old suspension loadcase files (version 5) as follows:

• Vertical Mode = Length - Corresponds to wheel_center_height

• Vertical Mode = Force - Corresponds to an open-loop vertical force

Force/torque:

Reference frame:

TYDEX H ISO-W contact patch

TYDEX-C axis system wheel center

Lateral force (cornering) x

Longitudinal force (braking) x

Longitudinal force (traction) x

Overturning moment x

Rolling resistance torque x

Aligning torque x

279Running AnalysesTire Test Rig

Tire Test RigIn Adams/Car the response of a single tire under various conditions and excitations can be evaluated in the so-called Tire Testrig. The test rig can be activated by, after building an assembly, clicking on Simulate - Full-Vehicle Analysis - Tire Testrig.

The tire testrig model exists of one tire (wheel) mounted on a spindle that can be suspended to ground by a spring, or preloaded by an SFORCE, or fixed at a certain axle height.

The road can be fixed or moving (moving in x, y, z-direction, or rolling around x-axis), while the road it-self can be flat with or without a cleat (pothole), or user-defined (road property file).

The wheel movements can enhance steering (slip angle variations), wheel rotations (longitudinal slip variations), inclination with the road (camber), vertical and longitudinal wheel (center) displacements.

The initial wheel rotational speed can be calculated using the free tire radius in the tire property file and the initial wheel longitudinal velocity

Adams/CarTire Test Rig

280

Example testrig files, defining the testrig simulations, can be found in the loadcases folder of the Adams/Car database. The user may define own testrig simulations or modify one of these examples.

281Running AnalysesTire Test Rig

Each analysis represents one simulation. By clicking on the analysis name, the simulation details can be defined:

Once all analysis details have been defined, clicking on 'Run It' starts the process of generating the model files, run these with the solver and plotting a number of default characteristics in the postprocessor view.

Note: There are three points of attention when evaluating tire characteristics:

• For analyzing steady state tire characteristics, please remember that the usemode in the tire property file should be set to steady state (not transient)

• Some tire models have a 'start-up' smoothing option. This causes the tire response to start from zero up to the full tire force response during the first 0.1 seconds. For analyzing tire characteristics it is often useful to disable this option.

• The plots created for the Adams Postprocessor will be in MMKS units (mm, Newton, seconds, Kilogram).

Adams/CarRunning Full-Vehicle Analyses

282

Running Full-Vehicle AnalysesYou can take previously created suspension subsystems and integrate them with other subsystems to create a full-vehicle assembly. You can then perform various analyses on the vehicle to test the design of the different subsystems and see how they influence the total vehicle dynamics. All of the analyses, except for the data-driven analyses, use the .__MDI_SDI_TESTRIG, and are therefore based on the Driving Machine. You can also examine the influence of component modifications, including changes in spring rates, damper rates, bushing rates, and anti-rollbar rates, on the total vehicle dynamics.

Each type of analysis you perform requires a minimum set of subsystems: front and rear suspension subsystems, front and rear wheel subsystems, one steering subsystem, and one body subsystem. Before you can create an assembly and perform an analysis in Adams/Car, you must open or create the minimum set of subsystems required.

Using Adams/Car, you can:

• Easily modify the geometry and the properties of the components of your subsystems.

• Select from a standard set of vehicle maneuvers to evaluate handling characteristics of your virtual prototype.

• View the vehicle states and other characteristics through plots.

You can specify inputs to the analysis by typing them into an analysis dialog box or by selecting a driver control file that contains the desired inputs.

After specifying the prototype assembly and its analysis, Adams/Car, like your company's testing department, applies the inputs that you specified and records the results. To understand how your prototype behaved during the analysis, you can plot the results. After viewing the results, you might modify the prototype and analyze it again to see if your modifications improve its behavior.

The following figure shows an overview of the full-vehicle analysis process.

Setting up Full-Vehicle AnalysesBefore you set up a full-vehicle analysis, you must assemble and check the vehicle, as explained next:

• Assembling a Vehicle

283Running AnalysesRunning Full-Vehicle Analyses

• Checking a Vehicle

• Setting up the Analysis

Assembling a Vehicle

Adams/Car creates a full-vehicle assembly from a set of subsystems that you select. An assembly lets you quickly put together full vehicles from previously tested and verified subsystems and switch between subsystems depending on the analysis that you want to perform.

The associated component property files, such as springs and bushings, must also exist in your database.

If a suspension subsystem uses mount parts, such as the spring top mounting to a subframe, you must read the subframe subsystem into the assembly. If you do not read in the required mount subsystems, Adams/Car connects any mount parts to the global ground part instead of the absent mount subsystem. Therefore, the mount point cannot move with the full vehicle, which causes the Adams/Car analysis to fail.

Checking a Vehicle

Before submitting your model for analysis, visually check its assembly. The Adams/Car default view is front isometric view. From the front view, you should be able to see obvious assembly problems. You should also check your vehicle from the side because it provides a more useful view for positioning the subsystems.

As you view your assembly from different angles, check for obvious problems, such as:

• Is the front suspension in the correct place?

• Is the body graphic positioned correctly?

• Are the wheels somewhere near the same height?

All the analyses currently available are based on the Driving Machine. Therefore, to perform open-loop, closed-loop, and quasi-static analyses, you must select the .__MDI_SDI_TESTRIG in your assemblies. Always check whether you selected the correct test rig for the analysis you want to perform. If you selected an incorrect test rig, create another assembly using the correct test rig.

To check the test rig:

1. From the File menu, point to Info, and then select Assembly.

2. In the Assembly Name text box, enter the name of your assembly.

3. Select OK.

Adams/Car displays the Information window, with the test rig name listed at the top of the window.


284

Setting up the Analysis

To set up full-vehicle analyses:

1. From the Simulate menu, point to Full-Vehicle Analysis, and then select the analysis you want to set up.

2. Enter the parameters needed to control the analysis.

3. Typically, each transient analysis can be preceded by a quasi-static prephase analysis before running the transient analysis on your full-vehicle assemblies. A quasi-static prephase analysis consists of a straight analysis or a skidpad analysis, depending on the type of analysis you selected. If you do not select the quasi-static option, Adams/Car performs a SETTLE analysis.

For more information about the different quasi-static setup method keywords (such as SETTLE and STRAIGHT), see Structure of Event Files.

4. For dialog box help, select F1.

5. Select OK.

Controlling Full-Vehicle AnalysesIf you are an experienced Adams/Car user and you want to perform some non-standard full-vehicle analyses, such as studying the linear behavior of your vehicle between two mini-maneuvers, you can use an Adams/Solver control subroutine (Eventxxx) to do so.

When you run a full-vehicle analysis, Adams/Car writes a number of files to the current working directory (as defined by File -> Select Directory). These files contain important information about the details of the maneuver. In particular, two files are important in defining the scope of the maneuver. These are the Adams/Solver control file (.acf) and the event file (.xml). See Working with Event Files (.xml).

The following shows the typical contents of an .acf:

file/model=test_steppreferences/solver=F77output/nosepcontrol/ routine=abgVDM::EventInit, function=user(3,1,10,0,2,5,7,17)control/ routine=abgVDM::EventRunAll, function=user(0)!stop

In the .acf, note the following line:

control/ routine=abgVDM::EventInit, function=user(3,1,10,0,2,5,7,17)

This line calls an Adams/Car-specific control subroutine (a consub). The consub sets up and initializes the full-vehicle analysis. It does the following:

• Reads the event file (or converts the TeimOrbit .dcf file into XML)

• Performs a number of static analyses based on the content of the DcfStatic class in the event file


• Performs a dynamic analysis by running each of the mini-maneuvers listed in the DcfMini classes in the event file

You can view and modify the event file (.xml) using the Event Builder. The Event Builder allows you to modify existing parameters for the entire maneuver, such as step size and hmax, to modify specific mini-maneuver information, and add mini-maneuvers.

The following line calls the control subroutine EventInit:

control/ routine=abgVDM::EventInit, function=user(3,1,10,0,2,5,7,17)

The call to this subroutine passes 8 parameters, as described next. Note that each number in the array (3,1,10,0,2,5,5,17) is listed after the description of that parameter.

par(1) 3: ID of STRING statement containing .XML event filename = 3 par(2) ID of ORIGO marker = 1par(3) ID of ARRAY statement containing initial condition SDI parameters = 10par(4) ID of ARRAY statement containing ids of parts for which initial velocity are not set = 0par(5) ID of ARRAY holding Vehicle Parameters. = 2par(6) ID of main Driving Machine ARRAY. = 5par(7) ID ISO EAS Marker = 7par(8) ID of ARRAY containing the ids of extensible end condition sensor elements = 17

If you look at the corresponding Adams/Solver dataset (.adm), you will see that STRING/3 contains the name of the event file:

! adams_view_name='testrig_dcf_filename'STRING/3, STRING =example_crc.xml

All standard Adams/Car events generate an event file in XML format, similar to the one referenced in the example above, but .dcf files in TeimOrbit format are still supported, both in the Event Builder and at the solver level. This means that you can replace the above string and reference a .dcf file in TeimOrbit format. The file will be automatically converted to XML format.

By modifying the .acf file, you can now execute all mini-maneuvers defined in the event file, or just run the initialization and then execute one mini-maneuver at a time. Full-vehicle analysis .acf files by default call the Driving Machine initialization routine, then call the RunAll method. You can, however, modify the .acf file and use the following commands for more control over your analysis:

• control/ routine=abgVDM::EventRunAll, function=user(0) - Runs all the active mini-maneuvers in the list of events

• control/ routine=abgVDM::EventRunNext, function=user(0) - Runs the following mini-maneuver in the list of the events

• control/ routine=abgVDM::EventRunFor, function=user(double time) - Runs the current mini-maneuver for duration of time [s]

• control/ routine=abgVDM::EventRunUntil, function=user(double time) - Runs the current mini-maneuver until the desired absolute time [s]


286

Using this flexibility within the event control subroutine enables you to use the power of the acf language to make changes and re-submit your solution to Adams/Solver. The language parameters for the .acf file are documented in the Adams/Solver online help.

Running with External Adams/Solver

How you run Adams/Solver depends on the platform you are on:

• On Windows - The location of your .acf, .adm, and event files is important. Open a DOS shell (from the Start menu, point to Programs, point to Accessories, and then select Command Prompt) and change directory to the location where your files are stored (cd temp\run).

• On UNIX - Open a shell and change directory to the location of your files (cd /usr/home/user/temp/run).

To run external Adams/Solver:

• Issue the command:

adamsxx acar ru-solver filename.acf where:

• xx corresponds to the version of Adams that you are using

• filename.acf is the name of your acf file

Reading Results

After you run the analysis, you can use Adams/PostProcessor to animate and view the results.

3D Road AnalysisA 3D road analysis simulates your vehicle assembly traversing a three-dimensional road representation and the obstacles or characteristics contained in that 3D road. The road file (.rdf/.xml) is used by both the tire subsystems to compute contact patch forces/moments, and by the lateral controller. The Driving Machine uses path information contained in the 3D road file to drive the vehicle along the specified course centerline. Example 3D road files are distributed in the shared Adams/Car database (3d_road_*).

For more information about the 3D road, see Using the Road Builder.

Note: • To control the execution of the various mini-maneuvers defined in the XML event file you need to issue the EventInit control subroutine command first. This instructs Adams/Car to build a list of quasi-static and transient events as they are defined in the event file.

• To execute each mini-maneuver in the event file, you should issue a control/ routine=abgVDM::EventRunNext as described above.


To set up a 3D road analysis:

1. From the Simulate menu, point to Full-Vehicle Analysis, point to Course Events, and then select 3D Road.

2. Enter the necessary parameters as explained in the dialog box help for Full-Vehicle Analysis: 3D Road.

3. Select OK.

Cornering AnalysesYou use cornering analyses to evaluate your vehicle's handling and dynamic responses during various cornering-type maneuvers. Cornering analyses use both open- and closed-loop controllers of the steering, throttle, brake, gear, and clutch signals to investigate various vehicle behaviors. You can investigate both steady-state and limit cornering to characterize responses such as understeer/oversteer gradients, weight transfer, and so on.

The cornering analyses include:

• Braking-In-Turn

• Constant-Radius Cornering

• Cornering with Steer Release

• Lift-off Turn-in

• Power-off Cornering

Braking-In-Turn Analysis

The braking-in-turn analysis is one of the most critical analyses encountered in everyday driving. This analysis examines path and directional deviations caused by sudden braking during cornering. Typical results collected from the braking-in-turn analysis include lateral acceleration, variations in turn radius, and yaw angle as a function of longitudinal deceleration.

In a braking-in-turn analysis, you can set the Driving Machine to drive your full vehicle, as follows:

• Drive down a straight road, turn onto a skidpad, and then accelerate to achieve a desired lateral acceleration

• Run a quasi-static skidpad setup, which places the vehicle on a skidpad with predefined lateral acceleration

Note: Adams/Car creates an event file (.xml) that defines the analysis. The Driving Machine uses the event file to control the vehicle. Adams/Car stores the event file in the working directory so you can refer to it as needed and examine it using the Event Builder.


288

The Driving Machine holds the longitudinal speed and radius constant for a time to let any transients settle. It then applies a brake signal to the vehicle to control the vehicle deceleration at a constant rate (units in g).

Depending on the controller type, the Driving Machine does either of the following:

• Open-loop - Locks the steering wheel

• Closed-loop - Maintains the skidpad radius

The Driving Machine maintains the braking for the given duration of the maneuver or until the vehicle speed drops below 2.5 meters/second.

You can use the plot configuration file, mdi_fva_bit.plt, in the shared Adams/Car database to generate the plots that are typically of interest for this type of analysis.

To set up a braking-in-turn analysis:

1. From the Simulate menu, point to Full-Vehicle Analysis, point to Cornering Events, and then select Braking-In-Turn.

2. Enter the necessary parameters as explained in the dialog box help for Full-Vehicle Analysis: Braking-In-Turn.

3. Select OK.

Constant-Radius Cornering Analysis

For constant-radius cornering analysis, the Driving Machine drives your full vehicle down a straight road, turns onto a skidpad, and then gradually increases velocity to build up lateral acceleration. One common use for a constant radius cornering analysis is to determine the understeer characteristics of the full vehicle.

To set up a constant-radius cornering analysis:

1. From the Simulate menu, point to Full-Vehicle Analysis, point to Cornering Events, and then select Constant Radius Cornering.

2. Enter the necessary parameters as explained in the dialog box help for Full-Vehicle Analysis: Constant-Radius Cornering.

3. Select OK.

Cornering with Steer Release Analysis

The vehicle performs a dynamic constant-radius cornering to achieve the prescribed conditions (radius and longitudinal velocity or longitudinal velocity and lateral acceleration). After the steady state prephase, the steering wheel closed-loop signal is released, simulating a release of the steering wheel. The analysis focuses primary on the path deviation, yaw characteristics, steering-wheel measurements, roll angle, roll rate, and side-slip angle.


To set up an analysis of cornering with steer release:

1. From the Simulate menu, point to Full-Vehicle Analysis, point to Cornering Events, and then select Cornering w/Steer Release.

2. Enter the necessary parameters as explained in the dialog box help for Full-Vehicle Analysis: Cornering Steer Release.

3. Select OK.

Lift-off Turn-in Analysis

This analysis examines path and directional deviations caused by suddenly lifting the throttle pedal during cornering and applying an additional ramp steering input. Typical results collected from the lift-off turn-in analyses include lateral acceleration, variations in turn radius, and yaw angle as a function of longitudinal deceleration. Adams/Car drives the vehicle through two distinct phases:

• Cornering pre-phase: Adams/Car uses quasi-static calculations to set the vehicle at the correct initial conditions for the desired lateral acceleration at the given radius.

• Lift-off turn-in: The steer is ramped from the last value of the previous mini-maneuver at the desired rate. The throttle signal is set to zero; the clutch can be engaged or disengaged.

To set up a lift-off turn-in analysis:

1. From the Simulate menu, point to Full-Vehicle Analysis, point to Cornering Events, and then select Lift-Off Turn-In.

2. Enter the necessary parameters as explained in the dialog box help for Full-Vehicle Analysis: Lift-Off Turn-In.

3. Select OK.

Power-off Cornering Analysis

The purpose of this maneuver is to determine the power-off effect on course holding and directional behavior of a vehicle, whose steady-state circular path is disturbed only by power-off. The Driving Machine drives the vehicle through two distinct phases:

• An initial quasi-static setup that achieves the initial conditions.

• A power-off event where the throttle signal is stepped down from the value of the previous mini-maneuver to zero.

The lateral acceleration and skidpad radius define the initial conditions. Note that the significance of the results decreases with the skidpad radius. After reaching the initial steady-state driving conditions, the steering signal is kept constant and the accelerator pedal is released with a step signal profile. The release of the accelerator pedal is considered as the moment of power-off initiation, which you can define.

Typical results collected from power-off cornering analyses include variations in the heading direction and longitudinal deceleration, as well as side-slip angle, yaw angle, and gradient.


290

To set up a power-off cornering analysis:

1. From the Simulate menu, point to Full-Vehicle Analysis, point to Cornering Events, and then select Power-off Cornering.

2. Enter the necessary parameters as explained in the dialog box help for Full-Vehicle Analysis: Power-Off Cornering.

3. Select OK.

Course AnalysesCourse analyses are based on the Driving Machine and are of a course-following type, such as ISO lane change.

In an ISO lane change analysis, the Driving Machine drives your full vehicle through a lane change course as specified in ISO-3888: Double Lane Change. You specify the gear position and speed at which to perform the lane change. The analysis stops after the vehicle travels 250 meters; therefore, the time to complete the lane change depends on the speed you specify.

The course analyses include:

• ISO Lane Change

• 3D Road

ISO Lane Change

During an ISO lane change analysis, a longitudinal controller maintains the chassis velocity to the desired value, and a lateral controller module acts on the steering system to maintain the vehicle on the desired ISO lane-change path.

Adams/Car uses an external file to define the path for the maneuver: iso_lane_change.dcd defines the trace of the desired path on the x-y plane.

To set up an ISO lane change analysis:

1. From the Simulate menu, point to Full-Vehicle Analysis, point to Course Events, and then select ISO Lane Change.

2. Enter the necessary parameters as explained in the dialog box help for Full-Vehicle Analysis: ISO Lane Change.

3. Select OK.

Note: Adams/Car creates an event file (.xml) that defines the analysis and the different parameters. It uses the .xml file for the analysis and then leaves it in the working directory so you can refer to it as needed. The file that defines the path is stored in the shared_car_database, in the driver_data table, and is called iso_lane_change.dcd.


3D Road

A 3D road analysis simulates your vehicle assembly using a three-dimensional road representation. The road file (.rdf) is used by both the tire subsystems to compute contact patch forces/moments, and by the lateral controller. The standard driver interface (SDI) uses path information contained in the 3D road file to drive the vehicle along the specified course. The shared car database includes several example 3D road files.

To set up a 3D road analysis:

1. From the Simulate menu, point to Full-Vehicle Analysis, point to Course Events, and then select 3D Road.

2. Enter the necessary parameters as explained in the dialog box help for Full-Vehicle Analysis: 3D Road.

3. Select OK.

Open-Loop Steering AnalysesAdams/Car provides a wide range of open-loop steering analyses. In open-loop steering analyses, the steering input to your full vehicle is a function of time.

The open-loop steering analyses include:

• Drift

• Fish-Hook

• Impulse Steer

• Ramp Steer

• Single Lane-Change

• Step Steer

• Swept-Sine Steer

Drift Analysis

In a drift analysis, the vehicle reaches a steady-state condition in the first ten seconds. A steady-state condition is one in which the vehicle has the desired steer angle and initial velocity values. In seconds 1 through 5 of the analysis, Adams/Car ramps the steering angle/length from the initial value to the desired value using a STEP function. In seconds 5 through the desired end time, it linearly ramps the throttle at the desired ramp rate.

Note: Adams/Car creates an event file (.xml) that defines the analysis and the different parameters. It uses the .xml file for the analysis and then leaves it in the working directory so you can refer to it as needed.


292

To set up a drift analysis:

1. From the Simulate menu, point to Full-Vehicle Analysis, point to Open-Loop Steering Events, and then select Drift.

2. Enter the necessary parameters as explained in the dialog box help for Full-Vehicle Analysis: Drift.

3. Select OK.

Fish-Hook Analysis

You use a fish-hook analysis is to evaluate dynamic roll-over vehicle stability.

A fish-hook analysis consists of two mini-maneuvers (see Creating Mini-Maneuvers):

• A quasi-static phase sets up the vehicle at the desired initial conditions.

• The second mini-maneuver runs the actual fish-hook analysis in which Adams/Car computes the steering signal as a combination of step functions, and disengages the clutch. The maneuver provides a basis for evaluating a vehicle's transitional response and dynamic roll-over stability. The most important factors for this evaluation are: steering-wheel angle, lateral acceleration, yaw rate, and roll angle.

Adams/Car conducts the analysis by driving at a constant speed, putting the vehicle in neutral, and turning one direction in a preselected steering-wheel angle and then turning the opposite direction in another preselected steering-wheel angle.

To set up a fish-hook analysis:

1. From the Simulate menu, point to Full-Vehicle Analysis, point to Open-Loop Steering Events, and then select Fish Hook.

2. Enter the necessary parameters as explained in the dialog box help for Full-Vehicle Analysis: Fish Hook.

3. Select OK.

Impulse-Steer Analysis

In an impulse-steer analysis, the steering demand is a force/torque, single-cycle, sine input. The steering input ramps up from an initial steer value to the maximum steer value. You can run with or without cruise control. The purpose of the test is to characterize the transient response behavior in the frequency domain.

Typical metrics are: lateral acceleration, and vehicle roll and yaw rate, both in time and frequency domain.

To set up a impulse-steer analysis:

1. From the Simulate menu, point to Full-Vehicle Analysis, point to Open-Loop Steering Events, and then select Impulse Steer.

2. Enter the necessary parameters as explained in the dialog box help for Full-Vehicle Analysis: Impulse Steer.

3. Select OK.


Ramp-Steer Analysis

In a ramp-steer analysis, you obtain time-domain transient response metrics. The most important quantities to be measured are: steering-wheel angle, yaw angle speed, vehicle speed and lateral acceleration. During a ramp-steer analysis, Adams/Car ramps up the steering input from an initial value at a specified rate.

To set up a ramp-steer analysis:

1. From the Simulate menu, point to Full-Vehicle Analysis, point to Open-Loop Steering Events, and then select Ramp Steer.

2. Enter the necessary parameters as explained in the dialog box help for Full-Vehicle Analysis: Ramp Steer.

3. Select OK.

Single Lane-Change Analysis

During a single lane-change analysis, the steering input goes through a complete sinusoidal cycle over the specified length of time. The steering input can be:

• Length, which is a motion applied to the rack of the steering subsystem.

• Angle, which is angular displacements applied to the steering wheel.

• Force applied to the rack.

• Torque applied to the steering wheel.

To set up a single lane-change analysis:

1. From the Simulate menu, point to Full-Vehicle Analysis, point to Open-Loop Steering Events, and then select Single Lane Change.

2. Enter the necessary parameters as explained in the dialog box help for Full-Vehicle Analysis: Single Lane Change.

3. Select OK.

Step Steer Analysis

A step steer analysis yields time-domain transient-response metrics. The most important quantities to be measured are:

• Steering-wheel angle

• Yaw rate

• Vehicle speed

• Lateral acceleration

During a step steer analysis, Adams/Car increases the steering input from an initial value to a final value over a specified time.


294

To set up a step steer analysis:

1. From the Simulate menu, point to Full-Vehicle Analysis, point to Open-Loop Steering Events, and then select Step Steer.

2. Enter the necessary parameters as explained in the dialog box help for Full-Vehicle Analysis: Step Steer.

3. Select OK.

Swept-Sine Steer Analysis

Sinusoidal steering inputs at the steering wheel let you measure frequency-response vehicle characteristics. This provides a basis for evaluating a vehicle transitional response, the intensity and phase of which varies according to the steering frequency. The most important factors for this evaluation are:

• Steering-wheel angle

• Lateral acceleration

• Yaw rate

• Roll angle

During a swept-sine steer analysis, Adams/Car steers the vehicle from an initial value to the specified maximum steer value, with a given frequency. It ramps up the frequency of the steering input from the initial value to the specified maximum frequency with the given frequency rate.

To set up a swept-sine steer analysis:

1. From the Simulate menu, point to Full-Vehicle Analysis, point to Open-Loop Steering Events, and then select Swept-Sine Steer.

2. Enter the necessary parameters as explained in the dialog box help for Full-Vehicle Analysis: Swept-Sine Steer.

3. Select OK.

Quasi-Static AnalysesQuasi-static analyses find dynamic equilibrium solutions for your full vehicle at increasing, successive values of lateral acceleration. Quasi-static analyses, in contrast to open-loop and closed-loop analyses, do not include transient effects and solve very quickly. For example, in a quasi-static analysis, a change in lateral acceleration from 0.1g to 0.5g does not show the lateral acceleration or yaw rate overshoot that a similar open-loop and closed-loop analysis might show.

The following topics contain information on setting up quasi-static analyses, as well as a description of the types of quasi-static analyses:

• Quasi-Static Constant-Radius Cornering

• Quasi-Static Constant-Velocity Cornering

• Quasi-Static Force Moment Method


• Quasi-Static Straight-Line Acceleration

Quasi-Static Constant-Radius Cornering Analysis

You perform a constant radius cornering analysis to evaluate your full vehicle's understeer and oversteer characteristics. The constant radius cornering analysis holds the turn radius constant and varies the vehicle velocity to produce increasing amounts of lateral acceleration.

This analysis:

• Uses a force-moment method to balance the static forces to 0 at each time step.

• Provides a faster solution than the corresponding dynamic analysis, but doesn't account for transient effects, such as gear shifting.

• Can be useful when exploring the limit handling characteristics of the vehicle due to a combination of both the longitudinal and lateral acceleration.

• Differs from the constant-velocity cornering analysis in that the turn radius is fixed and the longitudinal velocity varies.

A CONSUB controls this analysis. For more information on CONSUB, see Welcome to Adams/Solver Subroutines.

You can, for example, use the plot configuration file, mdi_fva_ssc.plt, in the shared Adams/Car database to generate the plots that are typically of interest for this analysis. Otherwise, in Adams/PostProcessor, you can create your own plots by selecting the desired requests and components.

To set up a constant-radius cornering analysis:

1. From the Simulate menu, point to Full-Vehicle Analysis, point to Quasi-Static Maneuvers, and then select Constant-Radius Cornering.

2. Enter the necessary parameters as explained in the dialog box help for Quasi-Static Constant Radius Cornering.

3. Select OK.

Quasi-Static Constant-Velocity Cornering Analysis

You perform a constant velocity cornering analysis to evaluate your full vehicle's understeer and oversteer characteristics. The constant velocity cornering analysis holds the vehicle velocity constant and varies the turn radius to produce increasing amounts of lateral acceleration. The input parameters for this analysis are the same as the steady-state cornering analysis except that you specify the vehicle longitudinal velocity instead of the turn radius.

This analysis:

• Uses a force-moment method to balance the static forces to 0 at each time step.

• Provides a faster solution than the corresponding dynamic analysis, but doesn't account for transient effects, such as gear shifting.


296

• Can be useful when exploring the limit handling characteristics of the vehicle due to a combination of decreasing turn radius and longitudinal acceleration.

• Differs from the constant-radius cornering analysis in that the turn radius is not fixed.

A CONSUB controls this analysis. For more information on CONSUB, see Welcome to Adams/Solver Subroutines.

You can use the plot configuration file, mdi_fva_ssc.plt, in the shared car database to generate the plots that are typically of interest for this analysis.

To set up a constant-velocity cornering analysis:

1. From the Simulate menu, point to Full-Vehicle Analysis, point to Quasi-Static Maneuvers, and then select Constant-Velocity Cornering.

2. Enter the necessary parameters as explained in the dialog box help for Quasi-Static Constant Velocity Cornering.

3. Select OK.

Quasi-Static Force-Moment Analysis

You perform a force-moment analysis to evaluate the stability and handling characteristics of your vehicle model. During the analysis, Adams/Car drives the vehicle at constant longitudinal speed and performs a series of analyses at different side-slip angles and steer angles. The analysis:

• Represents a typical test in which the vehicle is constrained on a model flat-belt tire tester.

• Is based on the assumption that most of the stability and control characteristics can be obtained from a study of the steady-state force and moments acting on the vehicle.

You can present the results of a quasi-static force-moment analysis in tabular form or as diagrams and plots representing the computed forces and moments from the simulated test. The diagram created from the forces and moments acting on the vehicle is a portrait of the vehicle-maneuvering potential for specific operating conditions.

A CONSUB controls this analysis. For more information on CONSUB, see Adams/Solver Subroutines.

To set up a force-moment analysis:

1. From the Simulate menu, point to Full-Vehicle Analysis, point to Quasi-Static Maneuvers, and then select Force-Moment Method.

2. Enter the necessary parameters as explained in the dialog box help for Quasi-Static Force-Moment Method.

3. Select OK.

Quasi-Static Straight-Line Acceleration Analysis

A quasi-static straight-line acceleration analysis uses the static solver to perform multiple static analyses with each increasing time step representing an increase in straight line acceleration/deceleration. This technique uses a force-moment method to balance the static forces to 0 at each time step. This method


provides a quicker solution than the dynamic analysis but doesn't have transient effects, because of such events as gear shifting.

To set up a straight-line acceleration analysis:

1. From the Simulate menu, point to Full-Vehicle Analysis, point to Quasi-Static Maneuvers, and then select Straight-Line Acceleration.

2. Enter the necessary parameters as explained in the dialog box help for Quasi-Static Straight-Line Acceleration.

3. Select OK.

Straight-Line Behavior AnalysesThe analyses based on the Driving Machine focus on the longitudinal dynamics of the vehicle. Adams/Car uses open- and closed-loop longitudinal controllers to drive your vehicle model.

The straight-line-behavior analyses include:

• Acceleration

• Braking

• Power-off Straight Line

Acceleration Analysis

During an acceleration analysis, the Driving Machine ramps the throttle demand from zero at your input rate (open loop) or you can specify a desired longitudinal acceleration (closed loop). You can specify either free, locked, or straight-line steering. An acceleration analysis helps you study the anti-lift and anti-squat properties of a vehicle.

To set up an acceleration analysis:

1. From the Simulate menu, point to Full-Vehicle Analysis, point to Straight-Line Behavior, and then select Acceleration.

2. Enter the necessary parameters as explained in the dialog box help for Full-Vehicle Analysis: Acceleration.

3. Select OK.

Note: Adams/Car creates an event file (.xml) that defines the analysis and the different parameters. It uses the .xml file for the analysis and then leaves it in the working directory so you can refer to it as needed.


298

Braking Analysis

During a braking analysis, the Driving Machine ramps the brake input from zero at your input rate or lets you specify a longitudinal deceleration (closed loop). You can also specify either free or locked steering. The braking test analysis helps you study the brake-pull anti-lift and anti-dive properties of a vehicle.

To set up a braking analysis:

1. From the Simulate menu, point to Full-Vehicle Analysis, point to Straight-Line Behavior, and then select Braking.

2. Enter the necessary parameters as explained in the dialog box help for Full-Vehicle Analysis: Braking.

3. Select OK.

Power-off Straight Line Analysis

This analysis allows you to examine operating behavior and directional deviations caused by suddenly lifting off the throttle pedal during a straight-line analysis. Typical results collected from the power-off straight-line analysis include variations in heading direction and longitudinal deceleration. Optionally, you can depress the clutch during the throttle lift-off. In this case, you specify the duration that it takes to depress the clutch.

The Driving Machine drives the vehicle through two distinct phases:

• Quasi-static setup - The vehicle is set up in a straight line, to reflect the initial longitudinal velocity condition.

• Power-off event - The throttle signal is stepped down, from the value of the initial set mini-maneuver, to zero.

To set up a power-off straight line analysis:

1. From the Simulate menu, point to Full-Vehicle Analysis, point to Straight-Line Behavior, and then select Power-off Straight Line.

2. Enter the necessary parameters as explained in the dialog box help for Full-Vehicle Analysis: Power-Off Straight Line.

3. Select OK.

File-Driven AnalysisThe file-driven analysis lets you run an analysis described in an existing event file (.xml).

Having direct access to event files lets you perform non-standard analyses on your full-vehicle assembly because all you have to do is generate a new event file describing the analysis.

Learn about the Driving Machine.

Learn about Event Files.


To set up a file-driven analysis:

1. From the Simulate menu, point to Full-Vehicle Analysis, and then select File Driven Events.

2. Enter an Output Prefix.

3. If necessary, select a new Road Data File.

Press F1 for more detailed information on any of the selections in this dialog box.

4. Right-click in the Driver Control Files text box and select an XML Event file from the file selection dialog box.

5. Select OK.

Working with Event Files (.xml)

You use event files (.xml) to describe the maneuvers you want the Driving Machine to perform.

Event files (.xml) describe how you want the Driving Machine to drive your vehicle during a maneuver. The event file instructs the Driving Machine how fast to drive the vehicle, where to drive the vehicle (for example, on a 80 m radius skidpad), and when to stop the maneuver (for example, when lateral acceleration = 8 m/s2). Event files specify the kinds of controllers the Driving Machine should use for each of the available control signals (steering, throttle, brake, gear, and clutch). An event file can reference other files, primarily driver control data files (.dcd), to obtain necessary input data, such as speed versus time. Learn about referencing .dcd files.

Event files organize complex maneuvers into a set of smaller, simpler steps called mini-maneuvers. An event file defines the static-setup and a list of mini-maneuvers. For each mini-maneuver, the event file specifies how the Driving Machine is to control the steering, throttle, brake, gear, and clutch.

Learn about event files:

• Creating Event Files

• Structure of Event Files

• Creating Mini-Maneuvers

• Referencing .dcd Files

• Example Event Files

Creating Event Files

Before you can run a Driving Machine full-vehicle analysis, you must create (or use) an event file that contains one or more mini-maneuvers.

To set up Driving Machine mini-maneuvers:

1. From the Simulate menu, point to Full-Vehicle Analysis, and then select Event Builder.

The Event Builder dialog box has four major sections.

• File name, initial speed and gear, and units used in a selected field (shown at the bottom of the dialog box).


300

• Static Set-up and Gear Shifting Parameters.

• Mini-maneuver parameters on tabs for each of the five control signals with open-loop Control Value, plus an additional tab for Conditions to end a mini-maneuver.

• Closed-loop parameters (used when a control signal has its Control Method set to machine.


3. Enter the file name in the text box and click OK. The name appears in the Event File text box with a .xml extension. Initial default values appear in other text boxes.

4. If required, you can modify the initial Speed and Gear.

5. If required, you can modify values specified in the Static Set-up tab (for more information, see dialog box help for Event Builder).

6. Select the Gear Shifting Parameters tab. If required, you can modify values specified on this tab (for more information, see dialog box help for Event Builder).

7. If required, you can modify Machine Control control actions in the Trajectory Planning Parameter tab and Machine Control longitudinal and lateral PID Controller gains in the PID's Speed & Path and PID's Steering Output Parameters tabs (for more information, see dialog box help for Event Builder).

8. For MINI_1 (the default initial mini-maneuver), make selections for each of the control signal tabs (Steering, Throttle, Braking, Gear, and Clutch). Enter the necessary parameters as explained in the dialog box help for Event Builder to create the mini-maneuver.

9. Click the Conditions tab and enter the parameters required to end the mini-maneuver (for more information, see Specifying Conditions).

10. To create additional mini-maneuvers, click the button to the left of the mini-maneuver Name. This displays the Table Editor for mini-maneuvers.

11. In Table Editor mode, enter the name of your new mini-maneuver in the Name text box at the bottom of Event Builder.

12. Click Add. This adds a row to the Table Editor. You can edit any of the values in the row by clicking in the appropriate cell (for more information, see dialog box help for Event Builder).

13. Continue adding mini-maneuvers as necessary.

14. To return to Property Editor mode, either double-click a name (in the Name column), or select the name, right-click, and then select Modify with Property Editor.

15. When you've finished creating your event file, select Save.

After you create the file, you use it to run a file-driven analysis.

Learn about Structure of Event Files.

Using Event Files

After you use the Event Builder to create or modify an event file, you use that event file to run a file-driven analysis.


Creating Mini-Maneuvers

A mini-maneuver is a set of smaller, simpler analysis steps, such as a straight-line mini-maneuver. Mini-maneuvers are contained in event files (.xml).

To create a mini-maneuver, you must specify controls signals (steering, throttle, braking, gear, and clutch) and its conditions. For each control signal, you specify the following:

• Actuator type (steering only)

• Control method

• Control type

• Control mode

Learn more:

• Specifying an Actuator Type

• Specifying a Control Method

• Specifying a Control Type

• Specifying a Control Mode

• Specifying Conditions

Specifying an Actuator Type

When defining the steering control for a mini-maneuver, you must specify an actuator type. You use the actuator type to specify whether the Driving Machine steers the vehicle at the steering wheel or steering rack and whether the Driving Machine uses a force or motion. For example, when you set Actuator Type to rotation, the Driving Machine steers using a motion on the steering wheel.

The actuator type you select for steering determines how the Driving Machine interprets the units of other parameters associated with the steering signal. For example, if you set Actuator Type to torque, the Driving Machine interprets the amplitude argument for an open-loop sinusoidal input as torque (with units of length*force). If you set Actuator Type to rotation, however, the Driving Machine interprets the amplitude as an angle.

Arguments

force Driving Machine steers the vehicle by applying a force to the steering rack.

rotation Driving Machine steers the vehicle using a MOTION statement on the steering-wheel revolute joint.

torque Driving Machine steers the vehicle by applying torque to the steering wheel.

trans Driving Machine steers the vehicle using a motion on the steering rack translational joint.


302

Specifying a Control Method

When defining any mini-maneuver, you must specify a control method for each control signal.

Arguments

• Open

• Machine

• SmartDriver

Open Control Method

The Driving Machine output for the control signal is a function of time, and you must specify the function using the Control Type argument.

You cannot switch from an open-loop control mini maneuver to a human control mini maneuver. You can, however, switch from human control in a preceding mini maneuver to open-loop control in a subsequent mini maneuver.

Machine Control Method

Setting Control Method to machine specifies the vehicle path, speed profile, and other parameters used by machine control.

If you set machine control for gear and clutch, you must also supply the maximum and minimum engine speed. Machine control up-shifts to keep engine speed less than maximum and down-shifts to keep engine speed greater than minimum.

If you set Control Method to machine for steering, then you should specify the target path, using the Steer Control argument.

If you set Control Method to machine for throttle or brake, then you should specify the target speed profile, using the Speed Control argument.

Note: • If you set Speed Control to lat_accel, then you must set Steer Control to skidpad.

• Machine control for throttle requires the use of machine control for braking. Likewise, machine control for clutch requires machine control for gear.


Arguments


304

Steer Control You can select one of the following:

• ay_s_map/ay_t_map - To define these closed-loop steering conditions, you can use a Table/Plot editor that you access by selecting the Table Editor button.

• file -

• File Name - Enter the name of a file that contains the path data.

• path_map - To define this closed-loop steering condition, you can use a Table/Plot editor that you access by selecting the Table Editor button. To define this closed-loop steering condition, you can use a Table/Plot editor that you access by selecting the Table Editor button.

• skidpad -

• Entry Distance - Specifies the length of the straight path preceding the turn. Note that all paths are relative to the position of the vehicle at the end of the preceding mini-maneuver. If the preceding mini-maneuver was a skidpad and you want the vehicle to continue on the same circle in the current mini-maneuver, then specify zero (0) for Entry Distance.

• Radius - Specifies the radius of the skidpad.

• Turn Direction - Specifies which way the vehicle turns when traveling forward.

• straight - The vehicle travels forward from its current position along the tangent of the path from the preceding mini-maneuver. If the vehicle was under open-loop steering control in the preceding mini-maneuver, then the vehicle travels forward in the direction of its current velocity. You don't need to specify additional arguments.


Speed Contro You can select one of the following:

• ax_s_map

• ax_t_map

• file

• File Name - Enter the name of a file that contains the closed-loop data.

• lat_accel - Be sure to set Steer Control to skidpad.

• Lat. Acc. - Enter a value for the lateral acceleration.

• lon_accel

• Start Time

• Long. Acc - Enter a value for the longitudinal acceleration.

• maintain - The Driving Machine maintains the ending speed of the vehicle from the previous mini-maneuver. If this mini-maneuver is the first in the experiment, then the Driving Machine maintains the initial speed set in the EXPERIMENT block.

• Velocity

• speed_s_map

• speed_t_map

• vel_polynomial

• Velocity - Specifies the vehicle speed as polynomial of time. The Driving Machine computes the speed using the following relation:

IF (Time < START_TIME):SPEED = VELOCITYIF ( TIME START_TIME ):SPEED = VELOCITY +ACCELERATION*(TIME - START_TIME)+1/2*JERK*(TIME-START_TIME)**2

where START_TIME is the starting time relative to the beginning of the mini-maneuver.

Specify the following arguments:

VELOCITY = value <length/time> ACCELERATION = value <length/time2> JERK = value <length/time3> START_TIME = value <time>

Note that JERK is the time rate of change of acceleration. JERK = d(acceleration)/dt.

• Acceleration

• Jerk

• Start Time

You can use a Table/Plot editor to define the various maps of speed and acceleration expressed as a function of time or distance traveled.


306

SmartDriver Control Method

When you set Control Method to SmartDriver, you must also specify the Control Mode, the task, course file, as well as the maximum driving, braking, and turning accelerations.

Arguments

Specifying a Control Type

For any of the control signals (steering, throttle, braking, and so on), when you set Control Method to open, Adams/Car enables the Control Type option.

Arguments

Task Select one of the following:

• user_defined - Set your own vehicle limits.

• vehicle_limits - Use the maximum vehicle limits.

Course File Displays the name of a .xml or .drd file that describes the path over which the Driving Machine or Adams/SmartDriver drive the vehicle.

Select to choose a course file.

Max Driving Acc Enter the maximum driving acceleration index. Valid values are 0 to 100.

Max LH Turn Acc Enter the maximum left turn acceleration index. Valid values are 0 to 100.

Max Braking Acc Enter the maximum braking acceleration index. Valid values are 0 to 100.

Max Braking Acc Enter the maximum braking acceleration index. Valid values are 0 to 100.

Max RH Turn Acc Enter the maximum right turn acceleration index. Valid values are 0 to 100.

constant The Driving Machine inputs a constant signal to your vehicle model.

• Control Value - Enter a real number.

data_driven

Specifies that the control signal comes from a driver control data file (.dcd), which you specify. The Driving Machine opens the .dcd file and reads the appropriate data.

• Dcd Filename - Enter the name of a .dcd file.

data_map Lets you specifies a series of discrete values as a function of time. Click the Open Loop Demand Map button that appears to enter values and view a plot of the values you enter.

function Specifies that you should use any valid Adams/Solver function expression based on time.

• Function - Enter a time-based function. For example:

C20.0*SIN(2*PI*TIME)

where TIME is the simulation time.


impulse The Driving Machine outputs an impulse to your vehicle constructed from a pair of cubic step functions. To define the impulse, you must specify the following arguments:

• Start Time - The starting time of the impulse relative to the beginning of the mini-maneuver. For example, if the mini maneuver starts at 1.2 seconds simulation time and Start Time = 0.3 seconds, then the impulse begins at 1.5 seconds simulation time.

• Duration - The length in time of the impulse.

• Maximum Value - The height of the impulse. The impulse reaches its maximum value relative to the start time at half the duration.

Adams/Car computes the IMPULSE function as follows:

Let T1 = ( TIME - START_TIME ) / DURATION/2.0Let T2 = ( TIME - (START_TIME + DURATION/2.0) ) / DURATION/2.0IF ( T1 < 0.0 ):OUTPUT = 0.0IF ( 0 < T1 < 1.0 ):OUTPUT = MAXIMUM_VALUE * ( 3.0 - 2.0*T1)*T1*T1IF ( T1 > 1.0 and T2 < 1.0 )OUTPUT = MAXIMUM_VALUE( 1.0 - (3.0 -2.0*T2)*T2*T2 )IF ( T2 > 1.0 );OUTPUT = 0.0

The following plot illustrates the IMPULSE function:


308

ramp The Driving Machine supplies a ramp input. To define the ramp, you must supply the following arguments:

• Start Time

• Ramp Value

Adams/Car computes the RAMP function as follows:

If ( time < START_TIME ) input = INITIAL_VALUE if ( time > START_TIME ) then input = INITIAL_VALUE + ( time - START_VALUE) * RAMP_VALUE

Note: When using the RAMP function, the output value grows for the duration of the mini-maneuver.


sine The Driving Machine outputs a single-cycle sinusoid to your vehicle smoothed at the beginning and end by cubic-step functions. The duration of each cubic-step function is 1/100*CYCLE_LENGTH.

• Start Time - The starting time of the sinusoid relative to the beginning of the mini-maneuver. For example, if the mini-maneuver starts at 2.1 seconds simulation time and Start Time = 0.3 seconds, then the sinusoid begins at 2.4 seconds simulation time.

• Amplitude - The amplitude of the sinusoid.

• Cycle Length - The length of time to complete one cycle of the sinusoid.

Adams/Car computes the SINE function as follows:

Let T1 = (TIME - START_TIME) / CYCLE_LENGTH / 100.0 Let T2 = (TIME - (START_TIME + 0.99*CYCLE_LENGTH)) / CYCLE_LENGTH / 100.0IF ( T1 < 0.0 ):OUTPUT = INITIAL_VALUEIF ( 0 < T1 < 1.0 ):OUTPUT = INITIAL_VALUE + AMPLITUDE * SIN( 2.0*PI*(TIME - START_TIME)/ CYCLE_LENGTH) * (3.0 - 2.0*T1)*T1*T1IF ( T1 > 1.0 and T2 < 0.0 )OUTPUT = INITIAL_VALUE + AMPLITUDE * SIN( 2.0*PI*(TIME - START_TIME)/ CYCLE_LENGTH) IF ( T1 > 1.0 and 0.0 < T2 < 1.0 )OUTPUT = INITIAL_VALUE + AMPLITUDE * SIN( 2.0*PI*(TIME - START_TIME)/ CYCLE_LENGTH) (1.0 - (3.0 -2.0*T2)*T2*T2)IF ( T2 > 1.0:OUTPUT = INITIAL_VALUE

The following plot illustrates the SINE function:


310

step The Driving Machine inputs a STEP5 function to your vehicle model based on the following input parameters, which you must supply:

• Start Time

• Duration

• Final Value

Adams/Car computes the STEP function as follows:

If ( time < START_TIME ) then input = INITIAL_VALUE if ( START_TIME < time < START_TIME + DURATION ) then Let T = (TIME - START_TIME)/DURATION input = INITIAL_VALUE + ( FINAL_VALUE - INITIAL_VALUE)*( 3 - 2*T)*T**2 if ( time > START_TIME + DURATION ) then input = FINAL_VALUE

Note that START_TIME is relative to the beginning of the mini-maneuver.


Specifying a Control Mode

If you set Control Method to open, you must also define the Control Mode as either absolute or relative. If Control Method is not open, Control Mode is always absolute. With all open-loop maneuvers, the value of the preceding mini maneuver is used as the starting point for the next mini-maneuver. This is irrespective of whether you set Control Mode to relative or absolute. For example, your vehicle is driving on a skid pad at 30 mph, with 20o of steering wheel, when the first mini-maneuver is finished. The steering-wheel angle for the next mini maneuver will be 20o.

You can set Control Mode for the following open-loop control types:

• constant

• data_driven

• data_map

• step

swept_sine Sweeps the frequency of the output from the initial frequency to a maximum frequency at a given rate. Once the maximum frequency is achieved, the frequency remains constant. The amplitude of the swept sine function is fixed. To define swept sine, you must supply the following parameters:

• Start Time - The starting time of the function, measured from the beginning of the mini-maneuver.

• Amplitude - The amplitude of the swept-sine function.

• Initial Frequency - The starting frequency of the swept-sine function in <cycles/time>.

• Frequency Rate - The rate the frequency is swept from the initial frequency to the maximum frequency <cycles/time/time>.

• Max Frequency - The maximum frequency of the swept sine function in <cycles/time>.

The following plot illustrates the SWEPT_SINE open-loop function:


312

For these control types, Control Mode changes the meaning of the FINAL_VALUE input in the .xml. Control Mode has no effect on the rest of the Control Types, nor on machine, human, and SmartDriver control methods.

The relative and absolute methods allow you to define the steering-wheel angle for the end of the next mini maneuver.

Arguments

Here is another example. If at the beginning of the mini-maneuver the steering is 20o, the steering Control Method is set to open, the Control Type is set to step, and the FINAL_VALUE = 90.0, then FINAL_VALUE is relative to INITIAL_VALUE, and the steering angle at the end of the step input is

110o. If, however, Control Mode is set to Absolute, then the steering angle at the end of the step input

equals the FINAL_VALUE of 90o

Specifying Conditions

Conditions specify when one mini-maneuver ends so the next one can begin. For example, you might end a mini-maneuver when the vehicle speed reaches 100 kph. You can also group end conditions together. For example, you might end a mini-maneuver when the vehicle speed reaches 100 kph and the lateral acceleration exceeds 5 m/s2.

The event file supports conditions based on time, distance, velocity, acceleration, and many other vehicle control variables. Conditions reference a measure or solver variable by name to measure a given quantity in the model.

The Conditions tab of the Event Builder shows one possible condition at a time in Property Editor mode. To add conditions or view other defined conditions, click the button to the left of the condition name to enter Table Editor mode. In Table Editor mode, you can see all defined conditions, add new conditions, modify conditions, or delete conditions. The Table Editor mode also lets you see the full set of arguments available for each condition.

Absolute Indicates that the final value is absolute. For example, for a step input to the steering where the initial steering is 10 degrees and the final value is 50 degrees, the steer at the end of the step equals 50 degrees.

Relative Indicates that the final value is relative to the initial value. For example, for a step input to the steering where the initial steering is 10 degrees and the final value is 50 degrees, the steer at the end of the step equals 60 degrees.


Arguments

Then, the end condition is satisfied if:

5 - 0.1 < Lateral acceleration < 5 + 0.1

Name Filter Filters the listed conditions based on the substring you specify.

Name Shows the condition name (not editable).


314

Type Quantity that is measured. Can be:

• curvature - Curvature of the vehicle trajectory

• distance - Total distance traveled by the vehicle during a mini-maneuver

• engine_speed - Angular velocity of the engine crankshaft in number of revolutions per minute (rpm)

• lat_accel - Vehicle lateral acceleration

• lat_dis - Vehicle lateral displacement with respect to the global reference system

• lat_velocity - Vehicle lateral velocity

• loc_accel - Vehicle longitudinal acceleration

• lon_dis- Vehicle longitudinal displacement with respect to the global reference system.

• pitch_angle - Angular displacement about the vehicle's lateral axis

• pitch_rate - Time derivative of pitch angle

• rack_tra_vel - Time derivative of rack displacement

• rack_travel - Displacement in the steering rack joint

• radius - Radius of vehicle trajectory

• roll_angle - Angular displacement about the vehicle's longitudinal axis

• roll_rate - Time derivative of vehicle roll angle

• side_slip_ang - Angle between the ground-plane projections of the vehicle's longitudinal axis and its velocity vector

• stee_ang_vel - Time derivative of steering angle

• steering ang - Angular displacement in the steering-wheel joint

• time - Simulation time

• user_defined - Not implemented

• velocity - Vehicle longitudinal velocity

• vert_accel - Vertical acceleration of driver reference frame with respect to origo marker

• vert_dis - Vehicle vertical displacement with respect to the global reference system

• vert_velocity - Vehicle vertical velocity with respect to the global reference system

• yaw_accel - Angular acceleration about the vehicle's vertical axis

• yaw_angle - Angular displacement about the vehicle's vertical axis

• yaw_rate - Angular velocity about the vehicle's vertical axis


Referencing .dcd Files

You can reference driver control data (.dcd) files through XML event files to specify data for the method of control of the vehicle. When referencing .dcd files, event files can obtain two types of data:

• Open-loop data - Includes steering-wheel angle, throttle position, brake pressure, gear, and clutch position tabulated against time or distance traveled.

Test • == - Equal to trigger value

• >> - Greater than the trigger value

• << - Less than the trigger value

• |==| - Absolute type value is equal to the trigger value

• |<<| - Absolute type value is less than the trigger value

• |>>| - Absolute type value is greater than the trigger value

Trigger Value The value against which the measure is tested to determine if the end condition is satisfied. Except for ENGINE_SPEED, which uses RPMs, you must specify the value in modeling units as defined in the event file.

Error The allowed difference between measure and value that still satisfies the test. Error must be positive and be specified in modeling units as defined in the event file (except engine_speed, which is in RPMs). For example, if the cells of the table are:

Filter Time The test must be satisfied continuously over the filter time to satisfy the end condition. filter time must be positive.

Delay Time Once the end condition is satisfied, delay the end of the mini-maneuver by delay time.

Group Name You specify a name to group conditions together. All conditions having the same group name must be satisfied simultaneously to end a mini-maneuver. For example, you might specify two end conditions:

• Longitudinal velocity equal to 20 m/s

• Lateral acceleration greater than 5 m/s/s Then you place the specified end conditions in the group mygroup. To end the mini-maneuver, the longitudinal velocity must be 20 m/s and the lateral acceleration must be greater than 5 m/s/s.

Condition Type Select a condition type:

• abort - When met, it causes the simulation to stop.

• end - When met, it causes the simulation to proceed to the next mini-maneuver, if one is defined.

• info - Not yet implemented

• warning - Not yet implemented


316

• Closed-loop data - Uses data from the dcd file to fix the vehicle path and speed for a mini-maneuver. Examples of closed-loop data are the vehicle position {x, y} versus time (t) or path {x, y} versus distance traveled (s). Closed-loop data can also include vehicle speed and lateral acceleration which the Machine Control integrates to determine the desired vehicle path and speed.

You reference .dcd files in your event files by selecting Machine for Steering/Throttle and Braking and browsing your databases for dcd files in the File Name text box. That is, using the file option for Machine Control means that you want to obtain control data from a .dcd file.

Example Event Files

In Adams/Car, XML became the default file format for Driving Machine analyses. Although Adams/Car still supports driver control files (.dcf), it now automatically converts them to .xml. The .xml files are referred to as event files. Although the contents of the two files types look different, they contain the same event information. You work with .xml files through the Event Builder.

In the shared Adams/Car database, we provide files in both .dcf and .xml format. These files are stored in the driver_controls.tbl directory/table.

Adams/SmartDriver AnalysisThe Adams/SmartDriver analysis lets you run an analysis described in an existing event file (.xml). You can drive the vehicle at the acceleration limits or some percentage of those limits.

To set up an Adams/SmartDriver analysis:

1. From the Simulate menu, point to Full-Vehicle Analysis, and then select Adams/SmartDriver.

2. Press F1 and then follow the instructions in the dialog box help for Full-Vehicle Analysis: SmartDriver.

3. Select OK.

317Running AnalysesUsing the Driving Machine

Using the Driving MachineYou use the Driving Machine to perform full-vehicle analyses. The Driving Machine drives your virtual vehicle according to your instructions much like a test driver would drive an actual vehicle. The Driving Machine steers the vehicle, applies the throttle and brake, and shifts gears (using the clutch). You can instruct the Driving Machine to switch between open- and closed-loop (Machine Control and SmartDriver) control during a simulation.

Using open-loop control, the Driving Machine can, for example, input a swept-sinusoid to the steering or play back recorded steering, throttle, brake, gear, and clutch signals as input to your virtual vehicle. This lets you use data acquired in real tests as input to your virtual vehicle.

Using Machine Control, which replaced DriverLite, the Driving Machine can, for example, steer a vehicle around a skid-pad, while gradually increasing speed. You use Machine Control to have the vehicle follow a path and maintain a specified longitudinal speed or acceleration. Inputs to Machine Control are the target path the vehicle should follow and/or a target speed or longitudinal acceleration vs time or distance.

Using Adams/SmartDriver, you can determine the maximum performance of a vehicle as it follows a specified path. Adams/SmartDriver is an extra-cost, add-on product that lets you specify a desired performance criterion (for example, 100%, 80%, 50% of vehicle limits) for the vehicle as it follows the defined path. Adams/SmartDriver then creates a target longitudinal speed along the path that meets the desired performance criterion.

Adams/Car stores your instructions to the Driving Machine in an XML event file. You can use the Event Builder (or any text editor) to create or modify an event file.

Driving Machine reads recorded open-loop signals and vehicle path and velocity data from text files named driver control data files (.dcd).

To help you calculate the control signals, Adams/Solver passes vehicle information such as position, velocity, and acceleration, to the Driving Machine. The Driving Machine provides a means for defining and passing sets of command signals, feedback signals, and parameters for each of the five control signals (steering, throttle, brake, gear, and clutch).

Note: We changed the Driving Machine architecture to support XML files as the default, while maintaining support for legacy dcf files. If you specify a dcf file, Driving Machine automatically converts it to an XML file in the working directory so you can use the Event Builder to review and modify the event.

Adams/CarUsing the Driving Machine

318

The following figure shows how the Driving Machine works in a virtual prototyping model.

Learn more about the Driving Machine:

• What You Can Do with the Driving Machine

• How You Benefit from Using the Driving Machine

• Steps in Using the Driving Machine

• Creating Paths for Driving Machine

• Data Flow in Driving Machine

• Template Updates

• Limitations to the Driving Machine


What You Can Do with the Driving MachineUsing the Driving Machine, you can:

• Input the vehicle path {x, y} and speed, and use closed-loop, Machine Control, to steer a vehicle along a path or follow a desired velocity or both (the table, Closed-Loop Data in .dcd Files, lists all potential inputs).

• Input a variety of open-loop functions, such as swept-sine and impulse, to the steering, throttle, or brake.

• Input recorded steering, throttle, brake, gear, and clutch signal to your model.

• Stop a simulation, switch controllers, and change output-step size based on reaching a target lateral acceleration, longitudinal velocity, or distance traveled.

• With the optional Adams/SmartDriver closed-loop control, you can specify a desired vehicle performance level, such as 100% or 50%, and input a path and speed as you would for Machine Control.

How You Benefit from Using the Driving MachineWhen working with the Driving Machine, you have the following benefits:

• You save the time you previously needed to set proper gains for closed-loop controllers. The Driving Machine incorporates proprietary control algorithms from MSC.Software.

• You shorten simulation times by ending simulations based on targets for lateral acceleration, longitudinal velocity, and distance traveled.

• You gain flexibility in how you input vehicle paths and desired velocity profiles, choosing from recorded data stored in external files or parametrically generated paths and profiles based on a few simple inputs.

Steps in Using the Driving MachineFollow these steps to use the Driving Machine:

1. Assemble a full-vehicle model with the .__MDI_SDI_TESTRIG test rig or open an existing full-vehicle assembly.

2. Do either of the following:

• Use a predefined analysis (from the Simulate menu, point to Full-Vehicle Analysis, and then point and select the predefined analysis you want).

• Create your own event file to perform your specific set of simulations (from the Simulate menu, point to Full-Vehicle Analysis, and then select Event Builder).


320

Tips on Creating Paths for Driving Machine

Applies to Machine Control and SmartDriver

The following are tips for creating paths for the Driving Machine.

Remove Excess Noise

The path referenced in the event file is the TARGET path used by the steering controller with no smoothing or other manipulation to alter the path shape. Therefore, any irregularities included in the path description, such as the noise coming from telemetry data, are seen by the steering controller and can produce a quickly changing steering input. Further, because the Driving Machine computes the steering input at discrete time steps (equal to the selected output step), and the steering input is typically applied through a MOTION on the steering wheel, a quickly changing steering input will produce a noisy steering torque signal. Therefore, to minimize noise in the steering torque you may want to preprocess the path data to remove noise and/or add corner cutting, and then store the resulting path in a .dcd file.

Path Point Spacing Important

In addition, path points spaced too far apart can also produce a noisy steering torque. To obtain the best results from the controller with the lowest level of noise, we recommend that the largest distance between points in the path be less than the minimum distance traveled by the vehicle in one output step. That is, the distance travelled between two consecutive output steps should be greater than the distance between any two path points. For example, if the maneuver minimum velocity is 10 m/s and the recommended time step size is used (0.01 seconds), the suggested path point spacing is 0.1 meter. We recommend that you create your paths for the lowest speed you expect to run, because small path point spacing is suitable for both low- and high-speed events.

Also, note that if the distance between path points is greater than 0.5 meters, the controller re-samples the path to a path point spacing of 0.5 meters. (This is the current default. You can use an API to modify this setting.)

The following plots show the effect on steering input and steering torque using path point spacings of 0.5 m and 0.05 m at low and high speed:

• Figure 1 - Path following at low speed (around 5 m/s, output step size 0.01 seconds)

• Figure 2 - Path following at standard speed (from 20 to 40 m/s, output step size 0.01 seconds)


Low Speed Test

Standard-speed Test

When speed increases, the difference in path point spacing has no effect.


322

Data Flow in Driving MachineWhen you submit a simulation using the Driving Machine, Adams/Car generates an Adams/Solver command file (.acf), an Adams/Solver dataset file (.adm), and an XML event file. The .acf file instructs Adams/Car Solver to read the dataset file and event file (using abgVDM::EventInit CONSUB). It also instructs Adams/Car Solver to perform maneuvers described in the event file (using abgVDM::EventRunAll CONSUB). Adams/Car Solver then provides the standard output files: .msg, .res, .gra, and .out.

The event file (.xml) describes the maneuver you want to perform as a list of mini-maneuvers. The event file can reference one or more driver control data (.dcd) files. Driver control data files contain either closed-loop or open-loop data. An example of closed-loop data is vehicle path and speed (the table, Closed-Loop Data in .dcd Files, lists all potential inputs). Open-loop data are steering, throttle, brake, gear, and/or clutch signals versus time.

The following figure summarizes the data flow specific to the Driving Machine.

Template UpdatesThe 2005 Driving Machine employs vehicle controllers developed by MSC.Software, commonly known as Machine Control, which replaces DriverLite functionality, and Adams/SmartDriver. To better control


speed and path, the 2005 Driving Machine needs additional information about the vehicle. In particular, the speed controller uses a feed-forward function to ensure quick and accurate response. However, this requires information about the available engine brake torque, engine drive torque, brake torque, and aerodynamic drag. You supply this information by creating new output communicators in your templates. In addition, you must also enter vehicle parameter data, such as overall steering ratio that is stored in the assembly file.

For more information, see Working with Templates->Template Updates.

Limitations of the Driving MachineThe Driving Machine has the following limitations:

• It can only accurately steer a vehicle when positive steer inputs steer the vehicle to the left.

• It can only drive the vehicle within the vehicle's limits of lateral and longitudinal acceleration, and longitudinal velocity.

Working with Driver Control Data Files (.dcd)You use driver control data (.dcd) files to specify:

• The closed-loop data, such as path and speed you want a vehicle to follow.

• The open-loop data, which is the steering, throttle, brake, gear, and clutch signals versus time you want to input to a vehicle.

To use a .dcd file, you must reference it from an event file (.xml).

Driver control data files contain data for use by the Driving Machine. To instruct the Driving Machine to use the data from a .dcd file, you must reference the file in an event file (.xml). An excerpt from a .xml showing a reference to a .dcd file looks like the following:

(STEERING) METHOD = 'OPEN'CONTROL_TYPE = 'DATA_DRIVEN'FILE_NAME = 'my_data.dcd'

Driver control data files hold two types of data:

• Open-loop data - Data that is played back as input to the vehicle without concern for how fast or where the vehicle goes. Such data includes: steering-wheel angle, throttle, brake, gear, and clutch signals. Examples of open-loop data include steering-wheel angle versus time, and throttle position versus time.

• Closed-loop data - Data that specifies exactly where and how fast the vehicle should go. An example of closed-loop data is vehicle x and y position versus time. You can specify closed-loop data in several forms. For example, curvature and velocity versus distance traveled, or lateral acceleration and longitudinal acceleration versus time. You specify the type of data using the SPEED_CONTROL and STEERING_CONTROL arguments in the .dcd file.


324

Learn about .dcd files:

• Structure of .dcd Files

• Specifying Closed-Loop Data

• Creating .dcd Files

• Example .dcd File

Structure of Event Files

Event files contain the following type of information:

• Name of Event File

• Speed

• Gear Number

• Static Setup

• Gear Shifting Parameters

• Mini-Maneuvers for the Experiment

Name of Event File

When you assign a name to the event file, Adams/Car automatically generates a file with extension .xml in the working directory and updates the Event File text box with the file name you entered.

Speed

Represents the initial vehicle speed for the maneuver.

Gear Number

Represents the initial gear position for the maneuver.

Static Setup

You can specify static-setup analyses that remove start-up transients that can eliminate mini-maneuvers that you might normally use to set up a vehicle for cornering maneuvers. For example, in the past, to perform a brake-in-turn analysis you might have run a transient mini-maneuver to have the vehicle turn-in and reach static-setup on given turn, at a given speed/lateral acceleration, before starting to brake the vehicle. This approach is equivalent to a test driver on a proving ground, driving at a steady speed and in a steady-state condition (vehicle has no transients) before starting a dynamic maneuver (braking, acceleration, steering, and so on). Now you can perform a much faster (less CPU time) static-setup analysis.

You can set static setup to any of the arguments described next.


Arguments

none Adams/Car does not perform a static equilibrium analysis. Rather, it locks the wheel rotations and then performs an acceleration initial-conditions analysis, which initializes Adams/Tire. Adams/Car then deactivates the wheel lock joint primitives before executing the first mini-maneuver.

normal Locks the wheel rotations using joint primitives, but leaves the body free to move in the fore-aft, lateral, and yaw directions. Soft springs (1 N/m and 10 N m/radian), introduced by Adams/Tire just for static equilibrium, acting in all directions between each wheel center and ground limit, but do not prevent, body yaw, fore-aft, and lateral displacements. Then, before executing the first mini-maneuver, Adams/Car deactivates the joint primitives to unlock the wheel rotations, and Adams/Tire removes the soft springs.

The transitional and torsional stiffnesses supplied by the tire act in all directions (x,y,z). Without these stiffnesses, the vehicle would have a neutral equilibrium position in the x-y plane of the road.

Note that Adams/Chassis does not support normal.

settle Locks the body's fore-aft, lateral, and yaw displacement using joint primitives and performs a static equilibrium to settle the vehicle on the road. Then, before executing the first mini-maneuver, Adams/Car deactivates the joint primitives.

For example selecting settle and specifying an initial velocity of 27777.78 mm/s is equivalent to driving a stake vertically through the vehicle body and constraining the body to move vertically about the stake. It allows the vehicle to roll (cornering) and pitch (braking), but does not allow rotation about the axis of the stake (Yaw). When the vehicle is released from this condition, it should be relatively well balanced to remove initial transient effects. An imbalance in the tire forces could, however, cause a slight steering effect. If you want to remove this effect, we recommend that you use straight.


326

Gear-Shifting Parameters

Define the gear-shifting properties and the shape of the upshift and downshift curves for throttle and clutch signals.

Arguments

skidpad Locks the body's fore-aft and lateral position using a joint primitive. Adams/Car adjusts the steering and throttle so the vehicle's yaw rate, lateral acceleration, and speed match those prescribed by the initial radius, initial turn direction, and the initial lateral acceleration or initial speed. You must specify the initial radius and turn direction. Also, you must supply either the initial lateral acceleration or the initial speed.

For example, selecting skidpad and specifying an initial radius, turn direction, and initial speed effectively performs a settle static setup followed by a straight static setup. Then, Adams/Car adjusts the steering and throttle so that the vehicle's yaw rate, lateral acceleration, and speed match those prescribed in the event file. By carefully observing the .msg file Adams/Solver produces, you can see the model manipulation occur.

straight Locks the body's fore-aft and lateral position using a joint primitive. Adams/Car adjusts the steering (so that the vehicle's yaw rate and lateral acceleration are zero) and the throttle and/or brake (to balance any aerodynamic drag and scrub that the tires produce and to match the specified initial longitudinal acceleration). Then, before executing the first mini-maneuver, Adams/Car deactivates the joint primitives.

The maneuver has two separate static analyses: the first uses the settle method, the second uses a force balance on the vehicle body to ensure that the net lateral force is negative (the vehicle is traveling in a straight line) and that longitudinal forces are zero. The values for steering-wheel angle, throttle position, and so on, are used as initial conditions for the subsequent dynamic analysis.

Throttle Fall Time Delta time of the step function for the descending curve of the throttle signal (> 0.0)

Clutch Fall Time Delta time of the step function for the descending curve of the clutch signal (> 0.0)

Throttle Raise Time Delta time of the step function for the ascending curve of the throttle signal (> 0.0)

Clutch Raise Time Delta time of the step function for the ascending curve of the clutch signal (> 0.0)


Mini-Maneuvers

The Driving Machine runs each mini-maneuver in the order listed, until the list is ended or a mini-maneuver is terminated.

For each mini maneuver, you must specify a name for the mini-maneuver, the control signals (steering, throttle, braking, gear, and clutch), as well as the condition for ending the mini maneuver. Learn more about Creating Mini-Maneuvers.

Structure of .dcd Files

Driver control data (.dcd) files use a TeimOrbit File Format similar to other Adams/Car property files. Driver control data files must contain these data blocks:

• MDI_HEADER block - Identifies the file as a .dcd file and provides version information.

• UNITS block - Identifies the units of the data contained in the .dcd file.

The driver control data file must also contain at least one of two data blocks:

• OPEN_LOOP block - Specifies the steering, throttle, brake, gear, and clutch inputs to the vehicle.

• CLOSED_LOOP block - Specifies the path or the speed of the vehicle, or both.

The following is an example .dcd file:

[MDI_HEADER]FILE_NAME = iso_lane_change.dcdFILE_TYPE = 'dcd'FILE_VERSION = 1.0FILE_FORMAT = 'ASCII'

(COMMENTS){comment_string}

'Example .dcd file containing steering path for iso lane change'

[UNITS]LENGTH = 'meters'FORCE = 'newton'MASS = 'kg'TIME = 'sec'ANGLE = 'radians'[CLOSED_LOOP]STEERING_CONTROL = 'path'SPEED_CONTROL = 'none'

Shift Time Duration of the gear shifting event (> 0.0)

RPM Control Enables an algorithm for RPM limiting during gear shifting

Note: Driver control data files can contain both open-loop and closed-loop blocks.


328

(DATA){ X Y }0.0 0.000-45.0 0.000 -52.5 0.00060.0 0.00090.0 3.586 -102.0 3.586-115.0 3.586 -140.0 0.172-147.0 0.172 -155.0 0.172-162.0 0.172 -170.0 0.172 -200.0 0.172-300.0 0.172

[OPEN_LOOP]ORDINAL = 'time'

(DATA){ time steering throttle brake gear clutch }0.0000E-01 0.1465E-02 0.3016E-02 0.0000E+00 0.3000E+01 0.0000E+000.1000E-01 0.1465E-02 0.3016E-02 0.0000E+00 0.3000E+01 0.0000E+00 0.2000E-01 0.1541E-02 0.3193E-02 0.0000E+00 0.3000E+01 0.0000E+000.3000E-01 0.1633E-02 0.3748E-02 0.0000E+00 0.3000E+01 0.0000E+000.4000E-01 0.1730E-02 0.5697E-02 0.0000E+00 0.3000E+01 0.0000E+000.5000E-01 0.1865E-02 0.1197E-01 0.0000E+00 0.3000E+01 0.0000E+000.6000E-01 0.1959E-02 0.2062E-01 0.0000E+00 0.3000E+01 0.0000E+000.7000E-01 0.2108E-02 0.4782E-01 0.0000E+00 0.3000E+01 0.0000E+000.8000E-01 0.2190E-02 0.8150E-01 0.0000E+00 0.3000E+01 0.0000E+000.9000E-01 0.2180E-02 0.1329E+00 0.0000E+00 0.3000E+01 0.0000E+000.1000E+00 0.2011E-02 0.2006E+00 0.0000E+00 0.3000E+01 0.0000E+00

Specifying Closed-Loop Data

When reading the following specification you should observe the following rules:

• [ ] = Data block

• ( ) = Sub-block

• { } = Data header

• || = Options, and means OR

• && = And

The nomenclature is:

• lon_vel = Vehicle longitudinal velocity

• lon_acc = Vehicle longitudinal acceleration

• lat_acc = Vehicle lateral acceleration


• distance = Arc-length or distance traveled along the path

• curvature, k=1/radius

• x = X position of vehicle relative to ISO-Earth Axis System

• y = Y position of vehicle relative to ISO-Earth Axis System

• { } = Set of inputs

The following table summarizes the closed-loop data that a .dcd file can contain:

• The columns represent speed-control options from the driver parameters array.

• The rows represent the steering control options from the driver parameters array.

• The intersections give the data contained in the .dcd file and, therefore, the data input to the funnel to produce {x, y, lon_vel} as needed by Driving Machine.

• p1 refers to the first parameter in the steering and throttle (speed) driver parameters arrays (initial conditions arrays) in the dataset Adams/Car outputs.

Closed-Loop Data in .dcd Files

Creating .dcd Files

You can use the sample .dcd files that we provide or you can create your own .dcd files.

To create .dcd files:

1. You can use one of three methods to create .dcd files:

• Run a physical or virtual test and record the data that you obtain from the five actuator application areas.

• In a text editor, modify the sample .dcd files that we provide for you.

• Create a .dcd file using a text editor and following the specifications and format shown in Specifying Closed-Loop Data and Example .dcd File Architecture.

2. Save the file and reference it when running File-Driven Analyses.

SPEED_CONTROL STEERING_CONTROL none lon_vel (p1=0) lon_acc (p1=1) lat_acc (p1=2)

path (p1=3)

none NOT VALID

{(distance or time), lon_vel}

{(distance or time), lon_acc}

NOT VALID NOT VALID

curvature (p1 = 0) {distance, curvature}

{(distance or time), curvature, lon_vel}

{(distance or time), curvature, lon_acc}

{(distance or time), curvature, lat_acc}

NOT VALID

path (p1 = 1) {x, y} {x, y, lon_vel} {x, y, lon_acc} {x, y, lat_acc} {x, y, time}

lat_acc (p1 = 2) NOT VALID

{distance or time, lat_acc, lon_vel}

{distance or time, lat_acc, lon_acc}

NOT VALID NOT VALID


330

Example .dcd File

The following shows the architecture of a .dcd file and all the options you can set for a .dcd file. It contains options, logic, and general rules that you must follow when creating a .dcd file.

[MDI_HEADER]FILE_NAME = filename.dcdFILE_TYPE = 'dcd'FILE_VERSION = 1.0 FILE_FORMAT = 'ASCII'

(COMMENTS){comment_string}'Any comment'

[UNITS] LENGTH = 'meter' || 'millimeter' || 'centimeter' || 'kilometer' || etc.FORCE = 'newton' || 'kilogram_force' || etc.ANGLE = 'deg' MASS = 'kg'TIME = 'sec'

[CLOSED_LOOP]comment = stringsteering_control = 'none' || 'curvature' || 'path' || 'lat_acc' speed_control = 'none' || 'lon_vel' || 'lon_acc' || 'lat_acc' || 'path'ordinal = 'distance' || 'time' lon_vel_max = floatlon_vel_min = float lon_acc_max = float lon_acc_min = float lat_acc_max = float lat_acc_min = float

(DATA) $ steering, speed$ 1 Case{none, none} -- null case, no data required!!$ 2 Case{none, lon_vel}$ 3 Case{none, lon_acc} $ 4 Case{none, lat_acc} -- NOT VALID$ 5 Case{none, path} -- NOT VALID { ( distance || time ) && ( lon_vel || lon_acc ) }

$ 6 Case{curvature, none} -- Must have distance with curvature{ distance && curvature }

$ 7 Case{curvature, lon_vel}$ 8 Case{curvature, lon_acc}$ 9 Case{curvature, lat_acc} $10 Case{curvature, path} -- NOT VALID{ ( distance || time ) && curvature && ( lon_vel || lon_acc || lat_acc )}

$11 Case{path, none}$12 Case{path, lon_vel}$13 Case{path, lon_acc} $14 Case{path, lat_acc} { x && y && ( lon_vel || lon_acc || lat_acc ) }

$15 Case{path, path}{ x && y && time }

$16 Case{lat_acc, none} -- NOT VALID$17 Case{lat_acc, lon_vel}$18 Case{lat_acc, lon_acc}$19 Case{lat_acc, lat_acc} -- NOT VALID $20 Case{lat_acc, path} -- NOT VALID{ ( distance || time ) && lat_acc && ( lon_vel || lat_acc ) }

[OPEN_LOOP]ordinal = 'time' || 'distance'{distance || time steering throttle brake gear clutch}*

0.0 0.0 0.0 0.0 2 0.0


0.1 0.0 0.0 0.0 2 0.0

*You can select distance or time and any combination of steering, throttle, brake, gear, and clutch.

Example corresponding to $ 2 Case{none,lon_vel}:.....[CLOSED_LOOP]STEERING_CONTROL = 'NONE'SPEED_CONTROL = 'LON_VEL'ORDINAL = 'TIME'(DATA){ TIME, LON_VEL }0.0 27.7770.1 27.7770.2 27.7760.3 27.7750.4 27.774 0.5 27.773.....

Example corresponding to $ 7 Case{curvature,lon_vel}:.....

[CLOSED_LOOP]STEERING_CONTROL = 'CURVATURE'SPEED_CONTROL = 'LON_VEL'ORDINAL = 'DISTANCE' (DATA){ DISTANCE, CURVATURE, LON_VEL }0.0 0.000 27.7771.0 0.002 27.7772.0 0.004 27.7773.0 0.006 27.7764.0 0.008 27.7755.0 0.010 27.7746.0 0.010 27.7737.0 0.010 27.7748.0 0.010 27.7749.0 0.010 27.774 10.0 0.010 27.77411.0 0.010 27.77412.0 0.010 27.77413.0 0.010 27.774

Machine Control BasicsMachine Control is a vehicle controller that you can use to simulate the control actions of a driver. You simulate the actions of a driver by operating the steering, pedals, and gears of a simulated vehicle.

Machine Control determines control actions such that a simulated vehicle can follow a specified path along a 2D or 3D road, while simultaneously following a specified longitudinal velocity or acceleration. Machine Control's control action combines a reference trajectory planner and a model-predictive controller (MPC), sometimes known as a feed-forward plus feedback controller.


332

At the trajectory planning stage, your targets for the vehicle and driver behavior and some basic parameters describing the characteristics of the simulated vehicle are taken into account, and a realistic trajectory that most closely satisfies your targets is identified (for example, path, speed, and acceleration).

Machine Control uses simple mathematical models of vehicle dynamics, such as a bicycle model, a particle model, and a kinematic drivetrain model, to estimate the necessary control actions, such as the steering angle and throttle position. Machine Control applies these estimated controls as inputs to the simulated vehicle in a feed-forward manner, such that approximately correct control actions are applied without delay.

Differences between the behavior of the simulated vehicle and the expected behavior (that is, the behavior of the idealized models employed by the controller) are corrected continuously using feedback controllers, which adjust the control actions to minimize the error between the reference trajectory and the actual vehicle behavior.

Learn more about Machine Control:

• Feed-Forward Control

• Trajectory Planning

• Feedback Control

• Computation of Controls

Feed-Forward Control

Feed-Forward Lateral Control

Global axes, x-y, local axes, X-Y,


vehicle path and global yaw angle,

The projection of the vehicle path onto the ground plane is related to the velocities and global heading

as:

where:

The feed-forward component of the lateral control action is computed by assuming that your simulated vehicle responds as a bicycle model. The simplicity of the bicycle model allows the analytical identification of the relationship between the geometry of the path and the necessary control action (steering angle), and vice-versa.

In a bicycle model, the lateral forces from both tires on an axle are assumed to act in the same direction, and the left and right steer angles are assumed to be the same. In other words, Ackerman steering geometry is not considered. With these assumptions, the tires may be lumped together into a single tire representation, and the model is guided by a single steer angle.

( ) Global position of the vehicle

(VX, VY) Velocities of the vehicle relative to vehicle-fixed axes

Global heading of the vehicle

x· VX cos VY sin–=

y· VX sin VY cos–=


334

This simplified model is used to identify the necessary steer angle required for the vehicle to follow the connecting contour.

Simplification of a vehicle to the bicycle model

The form of the bicycle model employed by Machine Control assumes pure rolling of the front and rear tires with no kinematic or compliance-steer effects, and therefore, no lateral velocity at the rear axle. Note that this does not imply zero sideslip at the center of mass.


If the origin of the vehicle-fixed local axis system shown above is selected to be the center of the rear axle (not the center of mass), then the lateral velocity VY is now always assumed to be zero, and the

assumed path of the vehicle simplifies to:

where:

In this case, the center of the turn always lies on a line through the rear axle. The steer angle required to yield a certain path curvature is then always equal to the Ackerman angle, and is independent of the vehicle speed VX:

where:

and, therefore, this single steer angle input to the bicycle model controls the radius of turn and the curvature of the path. A simple inversion of this equation enables an estimate of the necessary steer angle to be calculated and applied to the simulated vehicle in a feed-forward sense.

Feed-Forward Longitudinal Control

To control either the velocity or acceleration of the simulated vehicle such that they match the reference, a particle model, a simple aerodynamic drag model, and a kinematic drivetrain model are used to predict the relationship between the wheel torque and the acceleration response of the vehicle.

The force or torque required to accelerate or decelerate the vehicle is expressed as a wheel torque, that the engine and brakes must apply to one or more wheels. The magnitude of the required torque is computed from the vehicle drag, inertia and tire rolling resistance:

Rate of change of the direction of the path at the rear axle (note that this is not equal to the yaw rate of the vehicle).

E Wheelbase of the vehicle

R Radius of the turn at the rear axle

Curvature of the path of the rear axle


336

Tw = Tinertial + Taero-drag+ Trolling-resistance

where:

where:

Gear Shifting

Gear shifts are triggered on the basis of engine speed thresholds, and the gear is incremented according to the following strategy:

Tw Total net wheel torque required to follow the reference

Tinertial Component that is required to accelerate the vehicle inertia

Taero-drag Required to overcome aerodynamic resistance

me Mass of the vehicle

aref Target (reference) vehicle acceleration

Vref Target (reference) vehicle speed

Req Average rolling radius of the wheels

Density of air

CD Nominal drag coefficient of the vehicle

A Frontal area of the vehicle

Tinertial me

Vref

t------------- Req me aref Req = =

Taero drag–12---ACDAV

2refReq=

A


where:

Trajectory Planning

Connecting Contour

For the lateral control of the vehicle, a simple model of the vehicle (a bicycle model) is used to compute the control action that should cause the vehicle to follow the intended path. The simulated vehicle, however, may not exactly follow the target path because of differences between the simplified model and the simulated vehicle, or external factors (road roughness and aerodynamic disturbances).

Therefore, the potential for offset between the instantaneous vehicle location and heading, and the location and heading of the path must be considered. In considering the location and heading of the path, Machine Control builds a connecting contour between the current vehicle position (wherever it may be) and some point on the target path, along which the vehicle will be steered to later bring it back to the target path:

Figure 16 Connecting contour

g Current gear selection

g' Revised gear selection

w min Minimum engine speed allowed before a downshift is triggered

w max Maximum engine speed allowed before an up-shift is triggered

g min Highest available gear, or the number of available gears

Note: Driving Machine will not shift into neutral.


338

The function that describes the connecting contour is parameterized such that one end of the connecting contour matches the position and direction of the vehicle (at the vehicle rear axle) and the other end of the connecting contour matches the path (at the preview distance, where the contour connects with the target path), as shown in the above figure.

The connecting contour then becomes the reference trajectory (path) for the lateral control of the vehicle, and the vehicle is steered by both feed-forward and feedback controllers, such that it should follow this connecting contour. The connecting contour is updated each time the Machine Control controller is called.

Longitudinal Trajectory Planning

The longitudinal trajectory planning essentially consists of constructing either a target velocity against distance traveled along the track centerline, or a target acceleration against distance traveled, according to your description of the target (for example, acceleration against distance traveled, velocity against time).

Feedback Control

Yaw Rate Feedback

The yaw rate feedback component of the controller corrects for the difference between the yaw rate response of the simulated vehicle and that of the bicycle model. Errors between the yaw rate reference and the yaw rate of the simulated vehicle are quickly corrected, such that the simulated vehicle follows the intended trajectory as closely as possible, even if the feed-forward control identified from the bicycle model is significantly in error.

The yaw rate error is determined by considering the curvature that would result if the current yaw rate were a steady-state value, and is corrected using a feedback controller, whose output is also fed into the steering angle.

Lateral Displacement Feedback

The connecting contour approach does not include any term to correct for steady-state lateral displacement error. This is preferred in most situations, because the resulting control actions tend to be more realistic and robustly stable. Once the vehicle is close to the target path, an additional controller acting on the distance Lo (the offset of the projected vehicle centerline from the path) adjusts the lateral displacement of the vehicle:

where is a flag indicating whether the lateral displacement controller is activated, that is whether the lateral displacement error Lo is small:


Note that in the above, positive Lo indicates a vehicle to the left of the target path, requiring a positive

steering correction.

Longitudinal Velocity Feedback

Errors in longitudinal velocity are compensated using a PID controller:

where the velocity error is:

Ve = Vref(s) - Vactual

where:

Anti-windup

To improve the stability of the control in conditions of actuator (usually engine torque) saturation, the input to the integral term of the controller is set to zero. This prevents wind-up of the integral term when the vehicle is unable to provide any more torque, such that the feedback component of the torque demand becomes:

where aw = 0 when saturation of the available torque is detected, aw = 1 otherwise.

s Distance along the reference path

Vref(s) Reference velocity

Vactual = Vx Longitudinal component of the vehicle velocity


340

Computation of Controls

Summation of Feed-Forward and Feedback Terms

Simple summation of the feed-forward and feedback terms gives the total demand from the lateral and longitudinal controllers (steer angle and net wheel torque):

Mapping Net Wheel Torque Demand to Control Actions

Once the required total net wheel torque, Tw has been estimated, basic knowledge of the brake system

and driveline are used to identify the necessary control actions (throttle and brake) that must be applied, such that the vehicle delivers the required net wheel torque.

The range of available net wheel torque is related to the available engine torque and the gearing of the vehicle. Neglecting driveline inertia, the ratio of the gearbox and the differential defines the relationship between the net wheel torque (Tw), and the engine torque (Te), at any instant:

such that the upper and lower limits Tm and TM on the net wheel torque, Tw (we) can be identified from

the upper and lower limits on Te (we):

where:

The maximum brake torque, TB, is assumed to be constant.

we Current engine speed (supplied as an input to Machine Control)

Minimum engine output torque (from the user engine map)

Maximum engine output torque (from the user engine map)

Rd Mean differential (final drive) ratio (from the basic vehicle knowledge)

Rg Gearbox ratio (from the basic vehicle knowledge)


Net wheel torque limits as a function of engine speed, and maximum brake torque

The above figure shows the user-supplied engine model, scaled according to the gearing of the vehicle, to yield:

• The maximum available net wheel torque, TM (normally positive for all we)

• The minimum available net wheel torque Tm (usually negative, especially at high engine speed

we, since it includes frictional and pumping losses due to throttling).

To define these limits, you can do either of the following:

• Supply a detailed nonlinear engine map, relating throttle to engine torque,

(therefore, adding a third dimension to the figure above)

• Supply only the maximum and minimum engine torques,

and choose Machine Control to employ a linear model of throttle response:


342

or

If a throttle map is provided, then this is mathematically inverted, so that the necessary throttle position can be identified from the required net wheel torque Tw, provided it is feasible for the engine to deliver

this torque at the current engine speed :


If the linear model is selected, then the feed-forward throttle and brake signals can be determined directly from the required torque:

Control Modulation During Gearshift and Wheel-lift Events

Throttle and clutch modulation during gear-shifting

During a gear-change, the control actuation is open-loop, except for the optional closed-loop rpm control as the clutch is re-engaged. In the following plots, which show the form of the control actions, the origin of the time base is set to be the instant of triggering the gearshift event (see Gear Shifting).

The action of the clutch is determined, and the throttle signal, computed by the feedback and feed-forward controllers, is modulated according to the following parameters:


344

• Gear change time (not the time of the whole event, but the time for which the clutch is not fully engaged)

• Clutch raise and fall time

• Throttle raise and fall time

• DT1 (the delay between clutch disengagement and throttle release)

• DT2 (the delay between that start of clutch re-engagement and start of throttle reapplication)

The following plot shows the influence of the parameters DT1 and DT2:


The following plot shows the influence of the throttle raise and fall time parameters:


346

The following plots show the effect of changing a single parameter from this baseline:


• Changing clutch raise time:


348

• Changing clutch fall time:


• Changing throttle raise time:


350

• Changing throttle fall time:


• Changing DT1:


352

• Changing DT2:

RPM control during clutch re-engagement

During a gear change, between the time when the new gear is selected and the clutch is fully engaged, the engine RPM we can optionally be controlled in a feedback sense, by another classical PID controller

with anti-windup. The error on which this controller acts is:

werror = we - wt

where wt is the transmission RPM with which the engine must be synchronized to avoid jerk when the

clutch is re-engaged.

This controller acts on the throttle input only.

Wheel-lift compensation

Controller-induced wheel-spin-up or wheel-lock is prevented by detecting when the loads on the driven wheels go to zero (that is, the driven wheels are not in contact with the road). In this case, the throttle and


brake are released (set to zero) and the clutch is depressed. The clutch action ensures that when the vehicle lands, the wheels spin up to the correct velocity as quickly as possible.

Adams/CarControlling Analysis Output Files

354

Controlling Analysis Output FilesYour template-based product lets you control the type and content of files an analysis outputs. You can specify whether an analysis outputs a graphics file or results file. Graphics files contain time-dependent data describing the position and orientation of each part in the model. Results files contain a basic set of state variable information that Adams/Solver calculates during a simulation.

Your template-based product automatically reads the files that an analysis outputs.

If any subsystems within the assembly being analyzed contain flexible bodies, your template-based product automatically outputs a results file, regardless of the specifications you made.

To specify analysis output files:

1. From the Settings menu, point to Solver, and then select Output Files.

The Output Files dialog box appears.

2. Select the types of files you want to output.

3. Select OK.

355Running AnalysesControlling Analyses Using CONSUBs

Controlling Analyses Using CONSUBsAdams/Car makes extensive use of the CONTROL command and associated CONSUB user subroutines to perform specific analysis tasks in Adams/Solver. These include moving suspension models from the design position to full jounce while suppressing output and running quasi-static steady-state analyses like constant radius cornering. If you customize Adams/Car or if you want to better understand the contents of the Adams Command Files (.acf) that Adams/Car writes, then the table below describing the purpose of these CONSUBS along with the links to further documentation of the input parameters, will be of use to you.

Controlling Full-Vehicle AnalysesIf you are an experienced Adams/Car user and you want to perform some non-standard full-vehicle analyses, such as studying the linear behavior of your vehicle between two mini-maneuvers, you can use an Adams/Solver control subroutine (Eventxxx) to do so.

When you run a full-vehicle analysis, Adams/Car writes a number of files to the current working directory (as defined by File -> Select Directory). These files contain important information about the

ID Description

900 Runs one or more static solutions to, for example, to adjust tie rod length to set desired toe angle. Adams/Car adds a call to this consub when the assembly contains adjustable forces. See Align or Adjust Suspension.

910 Set part velocity and wheel rotational velocity. See Part Velocity Setting.

917 Set part velocity and wheel rotational velocity. See Set Part Velocity.

950 For a suspension assembly, run a quasi-static simulation from time zero (0) to time one (1) to position the suspension at the first point in the loadcase file. Output from Adams/Solver to the request, graphics, and results files is suppressed so that plots generated for suspension characteristics verses wheel travel do not have duplicate points

See Move Suspension to Initial Position.

1010 Fixed Body Equilibrium. This is also know as a "settle" analysis.

1020 Static Steady-State Straight Line Equilibrium and Static Steady State Acceleration/Braking. Note in Adams/Car the auxiliary column joint is not used.

1021 Quasi-Static Steady-State Straight Line Acceleration/Braking Equilibrium. This sweeps the longitudinal acceleration between 0 and an ending value.

1030 Static Steady-State Cornering Equilibrium

1031 Quasi-Static Steady-State Cornering Equilibrium

1032 Quasi-Static Steady-State Swept Steer Equilibrium

1060 Quasi-Static Milliken Moment Method Analysis

Adams/CarControlling Analyses Using CONSUBs

356

details of the maneuver. In particular, two files are important in defining the scope of the maneuver. These are the Adams/Solver control file (.acf) and the event file (.xml).

The following shows the typical contents of an .acf:

file/model=test_steppreferences/solver=F77output/nosepcontrol/ routine=abgVDM::EventInit, function=user(3,1,10,0,2,5,7,9,4,8, 17)control/ routine=abgVDM::EventRunAll, function=user(0)!stop

In the .acf, note the following line:

control/ routine=abgVDM::EventInit, function=user(3,1,10,0,2,5,7,9,4,8, 17)

This line calls an Adams/Car-specific control subroutine (a consub). The consub sets up and initializes the full-vehicle analysis. It does the following:

• Reads the event file (or converts the TeimOrbit .dcf file into XML)

• Performs a number of static analyses based on the content of the DcfStatic class in the event file

• Performs a dynamic analysis by running each of the mini-maneuvers listed in the DcfMini classes in the event file

You can view and modify the event file (.xml) using the Event Builder. The Event Builder allows you to modify existing parameters for the entire maneuver, such as step size and hmax, to modify specific mini-maneuver information, and add mini-maneuvers.

The following line calls the control subroutine EventInit:

control/ routine=abgVDM::EventInit, function=user(3,1,10,0,2,5,7,9,4,8, 17)

The call to this subroutine passes 11 parameters, as described next. Note that each number in the array (3,1,10,0,2,5,5,9,4,8, 17) is listed after the description of that parameter.

par(1) 3: ID of STRING statement containing .XML event filename = 3 par(2) ID of ORIGO marker = 1par(3) ID of ARRAY statement containing initial condition SDI parameters = 10par(4) ID of ARRAY statement containing ids of parts for which initial velocity are not set = 0par(5) ID of ARRAY holding Vehicle Parameters. = 2par(6) ID of main Driving Machine ARRAY. = 5par(7) ID ISO EAS Marker = 7par(8) ID of Driver_Parameters_ARRAY_Steering_Human = 9par(9) ID of STRING statement containing Driver Road Filename = 4par(10) ID of ARRAY containing Human Driver Parameters = 8par(11) ID of ARRAY containing the ids of extensible end condition sensor elements = 17

357Running AnalysesControlling Analyses Using CONSUBs

If you look at the corresponding Adams/Solver dataset (.adm), you will see that STRING/3 contains the name of the event file:

! adams_view_name='testrig_dcf_filename'STRING/3, STRING =example_crc.xml

All standard Adams/Car events generate an event file in XML format, similar to the one referenced in the example above, but .dcf files in TeimOrbit format are still supported, both in the Event Builder and at the solver level. This means that you can replace the above string and reference a .dcf file in TeimOrbit format. The file will be automatically converted to XML format.

By modifying the .acf file, you can now execute all mini-maneuvers defined in the event file, or just run the initialization and then execute one mini-maneuver at a time. Full-vehicle analysis .acf files by default call the Driving Machine initialization routine, then call the RunAll method. You can, however, modify the .acf file and use the following commands for more control over your analysis:

• control/ routine=abgVDM::EventRunAll, function=user(0) - Runs all the active mini-maneuvers in the list of events

• control/ routine=abgVDM::EventRunNext, function=user(0) - Runs the following mini-maneuver in the list of the events

• control/ routine=abgVDM::EventRunFor, function=user(time) - Runs the current mini-maneuver for duration of time [s]

• control/ routine=abgVDM::EventRunUntil, function=user(time) - Runs the current mini-maneuver until the desired absolute time [s]

Using this flexibility within the event control subroutine enables you to use the power of the acf language to make changes and re-submit your solution to Adams/Solver. The language parameters for the .acf file are documented in the Adams/Solver online help.

Adams/CarControlling Analyses Using CONSUBs

358

Configuring Your Product

Adams/CarAbout the Management Tasks

366

About the Management TasksWhen you start your template-based product, it automatically creates the necessary files for you to begin working immediately. As you become more familiar with your template-based product, you may find that you want to set up custom private versions of it or change the way it is configured. In addition, you may want to set up custom site versions that several users can share.

The template-based products let you do these different management tasks depending on the type of user access you have been assigned. You should give one user, who has expert-user access, the responsibility of managing the site version, if you have one, of your template-based product so only one user, the site manager, makes changes.

The following table lists the different management tasks that you can perform depending on your user access. You can perform many of these tasks using the menus in your template-based product. Other tasks require you to set variables in different configuration files.

Management Tasks by User Type

To access management tools:

Your access to management tools depends on your user access:

• Standard users - You can access your template-based product's tools that let you manage your private database. The tools are under the Tools menu.

• Expert user - You can access the management tools from the Tools menu.

To get expert-user access, modify your private .acar.cfg configuration file and change your user mode to EXPERT. Learn about setting your product's environment.

This type of user: Can:

Standard user • Create and set up private databases in which to store files, such as subsystems and property files, with which you are working.

• Make copies of files in your private database or copy the entire database to share with other users.

• Configure the operation of your template-based product for your private use.

Expert user • Perform the same tasks as a standard user.

• Publish a template so all users can use it.

Site manager • Set up site databases in which general project information is stored.

• Define the access that users can have to functionality.

• Set up a custom version of your template-based product and configure its operation.

• Assigns access to common databases to allow read and write permissions for standard and expert users.

367Configuring Your ProductAbout Database Management

About Database Management The template-based products define assemblies using several different files. The files define the topology, dynamic element characteristics, analysis information, and more. Your template-based product stores these files in hierarchical databases.

The template-based products provide two types of default databases:

• Private database for each user - A private database is for your personal use. You can store and retrieve data from your private database. In addition, you can share your private database with others. If a private database does not exist, your template-based product creates the private database at the beginning of a session.

• Shared database for all users - A shared database provides all users with access to standard, accurate data. To prevent loss of data or the storing of inaccurate data in a shared database, standard users can only retrieve data from a shared database. Typically, only the site manager has the permissions necessary to create files in a shared database. An example of a shared database is distributed with your template-based product, and it is usually placed in the installation directory.

Learn more about databases:

• Database Structure

• About the Database Search List

Database StructureEach database consists of one directory (*.cdb) and several subdirectories (*.tbl), called tables. Each subdirectory contains files for specific types of components, such as springs and dampers, or files for performing tests, such as loadcases and wheel envelopes. The number of tables varies, but you can define the number in the shared and private configuration files.

By default, your template-based product divides a database into the following table elements:

• Models and topological information (templates, assemblies, subsystems, and flexible bodies)

• Analysis information (such as analysis scripts, loadcases, driver loadcases, and suspension curves)

• Postprocessing (plot configuration files)

• In Adams/Car, driver files (such as driver inputs and roads)

• In Adams/Car, tires and roads

• Property files (such as springs, dampers, and remaining tables)

Each type of file that a table stores has a unique three-letter extension that identifies its contents. For example, all files stored in the assembly table contain a .asy extension.

Adams/CarAbout Database Management

368

An example of the default structure of a database for Adams/Car is shown in the Information window. The information window shows all the tables in the database, their names, the type of files they store, and the file extension of the files that they store.

You can also add your own tables since the database is an open-architecture file repository. For example, you might want to create a table that stores data files for an analysis that is specific to your company. Learn about managing tables.

About the Database Search ListDuring startup, your template-based product stores any databases that are defined in your private, site, and shared configuration files in its search list. The databases in the search list are the only databases that appear in dialog boxes when you select to display databases and files, such as subsystem or property. For example, when you want to change the database to which you can write files, your template-based product only displays those databases in its search list in the dialog box.

Your template-based product searches the databases in its search list using a search order that you can modify.

You can change the databases in the search list and their search order either by using the menus or by editing the configuration files directly. All configuration files can define the databases, including the private, site, and shared configuration files.

369Configuring Your ProductAbout Database Management

For your template-based product to be able to store a database in its search list, the file system to which the database points must be accessible on the current file system of the computer.

Learn about setting up the search list and the order in which databases are searched.

Adams/CarManaging Databases

370

Managing DatabasesSelect a topic to learn about the operations you can perform on databases:

• Creating Databases During a Session

• Setting the Writable Database

• Managing Tables in a Database

• Creating Tar Files of Databases

Creating Databases During a SessionYou can create a new database anytime during a session. When you create a database, your template-based product adds it to its search list and places the database at the lowest level in its database search order. Your template-based product also creates database tables within the new database according to the table information stored in your private, site, and shared configuration files. Learn about search order.

You should create a database for every project on which you are working. By creating separate databases for each project, you can ensure that the property files belonging to different subsystems are kept separate.

When you create a database, you define two elements for it:

• Name - You use the name, or database alias, to select the database from the search list in dialog boxes.

• Path - The location of the database in the file system.

To create a database:

1. From the Tools menu, point to Database Management, and then select Create Database.

2. Press F1 and then follow the instructions in the dialog box help for Create New Database.

3. Select OK.

Setting the Writable DatabaseYou can set up one of your active databases as the repository for templates, subsystems, and property files. This database is called your default writable database. The default writable database is defined in

Note: Unless you save database changes to your private configuration file, Adams/Solver will not be able to access the databases you added or created in a session

Note: You can also create databases directly using the configuration files. Learn about managing databases through configuration files.

371Configuring Your ProductManaging Databases

your private configuration file, but you can change it at anytime during a session. You can select any database in the search list as your default writable database, as long as you have permission to write to the file system to which the database points.

To create a database:

1. From the Tools menu, point to Database Management, and then select Set Default Writable.

2. Press F1 and then follow the instructions in the dialog box help for Set Default Writable Database.

3. Select OK.

Managing Tables in a DatabaseYou can add your own tables to a database. You use the configuration files to define the tables that you want to include in a database. Learn more about configuration files and table definitions in them.

Creating Tar Files of DatabasesOn UNIX, you can create a tar file of any database that is listed in the search list. When you create a tar file of a database, your template-based product groups together all of the database's subdirectories and files into one tar file. It then writes the tar file to the default writable database using the name database_name.tar, where database_name is the name of the database you saved.

Saving a database as a tar file is an efficient way to save a snapshot of the current state of a database or to transfer the database to an external file system. You can easily transfer the databases through e-mail or through a file transfer protocol (ftp) process.

As you create a tar file, you can select to encode and compress the database using standard UNIX compression and encoding techniques.

To create a tar file of a database in UNIX:

1. From the Tools menu, point to Database Management, and then select Bundle Database.

2. Press F1 and then follow the instructions in the dialog box help for Bundle Database.

3. Select OK.

Adams/CarSetting Up the Search List and Order

372

Setting Up the Search List and OrderAs explained in About the Database Search List, your template-based product stores in its search list, all the databases currently defined in your configuration files. When you request a file from the databases, your template-based product uses a defined search order to search the databases for the requested file.

See the following topics to learn more about the search order, how it impacts you, and how you set it up:

• About Search Order

• Adding Databases to the Search List

• Removing Databases from the Search List

• Changing the Search Order

About Search OrderDuring a session, you can have many databases listed in the search list. Your template-based product assigns to each database in the search list a numerical value representing its place in the search order. For example, if there are three databases in your search list, your template-based product numbers them 1, 2, and 3, with 1 representing the first database it searches.

When you request a file, such as a property file, your template-based product searches the databases in the specified search order. It first tries to open the file as specified. If the filename has a database alias, your template-based product expands it to a full file system path.

If your template-based product cannot find the file in the specified database, it begins searching the other databases in its search list in the search order. Your template-based product begins with the first database in the search order. It continues through all the databases in the search order until it finds a matching filename.

Your private configuration file sets the search order of these databases, but you can change it at anytime during a session.

Note that in many cases changing the database search order can cause your template-based product to find a different file. For example, if two databases contain a file with the same name but with different data, changing the search order may change which file your template-based product uses. You may find this helpful in many cases, but it can produce unintended results when you change the search order

Note: By default, your template-based product doesn't search all defined databases when it cannot locate a file. You can, however, re-enable the searching by setting the MDI_CDB_SEARCH environment variable to yes. In the Command Navigator, you can issue the following command:

variable set variable_name=do_search &integer_value=(putenv("MDI_CDB_SEARCH","yes"))

For more information, see the Adams/Car release notes.

373Configuring Your ProductSetting Up the Search List and Order

without realizing that you can access different files. The database search order is also important if you specify the database path incorrectly.

To avoid using the search order to find a file, which can result in longer searches and unintended results, you can specify the database name (its alias) directly in the associated property file to ensure that your template-based product searches the correct database.

You can look at the search order of the databases in the search list using the Database Info command, as shown in Viewing Database and Table Information. Your template-based product displays the current list of databases, showing the search order level of each database in the first column. Learn about displaying database information.

Adding Databases to the Search ListAs you are working with your template-based product, you can add databases to the current search list. Your template-based product adds the databases to the end of the search order. Learn about changing the search order.

To add a database to the search list:

1. From the Tools menu, point to Database Management, and then select Add to Search.

2. Press F1 and then follow the instructions in the dialog box help for Add Database to Search.

3. Select OK.

Removing Databases from the Search ListYou can remove a database from the search list so that your template-based product does not search for files in it. Removing a database from the search list does not remove the database from the file system.

If you want to remove the current default writable database from the search list, you must first specify another database as the default writable database.

To remove a database from the search list:

1. From the Tools menu, point to Database Management, and then select Remove from Search.

2. Press F1 and then follow the instructions in the dialog box help for Remove Database From Search.

3. Select OK.

Changing the Search OrderYou can change the order in which your template-based product searches databases for files. Learn about search order.

Adams/CarSetting Up the Search List and Order

374

To change the search order:

1. From the Tools menu, point to Database Management, and then select Change Search Order.

2. Press F1 and then follow the instructions in the dialog box help for Change Database Search Order.

3. Select OK.

375Configuring Your ProductSaving and Publishing Database Information

Saving and Publishing Database Information

Viewing Database and Table InformationYou can view the current set of databases in the search list. The information includes the database names, file system paths, and levels in the current search order. You can also view the table structure of the current writable database.

To view database information:

1. From the Tools menu, point to Database Management, and then select Database Info.

2. View the database information, and then select Close.

To view the tables in the writable database:

• From the Tools menu, point to Database Management, and then select Table Info.

• View the table information, and then select Close.

Saving Database Management ChangesAt any point during a session, you can save the list of databases that is currently available during the session and the search order to your private configuration file. Learn about private configuration files.

To save database management changes:

• From the Settings menu, select Save <product name> Configuration.

Publishing SubsystemsWhen you publish a subsystem, you copy the subsystem file and all its associated property files to the target database, which is the database where your template-based product saves all files. You can also select to publish the subsystem's template file. As you publish the subsystem, you can choose to write over existing files or create backups of the files.

You can also select to update the in-session subsystem data to point to the target database or to have the subsystem retain the existing references.

The subsystem you are publishing must be currently opened in the standard interface, and the target database must be writable. Learn about setting the writable database.

You can also publish an entire assembly. Learn about publishing an assembly.

To publish a subsystem:

1. From the Tools menu, point to Database Management, and then select Publish Subsystem.

2. Press F1 and then follow the instructions in the dialog box help for Publish an Open Subsystem.

3. Select OK.

Adams/CarSaving and Publishing Database Information

376

Publishing AssembliesWhen you publish an assembly, you copy each subsystem file included in the assembly definition, including the associated property files for each subsystem, to the target database, which is the database where your template-based product saves all files. You can also select to publish each subsystem's template file. As you publish the assembly, you can select to write over existing files or create backups of the files.

You can also select to update the in-session assembly data to point to the target database or to have the assembly retain the existing references.

The assembly you are publishing must be currently opened in the standard interface, and the target database must be writable. Learn about setting the writable database.

You can choose to publish only a subsystem, not an entire assembly. Learn about publishing a subsystem.

To publish an assembly:

1. From the Tools menu, point to Database Management, and then select Publish Assembly.

2. Press F1 and then follow the instructions in the dialog box help for Publish an Open Assembly.

3. Select OK.

377Configuring Your ProductAbout Configuration Files

About Configuration FilesYour template-based product's configuration file contains information that your template-based product reads during startup to correctly initialize the session. Your template-based product looks for the following configuration files when it starts up: shared, site (if it exists), and private configuration files, in that order.

The private configuration file contains personal settings that are then merged with the general settings defined in the shared or site configuration file. Together, the settings define your work environment. The shared and private configuration files are required, while the site configuration file is optional. You use the site configuration file only if you want to set up a custom version that all users can access.

To personalize the settings in the configuration files, you edit the configuration file using a text editor. You can, however, use the menus to set up the databases without having to directly edit the configuration files. Learn about managing databases.

Each of the configuration files is explained in the next topics:

• About Private Configuration Files

• About Site Configuration File

• About Shared Configuration File

• About Plugin Configuration Files

About Private Configuration FilesAs an expert or standard user, you have your own private configuration file with a default name of .acar.cfg. Your template-based product accesses this file at the beginning of every session. The private configuration file is found at $HOME/.acar.cfg, where $HOME is the location of your home directory.

If you have more than one private configuration file, you can choose the file you want to use for a given session. Depending on the platform you are using, you do the following:

• On UNIX - You use the Registry Editor on the Adams Toolbar to choose the file you want to use. The registry setting name for your private configuration file is privateCfg. Learn about Adams Registry Editor.

• On Windows - You can specify the private configuration file using an environment variable. You can set this environment variable using the System option from the Control Panel, just as you would for any other variable. Depending on your template-based product, you can specify the following environment variables:

• For Adams/Car, enter MDI_ACAR_PRIVATE_CFG

• For Adams/Driveline, enter MDI_ADRV_PRIVATE_CFG

Note: The private configuration file is not located in the installation directory. Never change the acar.cfg file located in the installation.

Adams/CarAbout Configuration Files

378

You should set up your private configuration file so it contains information specific to the work you are performing. For example, you can set up your own tables in databases in which to store project data. You can also override many of the default settings provided in the shared and site configuration files.

When you set up your private configuration file using the Adams Registry editor, the location specified for privateCfg is saved in a file $HOME/.msca/msca_MDx.reg. Where x represents version number and $HOME is the home directory; for example, C:/.msca/msca_MD2010.reg for MD Adams 2010. This enables you to specify a different location when you use a different version of Adams. For example; if a new location is specified for the privateCfg when using Adams 2008 r1; this setting is stored in the file $HOME/.msca/msca_2008r1.reg and each subsequent usage of Adams 2008r1 will use the privateCfg file specified in this file.

About the Site Configuration FileIf you create a site configuration file, you call it <your_product_name>.cfg, and place it in the template-based product site repository. You can have only one site configuration file for a site installation of your template-based product. The site configuration file provides settings common to users at a particular site. See Organizing Custom Code to learn about the location of the site repository.

For example, your company may have engineers working across a network, each wanting to access some common information, such as files and variables. You could set up the site configuration file so that when they run the site version, each engineer's session is configured to access the common information.

We recommend that only the site manager changes the site configuration file. You should make any personal modifications using private configuration files.

About the Shared Configuration FileThe shared configuration file is called <your_product_name>.cfg, and is generally found in the installation directory. See your system administrator for location details.

Only one shared configuration file exists for an installation of your template-based product. The shared configuration file contains predefined information common to all users.

We recommend that no one changes the shared configuration file. You should make any personal modifications using private configuration files, and any common changes for multiple users in site configuration files.

About Plugin Configuration FilesMany plugins that work with the Template Builder have their own shared and site configuration files.

Your template-based product follows the same logic for processing the plugin configuration files as it does for any other configuration file.

379Configuring Your ProductAbout Configuration Files

Format of Configuration FilesA configuration file is divided into the blocks listed below. An example of the blocks in a configuration file are shown in figure Configuration File Blocks. In the example, ! indicates comments.

• Environment Variables - The first block in a configuration file sets up the environment of your template-based product. For example, it identifies the type of user associated with the configuration file. It also sets the mode in which your template-based product starts, Standard Interface or Template Builder, and any other environment settings.

• Databases - The second block defines the databases in which users store files, the order in which your template-based product searches databases, and the database to which files are written by default.

• Table Directories - The third block defines the list of personal table directories. For example, you could create a table in which to store examples.

• Property Files - The fourth block contains a listing of default property files. When a dialog box requires a property file, it automatically knows to load the desired files if you enter property files in the property file block. You usually define property files in the shared configuration file. If you enter values in your private configuration file, your template-based product overrides the shared files with your personal property files.

• Test Rigs - The fifth block defines the default test rig for a given assembly class. When a dialog box requires a test rig, it automatically knows to load the desired test rigs. You usually define test rigs in the shared configuration file.

Configuration File Blocks !-------------------------------------------------------------------! !*************** Adams/X Configuration File *************** ! !-------------------------------------------------------------------! !-------------------------------------------------------------------! ! - List of personal environment variables !-------------------------------------------------------------------! ENVIRONMENT MDI_ACAR_USERMODE expert !-------------------------------------------------------------------! ! - List of personal database directories ! Database name Path of Database !-------------------------------------------------------------------! DATABASE private /usr/private.cdb DATABASE staff /staff/private.cdbDEFAULT_WRITE_DB private! !-------------------------------------------------------------------! ! - List of personal tables directories ! Type class Name of table Extension !-------------------------------------------------------------------! ! Example table entry: !TABLE list2+ example.tbl exa ! !-------------------------------------------------------------------! ! - List of personal default property files ! Type class Default property file !-------------------------------------------------------------------! ! Example property file entry:

Adams/CarAbout Configuration Files

380

!PROPFILE assembly <private>/assembly.tbl/myfile.dpr ! ! Example test rig entry: !TESTRIG four_post .__MY_FOURPOST

381Configuring Your ProductSetting Up the Environment Through Configuration Files

Setting Up the Environment Through Configuration FilesTo work efficiently with your template-based product, you must set a standard set of environment variables in a configuration file. The environment variable has the following format:

ENVIRONMENT VARIABLE_NAME VARIABLE_VALUE

We've set up default environment variables in the shared configuration file, but we recommend that you redefine them in the private or site configuration file to customize the work environment of your template-based product. You can also define your own environment variables for use with user-written subroutines or macros. See a list of Environment Variables.

Learn about the standard environment entries that you can set and how to create your own environment variables:

• Setting User Access

• Accessing Adams/View

• Setting Defaults and Display of the Welcome Dialog Box

• Replacing the Image on the Welcome and Exit Dialog Boxes

• Setting Up Side Preferences

• Setting the Orientation of the Global Reference Frame

• Managing Result File Output

• Redefining Environment Variables

• Defining Your Own Environment Variables

• Editing Files Using a Text Editor

Setting User AccessYou use the MDI_ACAR_USERMODE keyword in your private configuration file to set your user access, which determine you access to the Template Builder and other development tools (learn About User Access). Your private configuration file is found at $HOME/.acar.cfg, where $HOME is the location of your home directory.

You can set USERMODE to:

• STANDARD - User can only access the Standard Interface.

Note: The private configuration file is not located in the installation directory. Never change the acar.cfg file located in the installation.

Adams/CarSetting Up the Environment Through Configuration Files

382

• EXPERT - User can access the Template Builder and create and modify templates. User can access the Template Builder and other development tools that are located under the Tools menu. Expert users can use the MDI_ACAR_PLUS_AVIEW keyword in the private configuration file to access Adams/View. Learn about accessing Adams/View.

To change the value of this keyword, you must edit the private configuration file (.acar.cfg) using a text editor and modify the corresponding string. The following gives you expert access:

! Desired user mode (standard/expert)ENVIRONMENT MDI_ACAR_USERMODE EXPERT

When you start a new session, your template-based product reflects the changes to the private configuration file.

Accessing Adams/View If you are an expert user, you can use the MDI_ACAR_PLUS_AVIEW environment variable in the private configuration file to obtain access to Adams/View.

MDI_ACAR_PLUS_AVIEW has the following format:

ENVIRONMENT MDI_ACAR_PLUS_AVIEW (yes, no)

To access Adams/View:

1. Set MDI_ACAR_PLUS_AVIEW to yes.

2. From the Tools menu, select Adams/View Interface.

To return to your template-based product:

• From the Tools menu, point to Select Mode, and then select the interface mode to which you want to return: Standard Interface or Template Builder.

Setting Full Vehicle Solver Preference/Solver PreferenceYou can set your solver preferences, either from the settings menu or in your private configuration file.

See Solver Selection dialog box help.

Setting HHT Integrator Preferences If using Adams/Solver (C++), you can also set a preference for using the HHT integrator as the the default integrator, as explained next.

To set HHT integrator preference:

1. In a text editor, such as Jot or Notepad, open .acar.cfg in your home directory.

2. Add the following line to set HHT as the default integrator:


ENVIRONMENT MDI_AENG_HHT_ERROR 1e-5This sets the HHT integrator as the default integrator with a default error tolerance of 1e-5 when using Adams/Solver (C++).

3. Start a new session.

Setting Defaults and Display of the Welcome Dialog Box

Setting Defaults

You can use the MDI_ACAR_INITMODE environment variable to set the default selection in the Welcome dialog box when the user has expert-user access. MDI_ACAR_INITMODE has the following format:

ENVIRONMENTMDI_ACAR_INITMODE (template_builder, standard_interface)

In Adams/Driveline for example, if you set MDI_ACAR_INITMODE to standard_interface, the Welcome dialog box sets the selection of Standard Interface as the default, as shown next.

Setting the Display

You can use the MDI_ACAR_MODEPROMPT environment variable to set your template-based product so that it does not display the Welcome dialog box at start up. MDI_ACAR_MODEPROMPT has the following format:

ENVIRONMENTMDI_ACAR_MODEPROMPT (yes, no)

Setting it to yes displays the Welcome dialog box; setting it to no turns off the display of the Welcome dialog box.


384

Replacing the Image on the Welcome and Exit Dialog BoxesYou can replace the image on the Welcome and Exit dialog boxes with another image.

To replace the image:

1. Create a color X pixmap image (.xpm) with a size of approximately 197 x 192 pixels.

2. Copy the new pixmap file to a designated directory.

3. Add the following entry in your .acar configuration file:

ENVIRONMENT MDI_ACAR_LOGO_BMP <your_directory/filename>

Setting Up Side PreferencesYou can use the MDI_ACAR_SIDE_PREF environment variable to define the preferred side for creation. When you set the side preferences:

• The creation dialog box in the Template Builder sets the default type based on the side preference you set.

• The guesses in the pop-up menus in dialog boxes only contain left and single or right and single entities based on the side preference. Your template-based product does this to limit the number of guesses.

The MDI_ACAR_SIDE_PREF environment variable has the following format:

ENVIRONMENT MDI_ACAR_SIDE_PREF (right, left)

Setting the Orientation of the Global Reference FrameYou can set the orientation of the global reference frame using direction cosines. You use either of the following environment variables to define the orientation:

ENVIRONMENT MDI_ACAR_VEHICLE_REAR 1,0,0ENVIRONMENT MDI_ACAR_VEHICLE_LEFT 0,-1,0

Managing Result File OutputResult files include all the simulation output from an analysis. The following environment variable sets the default attribute of whether the result file is output during the analysis. If the assembled model contains flexible bodies, your template-based product automatically outputs a result file regardless of the environment variable setting.

If the assembled model does not contain flexible bodies, use the following command (example is for Adams/Car) to indicate that you want your template-based product to output a result file:

ENVIRONMENTMDI_ACAR_WRITE_RES (yes, no)


If a result file exists, your template-based product will automatically read it in with the analysis, if you run an interactive simulation.

If you run the simulation externally (background, files_only), you can read in the result file using either of these two methods:

• Review -> Analysis Management -> Read

• File -> Import -> Adams Results File (*.res)

Redefining Environment VariablesWe've set up default environment variables in the shared configuration file, but we recommend that you redefine them in the private or site configuration file to customize the work environment of your template-based product.

To redefine environment variables, use the format below. Your template-based product initializes the variables at startup.ENVIRONMENT VARIABLE_NAME VARIABLE_VALUE

The following gives you expert access to your template-based product:

ENVIRONMENT MDI_ACAR_USERMODE expert

List of Environment Variables.

Defining Your Own Environment VariablesYou can define your own environment variables in the private and site configuration files for use with user-written subroutines or macros. For example, you can define a variable named debug_mode in your private or site configuration file. Then, in your own macros, you can query for the value of debug_mode, and execute some instructions depending on its value. The example below shows a portion of the macro that would query for the value of debug_mode:

IF condition =(getenv("debug_mode")=="yes")default command echo=on

END...

To define your own environment variables, use the format below. Your template-based product initializes the variables at startup

ENVIRONMENT VARIABLE_NAME VARIABLE_VALUE

For the previous example, you would use the following:

ENVIRONMENT debug_mode yes


386

Editing Files Using a Text EditorYou can use an environment variable, MDI_ACAR_USE_EDITOR, to edit files from within your template-based product. Adding this environment setting to your .acar.cfg file causes the View Property

File tool to launch a text editor instead of the Information window.

If this environment variable is not set, external files will be shown in the info window. If it is set to any value, the default browser is used to visualize .xml files and notepad.exe is used to open any other file. The default editor for non-xml files can be changed by specifying the path via the Adams Settings utility (Adams registry editor -> AView -> Preferences -> textEditor). In the variable, simply specify the location of your preferred text editor executable.

For example, an Adams/Car user who wants to launch Wordpad would set up the environment variable as follows:

ENVIRONMENT MDI_ACAR_USE_EDITOR yes

and specifies the following path for textEditor field using Adams Settings utility as described above.

C:\Program Files\WindowsNT\Accessories\wordpad.exe

387Configuring Your ProductManaging Databases Through Configuration Files

Managing Databases Through Configuration Files You can use two environment variables to manage your template-based product's databases in the configuration file:

• DATABASE - Sets up databases.

• DEFAULT_WRITE_DB - Sets the default writable database.

You can place DATABASE entries in the private, site, or shared configuration files. The DEFAULT_WRITE_DB, however, is reserved for the private and site configuration files.

Note that you can also set up databases through menus, as explained in Managing Databases. You may find it more convenient to use the menus.

Learn more about managing databases through configuration files:

• Setting Up Databases

• Specifying Default Writable Database

Setting Up DatabasesYou can define databases in your template-based product using the keyword DATABASE. A DATABASE keyword entry has the following format:

DATABASE DB_NAME DB_PATH

In the format, DB_NAME is the name assigned to the database and DB_PATH is the location of the database in your file system. You can add any database to the DATABASE definition in any configuration file. If the database does not exist, your template-based product creates it in the specified location and adds it to the database list.

Specifying Default Writable DatabaseYou can specify the database that you want to use as the database to which all files are written. You use the environment variable DEFAULT_WRITE_DB to define the default writable database. The DEFAULT_WRITE_DB environment variable has the following format:

DEFAULT_WRITE_DB DB_NAME

The environment variable defines the initial database that you want as the default location for writing files. Usually, you define the default writable database in your private configuration file, although you can set the writable database in any configuration file. You can change it during the session as explained in Setting the Writable Database. Note that you will need permission to write to the file system location to which the DEFAULT_WRITE_DB points.

Adams/CarManaging Tables Through Configuration Files

388

Managing Tables Through Configuration FilesAs explained in Database Structure, a template-based product's database is comprised of a number of directories or tables in which you store files. In addition to the standard set of table directories, you can create your own tables.

Generally, you only add table directories to the databases defined in your private configuration file. As the site manager, you may decide to add tables for general use in the site configuration file.

Learn more about creating tables and the standard table entries:

• Creating Tables

• Standard TABLE Directory Entries

Creating TablesAt start up, your template-based product determines when to create new table directories as follows:

1. Your template-based product verifies that all database directories defined in the private configuration file contain table directories for the corresponding table directories also defined in the private configuration file.

2. If a table directory does not exist inside the database, your template-based product creates one.

3. If a site configuration file exists, your template-based product ensures that for any table directory specified in the site configuration file, a corresponding table directory exists for all database directories defined in both the site and private configuration files.

4. Your template-based product ensures that for all table directories specified in the shared configuration file, a corresponding table directory exists for all database directories defined in the private, site (if it exists), and shared configuration files.

The TABLE keyword entry for creating tables has the format:

TABLE TABLE_CLASSTABLE_NAME TABLE_EXTENSION

where:

• TABLE_CLASS - A string identifying the table.

• TABLE_NAME - The name that you want used to access the table.

• TABLE_EXTENSION - The three-character extension of files stored in the table. Your template-based product only recognizes files in the table that have the extension that you specify.

For example, the following creates a table that stores aerodynamic forces:TABLE aeroforces /staff/my_name/my_db.cdb/aeroforces.tbl aer

Adding the table definition shown above in the configuration file causes your template-based product to recognize and correctly access files stored in that particular database table.

389Configuring Your ProductManaging Tables Through Configuration Files

Standard TABLE Directory EntriesThe TABLE directory entries in the shared configuration file are briefly explained in the following table:

The entry: Defines tables for:

TABLE assembly assemblies.tbl asy

Assembly files that list the subsystems that make up Adams/Car assemblies.

TABLE template templates.tbl tpl Template files that define the topology and major role (for example, suspension or steering) of Adams/Car models.

TABLE subsystem subsystems.tbl sub Subsystem files that contain information unique to the specific instance of the template the subsystem file references.

TABLE aero_force aero_forces.tbl aer Aero_force files that contain wind-force mappings.

TABLE bushing bushings.tbl bus Bushing files that define a six degree-of-freedom force relationships between user-specified locations on two parts.

TABLE linear bushing bushings.tbl lbf Bushing files that define a six degree-of-freedom force relationship between user-specified locations on two parts, using constant coefficients for each of the six degrees of freedom.

TABLE bumpstop bumpstop.tbl bum Bumpstop files that define a force-displacement relationship between user-specified locations on two parts.

TABLE damper dampers.tbl dam Damper files that define a force-velocity relationship between user-specified locations on two parts.

TABLE linear damper dampers.tbl ldf Damper files that define the linear damping force relationship between user-specified locations on two parts, using a constant damping coefficient.

TABLE flex_body flexbodys.tbl mnf Files that define flexible body representations usually through modal neutral files.

TABLE powertrain powertrains.tbl pwr Powertrain files that define the engine speed-torque relationship at different throttle positions.

TABLE differential differentials.tbl dif Differential files that define the slip speed-torque characteristics of a differential.

TABLE reboundstop reboundstops.tbl reb Rebound stop files that define a force-displacement relationship between user-specified locations on two parts.

TABLE shell_graphic shell_graphics.tbl shl

Shell graphic files.


390

They are the standard set of tables that are distributed with your template-based product's database. You cannot reconfigure TABLE entries. Changing these values disables your template-based product's ability to assign properties to a class of entities.

TABLE spring springs.tbl spr

Spring files that define a force-displacement relationship between user-specified locations on two parts.

TABLE linear spring springs.tbl lsf Spring files that define the linear elastic force relationship between user-specified locations on two parts, using a constant stiffness coefficient.

TABLE steering_assist steering_assists.tbl ste

Steering_assist files that contain torsion bar data relating torsion bar deflection to both torque and pressure.

TABLE tire tires.tbl tir

Tire files that define data needed to characterize tire behavior (a tire model).

TABLE road roads.tbl rdf

Road files that define roads that the contact algorithms in the Adams/Tire module use.

TABLE driver_controls driver_controls.tbl dcf

Driver control files that contain maneuver descriptions for the Driving Machine. Also includes XML event files. For additional information, see Note in Using the Driving Machine.

TABLE driver_data driver_data.tbl dcd

Driver data files that contain data for the Driving Machine.

TABLE driver_loadcase driver_loadcases.tbl dri

Driver loadcase files that contain driving signals used in a data-driven, full-vehicle analysis. The driver loadcase specifies inputs to the vehicle.

TABLE loadcase loadcases.tbl lcf Loadcase files that contain data used in suspension analyses.

TABLE suspension_curve suspension_curves.tbl scf

Suspension curves used in the Conceptual Suspension Modeling module.

TABLE wheelenv wheel_envelopes.tbl wen

Wheel-envelope files that contain location vector information that represents the wheel-center location and orientation in space. They are used for wheel-envelope analyses.

TABLE plot_config plot_configs.tbl plt Plot configuration files that define a suite of plots to be automatically generated after completion of an analysis.

TABLE driver_road driver_roads.tbl drd Adams/Driver road definitions.

TABLE driver_knowledge driver_knowledge.tbl kno

Adams/Driver knowledge file. (Obsolete).

TABLE driver_input driver_inputs.tbl din Adams/Driver input files used in an Adams/Driver full-vehicle analysis. (Obsolete).

The entry: Defines tables for:

391Configuring Your ProductManaging Tables Through Configuration Files

Managing Property Files Through Configuration FilesA PROPFILE environment variable in the configuration file assigns a default property file used when creating the following entity types: bumpstop, bushing, damper, reboundstop, spring, and tire.

A PROPFILE environment variable in a configuration file has the following format:

PROPFILE PROPFILE_CLASS PROPFILE_NAME where:

• PROPFILE_CLASS is a string that identifies the property file.

• PROPFILE_NAME is the name of the property file.

For example:

PROPFILE bushing mdids://shared/bushings.tbl/mdi_0001.bus

You can define the property files in the private, site, or shared configuration files.

Managing Test Rigs Through Configuration FilesA TESTRIG environment variable in the configuration file assigns a default test rig to a particular class of assemblies.

A TESTRIG environment variable in a configuration file has the following format:

TESTRIG TESTRIG_CLASS TESTRIG_NAME where:

• ASSEMBLY_CLASS is a string that identifies the type of assemblies which correspond to the test rig.

• TESTRIG_NAME is the name of the test rig model.

For example:

TESTRIG four_post .__MY_FOURPOST

You can define the default test rigs in the private, site, or shared configuration files.


392

Customizing Your Product

Adams/CarOverview

392

OverviewIf you are an expert user or site manager, you can customize your template-based product to your company's needs and preferences. You can extend your template-based product by adding new functionality, modifying standard functionality, or tailoring its appearance to fit the needs of your work environment. Customizing your template-based product lets you create a familiar environment in which users can work. Learn about Setting User Access.

You can typically modify your template-based product in three main areas. These require different levels of understanding, ranging from the Adams macro language, Standard Developer Kit (Adams/SDK), through FORTRAN and C solver routines, as described next.

• Customizing the interface - Involves creating or modifying interface objects, such as macros, dialog boxes, menus, and windows. This uses Adams command language to modify the look and feel of the interface. It can be used to automate recurring tasks, using the scripting language, but has limitations in terms of speed and would not be used to generate computationally complex objects (1000 parts located and oriented to generate a chain). For these tasks, you would use an Adams/View library written in C.

• Creating a custom Adams/View library - Takes advantage of user-written subroutines and functions to automate highly repetitive and computationally complex tasks in an efficient manner, using C. Using functions delivered in the SDK, you can quickly generate and manipulate Adams elements.

• Creating a custom Adams/Solver library - Create user-written subroutines and functions to extend the functionality of your template-based product in terms of the solver. You save them in custom libraries for later use.

Once you have finalized your customization of your template-based product, you can store your customized dialog boxes, macros (binary files), Adams/View and Adams/Solver libraries in a site

Note: You cannot customize all dialog boxes and tools. For example, you cannot customize the Plugin Manager or the Information window. The Dialog-Box Builder's Dialog Box -> Open menu provides access to those dialog boxes, containers, and toolbars that you can customize.

Note: You save interface objects and macros in custom binaries.

Note: For Adams/Driveline - Because of the plugin structure of Adams/Driveline, you cannot create a custom version. You can, however, create a custom Adams/Car version, adding your own custom elements, analyses, and so on, and then load in the standard Adams/Driveline plugin.

393Customizing Your ProductOverview

directory, for use by all users, or in a private directory for personal use. You can extend this hierarchy to support multiple operating systems from one installation.

Select an entry on the left to learn how to efficiently customize the environment of your product.

Adams/CarCustomizing the Interface

394

Customizing the InterfaceAll of the menus, windows, and dialog boxes that you see in your template-based product are interface objects that you can modify easily. Most of the interface customization that you'll do involves creating new dialog boxes, modifying existing ones, or modifying menus and push buttons. Learn about saving changes to interface objects.

A template-based product stores the interface objects in its modeling database along with all the other modeling objects (such as parts, models, and markers). You access the interface objects through the Database Navigator. The objects have a defined hierarchy, which you can also view through the Database Navigator. You use the Adams/View Dialog-Box Builder to access and edit the interface objects that you can include in a dialog box, such as labels, fields, and buttons.

For an overview of all aspects of customizing an Adams product interface, including menus, and using the Dialog-Box Builder, see the Adams/View online help.

Learn more about customizing the interface:

• Naming Conventions

• Using Libraries

• Creating and Modifying Dialog Boxes

• Creating and Modifying Macros

• Creating Dialog Boxes for Templates

• Adding a Minor Role

• Adding a Major Role

• Creating Menus for Template Builder

• Automatically Loading Interface Changes

• Saving Interface Changes

Naming ConventionsWe recommend that you use a naming convention when you create and modify interface objects or macros. A naming convention reduces the chances of naming conflicts and provides a simple method for organizing files, macros, and dialog boxes.

The naming convention that we recommend is the same one that template-based products currently use. The naming convention uses the abbreviation of the object (for example, mac for macro) followed by a set of characters that identify the commands or functionality that the object executes or performs. The naming conventions for macros and dialog boxes are explained next.

• Macro naming convention - The macro naming convention uses the abbreviation mac for macro followed by the first three characters of each command in the user-entered command that executes the macro. For example, if the user-entered commands for a macro are as shown below (the first three characters are highlighted in boldface type):


395Customizing Your ProductCustomizing the Interface

acar analysis suspension single_travel submitThen, the name of the macro is:

mac_ana_sus_sin_sub• Dialog box naming convention - The naming convention for dialog boxes uses the abbreviation

dbox for dialog box followed by the first three characters of the words that identify the functionality of the dialog box. For example, if a dialog box is the interface through which a user creates a hardpoint, then the words that define its functionality are:

template_builder hardpoint create and, its name is:

dbox_tem_har_creIf, however, the dialog box performs two or more functions, as many dialog boxes do, then the dialog box name does not include the words for the function. For example, if a dialog box lets a user both create and modify a spring damper, the words that define its functionality are:

template_builder damper create/modifyand, its name is:

dbox_tem_dam

Using LibrariesWe recommend that you use libraries to store the interface objects and macros that you create. Libraries are repositories for Adams/View objects such as variables, assembly instances, macros, and dialog boxes. Using libraries allows you to easily find, retrieve, or remove specific custom objects. You can add to your template-based product as many libraries as you need. You can also have libraries within libraries.

Your template-based product stores all its objects in libraries, named as follows:

You can view the objects in the library using the Database Navigator. See About the Database Navigator.

To create libraries, execute the following command either in your .cmd file or during an interactive session. In the following command, MY_LIBRARY is the name of the library that will be created:

library create library_name=.MY_LIBRARY

Alternatively, you can add the command in the file you use to generate the site or private custom binary. The files are named as follows:

Product name: Library name:

Adams/Car .ACAR

Product name: File name:

Adams/Car acar_build.cmd


396

Learn more about those files.

Libraries can also be nested. For example:

library create library_name=.MY_LIBRARY.variableslibrary create library_name=.MY_LIBRARY.variables.torques

Creating and Modifying Dialog BoxesThe template-based products use dialog boxes to provide you with an easy way to input data or perform operations. A dialog box is usually an entry point to a custom or standard macro. The dialog box collects data from you, manipulates it, and then communicates the data to a macro or to an Adams/View function, which performs an operation using the data. Learn about macros.

Although you can set up a dialog box so that commands perform a particular task within the dialog box, we recommend that you use the dialog box as an entry point to a macro or a set of macros. By making the dialog box an entry point to a macro, you:

• Are consistent with the standard dialog boxes in template-based products.

• Take advantage of the Adams powerful macro language programming.

Note that we supply many examples of how to code dialog boxes. You can find those examples in their respective libraries. For example, acar.dboxes.

The next topics explain more about creating dialog boxes. For a general overview of creating and editing dialog boxes in Adams products, see the Adams/View online help, under the Customize tab.

• Dialog Box Objects

• Layout and Sizing of Dialog Boxes

• Commands in Dialog Boxes

• Dialog Box Error Handling

• Start, Execute, and Finish Commands

• OK, Apply, and Cancel Buttons

When you have finished modifying your dialog boxes, review the options for saving your changes and having them automatically included in your own version of your template-based product. Learn about saving dialog boxes.

Accessing Dialog Box Programming Tools

You use the Dialog Box command on the Tools menu to create and modify dialog boxes. Learn about the Dialog-Box Builder.

To view, change, and create dialog boxes, you must have expert user access to your template-based product. Learn about Setting User Access.



Dialog Box Objects

Dialog boxes are a combination of different interface objects that you can modify using the Dialog-Box Builder. These include the following:

List of Common Dialog Box Objects

The following figure shows some of the different objects. Learn more about Interface objects.

Layout and Sizing of Dialog Boxes

When you create dialog boxes, always try to minimize the amount of screen area that they take up. To be consistent with the other dialog boxes in your template-based product, you should use the size specifications listed in tables Standard Interface Dialog Box Specifications and Template Builder Dialog

The objects: Are:

Containers Subregions in a dialog box that can hold objects.

Text boxes Boxes in which you can enter information.

Pull-down menus Menus that display a list of options from which you can select only one option.

Radio boxes Toggles that set a state or mode. You can only select one state or mode.

Toggle buttons (Check boxes) Toggles that indicate an active state. You can select more than one state.

Push buttons Buttons that execute a command or set a state.

Sliders A continuous range of possible values from which you can select one value.


398

Box Specifications. The specifications also include where on the screen dialog boxes should appear, so they always appear in the same location on the screen.

We also recommend that you fix the height of dialog boxes. In most cases, only the ability to change the width of a dialog box is useful to a user because he or she may want to stretch the dialog box to see the full name of an object in a particular text box. This isn't really necessary for the height of a dialog box.

To fix the height of a dialog box, include the parameters height_minimum and height_maximum in the interface command that creates the dialog box. You must do this directly in the command file that contains the commands to create the dialog box. You cannot do this through the Dialog-Box Builder. For example, for Adams/Car, you can enter:

interface dialog modify &dialog=.ACAR.dboxes.dbox_tem_har_mod &height=150.0 height_minumum=150.0 height_maximum=150.0

When building dialog boxes, always test to ensure that the resizing attributes of each object in the dialog box are appropriate. Under Resizing in the Dialog-Box Builder, there are resizing attributes for interface objects. These attributes describe how the size of the objects on a dialog box are affected if the width or height of the dialog box changes. You should set the resizing attributes of the objects on a dialog box so that if the size of the dialog box changes, the general look of the dialog box remains the same. For example, if all the text boxes in a dialog box are right justified along the edge of the dialog box, the text boxes should all remain right justified if you increase or decrease the width of the dialog box.

Standard Interface Dialog Box Specifications

Template Builder Dialog Box Specifications

For the dialog box attribute: Set its position or size to:

Location 33, 154

Width 370

Label width 150

Label height 25

Text box width 240

For the dialog box attribute: Set its position or size to:

Location 15, 150

Width 404

Label width 150

Label height 25

Text box width 244


Commands in Dialog Boxes

All of the objects in dialog boxes can execute commands when a user acts on the object. For example, a button can execute a command when a user pushes on it, and an option choice can execute a command when a user selects that option from a pull-down menu. Having an object execute a command gives you great flexibility in how your dialog box works.

For example, you can set up your dialog box so that the commands assigned to a particular database object field can:

• Check to determine whether the object that the user selects exists in the database

• Issue a warning message if it does not exist

You can also have commands operate on other objects in dialog boxes, which causes the dialog box to change its appearance when a user makes a selection from an object. For example, when a user selects


400

an option from a pull-down menu, the dialog box changes to display objects for entering values for the selected option as shown next.

Dialog Box Error Handling

Each dialog box that you create should have a variable, named errorFlag, that represents the error condition of the dialog box. You should use the start commands of a dialog box to create the variable and set its initial value to zero or no error condition, as shown next:

variable set variable_name=$_self.errorFlag int=0

You should also reference the variable in the OK command that executes the dialog box.

For information on:

• Variables, see Using Local Variables.


• $_self, see Using Commands in Dialog Boxes.

• OK command, see OK, Apply, and Cancel Buttons.

Start, Execute, and Finish Commands

You can assign start, execute, and finish commands to higher-level objects, such as containers, and to the dialog box itself. The commands are described below. Learn more about Using Commands in Dialog Boxes.

• Start commands - Your template-based product automatically executes start commands associated with a particular interface object when that object is displayed. The start commands ensure, for example, that the dialog box is displayed properly based on the display parameters.

You should use the start commands to set an errorFlag variable to an initial value of zero, or no error condition, as shown next:

variable set variable_name=$_self.errorFlag int=0Template Builder dialog boxes usually have two possible startup parameters, which you should set up in the start commands when a dialog box is displayed. The states are:

• mode - Mode has two states, which represent the creation or modification states of a dialog box. The states are create and modify.

• object - Object used with the state modify.

An example of using the states in a start command for Adams/Car:

interface dialog display dialog=.ACAR.dboxes.dbox_tem_dam & parameters="modify", ".template1.dal_ride_damper"

• Execute commands - The execute commands of a dialog box usually work with OK and Apply buttons. You should limit the execute commands to calling macros because we recommend that you use dialog boxes as a front-end to macros. Using dialog boxes as input mechanisms to macros ensures consistency and upgradeability.

• Finish commands - Your template-based product automatically executes finish commands when an object is no longer displayed. You use them to clean up after a macro, delete unnecessary objects, such as temporary variables, and so on.

To clean up variables:

• You can use the command:

variable delete variable_name=(eval(db_children($_self, "variable")))

To clear the text boxes of a dialog box:

• You can use the command:

for var=$_self.loopobjobject(eval(db_children($_self,"graphic_interface_field")))

interface field setfield=(eval($_self,"graphic_interface_field")))

string="" execute=noend


402

Learn more at Using Commands in Dialog Boxes.

OK, Apply, and Cancel Buttons

Each dialog box in your template-based product has three standard buttons:

• OK - Executes the commands associated with the dialog box, and if it executes the command successfully, it exits the dialog box.

• Apply - Executes the commands associated with the dialog box but leaves the dialog box open so that you can execute the command again.

• Cancel or Close - Exits the dialog box without executing a command or executing only a selected command. Only dialog boxes that have an Apply button have a Close button.

Button Size

To keep your dialog boxes consistent with the dialog boxes of your template-based product, you should always keep the size of these buttons to 25 pixels high and 76 pixels wide.

Error Handling

Make sure that the commands associated with the OK button reference the dialog box error variable (errorFlag). By referencing the error variable you ensure that the dialog box will not be closed if an errorFlag was set during the execution of the dialog box commands. Because the following commands are generic, you can use them to reference the errorFlag with any dialog box:

interface dialog execute dialog=$_parent undisplay=noif condition=(!$_parent.errorFlag)

interface dialog undisplay dialog=$_parentend

Learn about error handling in dialog boxes.

Creating and Modifying MacrosA macro is a collection of single commands that enable you to perform a series of actions during a session. You write commands using the Adams/View command language.

You can modify the existing macros or add customized macros to your template-based product so your users work smarter in their template-based product. For example, in Adams/Car you can write a macro to perform a particular full-vehicle analysis. By implementing the macro, a user only needs to enter the requested values for the analysis in a dialog box and push a button. The button executes the macro, which performs the full-vehicle analysis.

You can use macros to:

• Automate repetitive procedures.

• Build general-purpose extensions, such as custom analyses, to your template-based product.

See an example of creating a macro. Although this is an Adams/Car example, you can use the general concepts to create a macro for any template-based product.


For a complete overview of creating macros, see About Creating Macros.

Learn more about adding macros to your template-based product:

• Accessing Macro Programming Tools

• Viewing Existing Macros

• Using Parameters

• Using the Echo Command

• Using Local Variables

• Macro Error Handling

When you have finished modifying your macros, review the options for saving your changes and having them automatically included in your own version of your template-based product. Learn about saving macros.

Accessing Macro Programming Tools

You use the Macro command on the Tools menu to create and modify macros. For information on the Macro command, see Editing and Creating Macros Using the Macro Editor.

To view, change, and create macros, you must have expert user access to your template-based product. Learn about Setting User Access.

Viewing Existing Macros

Because macro programming is so well developed in your template-based product, you may find it helpful to look at existing macros. Once you find a macro that most closely meets your needs, use it as the basis of customization.

As you look at the existing analysis macros within your template-based product, notice that all of them have the same basic structure.

To view existing macros:

1. From the Tools menu, point to Macro, point to Edit, and then select Modify.

The Database Navigator appears.

2. Select a macro to view.

The Macro Editor appears with the macro commands of the selected macro in the Commands text area.

Using Parameters

Parameters are placeholders for information that users provide when they execute a macro in a template-based product. You write parameters in a macro as a $ followed by the name of the parameter. Parameters let you make macros very flexible. When you create a macro, your template-based product scans the command text to identify all the parameters.


404

When you issue the command to execute the macro, you provide values for the parameter or the parameters assume default values. Your template-based product substitutes the values in place of the parameters in the macro and executes the macro commands.

You identify parameters in macros using qualifiers. Qualifiers define a parameter's type, range, count (number of values), and defaults. Learn about Parameter Qualifiers and Formats.

The following is an example of a list of parameters and their qualifiers for a macro:

! $part_name:t=string ! $location:t=location ! $type:t=string ! $orientation:t=orientation ! $mass:t=real ! $cm_location_from_part:t=location:d=0,0,0 ! $Ixx:t=real ! $Iyy:t=real ! $Izz:t=real ! $Ixy:t=real:d=0 ! $Izx:t=real:d=0 ! $Iyz:t=real:d=0 !END_OF_PARAMETERS

Using the Echo Command

The command echo=on, which is the default, is a very helpful command because it lets you review the full log of the macro execution in the command window or echoed in the acar log file.

To use the echo command, you can add the following line at the top of your macro:

default command echo=on

You will find it very helpful for debugging purposes.

Using Local Variables

You can create Adams/View variables to be used in your macros. A variable is storage location that can contain data. Once you define a variable, you can use it in any parameter, macro, or function in your template-based product.

You can define a variable as a child of any modeling object, including a macro. Defining a variable as a child of a macro is helpful in macro programming when you need to create auxiliary Adams/View variables, such as variables that call an Adams/View function or that act as a return variable from a called macro. Being able to create these variables as children of the macro results in a cleaner macro.

As a child of the macro object, the variable inherits the object's name. Therefore, the text $_SELF evaluates to the name of the parent object, which is the macro.

In addition, most often you will want to delete these auxiliary variables when the macro is finished. Creating these variables under the macro simplifies this cleanup procedure.

You can delete local variables very easily as shown next:


To use local variables:

• You should do the following:

variable set variable_name=$_self.filename &string_value="tmpfile.cmd"

To clean up local variables:

• You should do the following:

variable delete variable_name=(eval(db_children($_self,"variable")))

For more information on variables and the commands to create and clean them up, see the help in the Command Navigator associated with the command variable.

Macro Error Handling

Each macro that you create should have checks to:

• Identify inappropriate or invalid user-entered values.

• Ensure that the values specified by the user for specific parameters are realistic.

The following Adams/Car example shows how error handling works in a macro. The acar toolkit warning utility macro displays a message in a window, informing you that it encountered an error condition. The window remains open until you close it.

!---- Ensure a brake subsystem exists ---- if condition=(!subsystem_role_exists($assembly,"brake_system"))

acar toolkit warning & warning="This assembly does not have a brake subsystem!" variable set variable_name=$error_variable integer=1 return

end

You can use the acar toolkit in all template-based products.

Creating Dialog Boxes for TemplatesIn your template-based product's Template Builder, you can create your own dialog boxes to access parameters within a template that you may want to modify on a regular basis.

After you create a custom dialog box, you can attach it to a particular template. When you save the template to your default writable database, your product saves the dialog box with the template. You can also export dialog boxes as command files, and later import them into other templates.

We recommend using your template-based product's dialog boxes as a starting point to understand what you can achieve with the Dialog-Box Builder.

To create a custom dialog box for templates:

1. From the Build menu, point to Custom Gui, point to Dialog Box, and then select Create.

Your product displays an empty dialog box named dbox_1, along with the Dialog-Box Builder.


406

2. Add buttons and commands as explained in Customizing Dialog Boxes Using the Dialog-Box Builder in the Adams/View online help.

3. To close the Dialog-Box Builder, from the Dialog-Box Builder's Dialog Box menu, select Exit.

To validate your dialog box:

• From the Dialog-Box Builder's Option menu, select Test Box.

To permanently attach the dialog box to a template:

1. From the Build menu, point to Custom Gui, point to Dialog Box, and then select Attach.

2. Select << Add.

3. In the Selections dialog box, double-click the name of your dialog box. In this case, dbox_1. If you have multiple dialog boxes you want to store, repeat these steps for each dialog box.

4. Select OK.

To verify that your product stored your dialog box:

1. From the Build menu, point to Custom Gui, point to Dialog Box, and then select Display.

2. In the Selections dialog box, double-click the name of the dialog box you want to display.

Your product displays the dialog box.

To export a custom dialog box:

• From the Dialog Box Builder's Dialog Box menu, point to Export, and then select Command File.

To import a dialog box:

• To import a dialog box from a command file and attach it to a template, you must manually rename every entity in the command file for .ACAR.custom. For example:

• MY_LIBRARY.dboxes.dbox_1 becomes .ACAR.custom.dbox_1

• MY_LIBRARY.dboxes.dbox_1.field_1 becomes .ACAR.custom.dbox_1.field_1

Adding Minor RolesThe file <product_name>BS.cmd is a command file that your template-based product automatically reads in when you start a new session. You use this type of file to add a new minor or major role to your template-based product.

Learn Adding Major Roles.

Note: If you do not attach your dialog box to a template, the dialog box will be lost when you close the current session.


To add a new minor role in your template-based product:

1. Create a command file named <product_name>BS.cmd (where product_name is the abbreviation for your product, see Product Abbreviations). The contents of the command file should be similar to the contents of the following Adams/Car command file:

!--- Add a new minor role ----variable modify variable=.ACAR.variables.minor_roles &string_value=(eval(.ACAR.variables.minor_roles)),"rear2"

2. Place the command file in your home directory.

3. When your template-based product starts, it automatically reads in <product_name>BS.cmd. The command file will expand the minor roles available in your template-based product. The minor_roles variable is referenced everywhere in the underlying software and is the only change required to allow you to create new subsystems with minor roles different than the default.

4. Create a new subsystem with the new minor role. (File -> New -> Subsystem).

Notice the new entry in the Minor Role option menu.

Keep in mind the new minor role you define when you are creating/matching communicators.

Adding Major Roles The file <product_name>BS.cmd is a command file that your template-based product automatically reads in when you start a new session. You use this type of file to add a new minor or major role to your template-based product.

Learn how to add minor roles.

To add a new major role in your template-based product:

1. Create a command file named <product_name>BS.cmd (where product_name is the abbreviation for your product, see Product Abbreviations). The contents of the command file should be similar to the contents of the following Adams/Car command file:

!--- Add a new major role ----variable modify variable=.ACAR.variables.major_roles &string_value=(eval(.ACAR.variables.major_roles)),"subframe"

2. Place the command file in your home directory.

3. When your template-based product starts, it automatically reads in <product_name>BS.cmd. The command file will expand the major_roles available in your template-based product. The major_roles variable is referenced everywhere in the underlying software and is the only change required to allow you to create new subsystems with major roles different than the default.

4. Create a new template with the new major role. (File -> New).

5. Notice the new entry in the Major Role option menu.

Creating Menus for Template BuilderYou can modify your template-based product to add custom menus and buttons to the Template Builder:


408

• Submenu - You can create submenus using the Build menu. A submenu provides a container that you can use to collect push buttons (in this context, think of push buttons as options located under a submenu). For example, under the Build menu, Hardpoint is a submenu containing five push buttons/options (Modify, Table, New, Info, and Delete), as shown next.

• Push button - You can use a push button to execute a command such as displaying a dialog box or executing a macro.

When creating menus, we recommend that you first think about the structure of what you are trying to achieve. By using a hierarchical approach, you can use submenus to categorize different buttons.

In the following example we assume that you have created a custom dialog box named dbox_1. We are first going to create a submenu named Example.

To create a submenu:

1. From the Build menu, point to Custom Gui, point to Menu, point to Submenu, and then select Create.

Your product displays the Create Custom Sub-Menu dialog box.

2. Enter the label that you want to use, in this case Example, and then reference the template in which this custom menu will be stored.

3. Select OK.

Now you create a push button that resides as a child of submenu, and call the button Display. You then execute a command to display the custom dialog box, dbox_1.

To create a push button:

1. From the Build menu, point to Custom Gui, point to Menu, point to Push Button, and then select Create.

Your product displays the Create Custom Push Button dialog box.


2. Enter the label that you want to use, in this case Display.

3. Set Parent Menu to menu1, which is the submenu Example you created above. Note that as you create submenus, your product references them internally as menu1, menu2, and so on, rather than by name (in this case, Example). If you created several submenus and lost track of their names, you can use the Info command to see how your product names them: from the Build menu, point to Custom Gui, point to Menu, and then select Info.

4. The execution command is highly dependent on what you want to achieve. In this example, you want to display the custom dialog box, dbox_1, so in the Commands text box enter:

interface dialog_box display dialog_box_nam = .ACAR.custom.dbox_1

If, however, you wanted to view the front view of your model, you would enter a command similar to the following:

acar interface view_restore view_orientation = front

5. Select OK.

6. To validate that the push button works, from the Build menu, point to Example, and then select Display. Your template-based product should display your dialog box.

To change the order of your submenus:

1. From the Build menu, point to Custom Gui, point to Menu, and then select Reorder.

2. Press F1 and then follow the instructions in the dialog box help for Reorder Custom Menus.

To get information about your custom menu structure:

• From the Build menu, point to Custom Gui, point to Menu, and then select Info.

Your product displays the information in the Information window.

Automatically Loading Interface ChangesYou can configure the user interface by automatically reading one of the start-up scripts for your template-based product. Learn more.

The following is an example command file, acar_build.cmd, that customizes Adams/Car. It changes the title at the top of the Adams/Car window and reads in menu and dialog box command files that customize the Adams/Car interface. If this file is located in the start-up directory used by your template-based product, then your template-based product will read and execute it automatically. Although this file can be used to configure the product at startup, we recommend that you save either a site or private binary, as they are more efficient at startup.

You can customize the other template-based products in a similar way, using the appropriate build command files listed in table File Names. In this example, we assume that the environment variable MDI_ACAR_SITE is set.

! Adams/Car ! Copyright (C) 1995-2005 MSC.Software ! All Rights Reserved. ! !****************************************************


410

!---- Modify the window title ----interface window modify &window_name=.gui.main & title="Adams/Car: Company XYZ" & icon_label="A/XYZ"!---- Set-up libraries and variables ---- file command read file_name=(getenv("MDI_ACAR_SITE")//"/build_gui/libraries.cmd") !---- Interface Menus ---- file command read file_name=(getenv("MDI_ACAR_SITE")//"/interface/menus_int.cmd")!----Site Initialization ---- macro create macro=.ACAR.macros.acar_init_site & user_entered_command="acar toolkit initialization standard plugin=acar"

For private binaries, please substitute "acar_init_site" with "acar_init_private". You will need one 'acar toolkit initialization ...' command for each plugin you want to include in your private or site customization. If you decide to build either a site or private binary file, then you must place this file at the top level, as defined by the path in MDI_ACAR_SITE or MDI_ACAR_PRIVATE.

Saving Interface ChangesAll the changes that you make to the interface are active as long as you stay in your current session. This includes changes to interface objects and macros. You can save the changes for yourself in your private directory or you can make the changes so that all users can access them from the site directory.

There are many ways to save the changes. The most efficient is to create a private or a site binary that contains the changes. You can then instruct your template-based product to read the changes when it starts up. The following procedure summarizes the steps you would perform to save the changes in a binary. For more information, see the references noted in each step. In addition, for an overall description of creating binaries for your template-based product, see Running and Configuring Adams.

To save changes as a binary:

1. Export the new or modified macro as a command file:

• From the Tools menu, point to Macro, and then select Write.

• In the Macro Name text box, enter the name of a macro you have created or modified.

• Note that it's not mandatory to provide a file name for the macro. If you name the macro .MY_LIBRARY.macros.mac_ana_ful_tst_sub, then Adams/Car saves it as mac_ana_ful_tst_sub.cmd, automatically adding the .cmd extension.

2. Export the new or modified dialog box, as a command file:

• From the Tools menu, point to Dialog Box , and then select Modify, to open the Database Navigator. Learn About the Database Navigator.

• Select the dialog box you want to export.

Adams/Car displays the dialog box in build mode, along with the Dialog Box Builder. Learn Customizing Dialog Boxes Using the Dialog-Box Builder.

../adams_configure/master.htm


• From the Dialog Box Builder's Dialog Box menu, point to Export, and then select Command File.

Adams/Car writes a command file to your file system. The name of the resulting command file will be derived from the dialog box name. If the dialog box is named dbox_ana_ful_tst_sub, then the dialog box will be saved as dbox_ana_ful_tst_sub.cmd.

3. Create a command file, named as shown in table File Names, that reads in the command files that customize the interface. See an example of an acar_build.cmd file.

4. Add commands to that command file that automatically reads the macro and dialog box. The following would read the macro and dialog box, as saved in the steps above.

!------Read a macro-----macro read &macro_name = .MY_LIBRARY.mac_ana_ful_tst_sub &file_name = "C:\temp\mac_ana_ful_tst_sub.cmd" &user_entered = "Analysis full-vehicle test submit" &wrap_in_undo = no &create_panel = no!------Read a dialog box-----file command read &file_name = "C:\temp\abox_ana_ful_tst_sub.cmd

5. Store the file in the desired private or site file repository. Learn about private and site file repositories.

6. Create a private or a site-specific binary, including the saved interface objects, as explained in

• Creating Binary Files in the guide Running and Configuring Adams


Adams/CarIntroducing Adams/View Libraries

412

Introducing Adams/View LibrariesLibraries let you use your user-written subroutines and compiled functions. User-written subroutines and compiled functions let you tailor your template-based product to your needs and go beyond the functions you can define using macros. For more on compiled functions, see Compiled Functions in the guide, Using the Adams/View Function Builder.

You will find subroutines most helpful when the operations to be performed are heavily recursive or require file input or output.

To use your custom subroutines and functions, you create an Adams/View library. An Adams/View library extends the functionality of your template-based product during the design phase and during plotting. Using an Adams/View library, you can create compiled functions in C and use them in an Adams/View expression just as you would use standard, built-in Adams/View functions.

You register the user-written functions by calling a subroutine built into Adams/View. You must place this subroutine call in the registration subroutine supplied in source-code form in Adams/View. To automate tasks, you can write a custom Adams/View library in C. As an example, you might want to create a wavefront file that given a number of macro parameters, such as road width, length, and color, can be used to define a road graphic. In such an example, you would create a C file that when combined with some macro-wrapping code can be set up to pass parameters from the macro to your custom C routine. The following example shows five parameters (road_width, road_length, color, shell_file, error_flag) being passed to a routine named create_a_road:

variable set variable_name = $_self.generate_road &integer_value = (eval(create_a_road("$road_width", "road_length", "color", "shell_file", "error_flag" )))

If successful, this execution results in the generation of a wavefront file based on the input parameter contained in shell_file (as an example, my_road.obj).

In this case, you call a function (create_a_road) in your Adams/View library. You can set up this code to return a Boolean flag, such as 0 if it failed and 1 if it was successfully executed. You can check this flag to see if the operation was successful or not, and take action based on the result.

After you check the error flag, you can execute a read Wavefront file in the macro, specifying the shell_file file as generated by the Adams/View library:

file wavefront read & file_name = (eval($_self_shell_file)) & port_name = $assembly_ground

Learn more about Adams/View libraries:

• Requirements for Creating Custom Libraries

• Creating and Using Adams/View Libraries

Requirements for Creating Custom LibrariesTo be able to create Adams/View or Adams/Solver libraries, you must meet the following requirements:

413Customizing Your ProductIntroducing Adams/View Libraries

• To link Adams/Solver (run-time) routines, you must have a FORTRAN or C compiler.

• To link Adams/View (design-time) routines, you must have a C compiler.

You can input C or FORTRAN source files to create Adams/Solver user libraries and only C source files to create Adams/View user libraries. You must compile these subroutines before linking them with an Adams product. See the hardware and software specifications that come with your Adams product for the type of compiler you need (http://www.mscsoftware.com/support/prod_support/adams/?Q=135&Z=144&Y=174). Also refer to your compiler documentation for details.

Therefore, you can write an Adams/Solver routine in FORTRAN or C, but keep in mind that:

• The solver subroutine is expected to be in FORTRAN.

• If the solver subroutine is written in C, you must make it emulate a FORTRAN subroutine, as specified in Knowledge Base Article 8384, at http://support.adams.com/kb/faq.asp?ID=kb8384.dasp. If you write an Adams/Solver routine in C, it requires a FORTRAN header, and also requires a FORTRAN compiler (linker).

• You must have the linkers from the FORTRAN compilers to create a library, even if the subroutine is in C.

Creating and Using Adams/View LibrariesAn Adams/View library is a custom piece of C code that you can use to extend the functionality of the interface. See a simple example to automatically create a Wavefront file based on a number of input parameters from a macro.

Modifying vc_init_usr_c

You can find the file vc_init_usr.c in the distribution of Adams, under /aview/usersubs. This file provides an interface between Adams/View and user-defined functions. For this example, you'll assume that a user-defined function, named create_road, is going to be used. Following the instructions in vc_init_usr.c, you would do the following:

1. Copy vc_init_usr.c and mdi_c.h to your local working directory.

2. Modify vc_init_usr.c to suit your function (create_road). The file includes help inside comment blocks.

3. Create a C file containing the function create_road. Use the parameters that are passed to and from the function.

4. Compile the two files using the appropriate compile flags (can be found by opening an advanced session):

• On Windows:

• From the Start button, point to Programs, point to MSC.Software, point to MD Adams 2010, point to your template-based product (in this case, ACar), and then select Advanced.

• At the prompt, enter cr-acarprivate, and then press Enter.

http://www.mscsoftware.com/support/prod_support/adams/?Q=135&Z=144&Y=174

http://support.adams.com/kb/faq.asp?ID=kb8384.dasp

Adams/CarIntroducing Adams/View Libraries

414

• Press Enter again to select the default, which tells the compiler not to build debug libraries.

• Your template-based product displays the compile options.

• On UNIX:

• At the prompt, enter mdadams2010 -c acar cr-acarprivate, and then press Enter.


• Your template-based product displays the compile options.

5. To end this session, type Exit, and then press Enter.

6. Once the files have been compiled, repeat this process, this time specifying the two object files that were compiled. If everything is successful, you will now have a .dll file (.so on UNIX).

Using the Custom Adams/View Library

For the custom Adams/View library to be automatically loaded, see the notes for organizing your custom code. Once you've loaded the library into your template-based product, you should be able to reference your custom function. You can reference your function using the Function Builder or macro code.

415Customizing Your ProductIntroducing Adams/Solver Libraries

Introducing Adams/Solver LibrariesCustom Adams/Solver libraries let you use your user-written subroutines with Adams/Solver. User-written subroutines let you tailor your template-based product to your needs and go beyond the functionality provided with Adams/Solver and the specific solver functionality delivered with your product. For general information about subroutines, see:

• Using Adams/Solver Subroutines

• Running and Configuring Adams

For example, you want to create a force element that represents an aircraft landing-gear damper, then you could create a custom Adams/Solver library to define the calculations used to produce that force. Inputs to the damper might include damper velocity, damper displacement, and operating temperature. Output could be force.

To use your custom Adams/Solver subroutine, you first compile your C or FORTRAN code. You then link those files into an Adams/Solver library (*.dll or *.so (on UNIX)). The resulting file is stored in a location defined by either MDI_ACAR_SITE or MDI_ACAR_PRIVATE_DIR. When you invoke the site or private solver, the library is automatically loaded and the functions become available (dispatched using the auto-generated code in dispatch.f). A statement in the solver dataset, for the aircraft damper mentioned above, may look like this:

SFORCE/1,TRANSLATIONAL ,I = 1 ,J = 2 ,FUNCTION = USER (2001, 1, 2, 3)

where:

• 2001 is the branch ID of your sfo subroutine (your function in your subroutine would be sfo2001(par, npar)

• 1 is the ID of the variable measuring damper_velocity

• 2 is the ID of the variable measuring damper_displacement

• 3 is the ID of the variable measuring temperature

This function would provide the force to the damper element. Assuming that a subroutine named sfo2001 is included in your custom solver code, the general dispatcher will call this subroutine, pass information to the subroutine, and return the force from the subroutine.

Learn more about Adams/Solver libraries:

• Requirements for Creating Custom Libraries

• Creating and Using Adams/Solver Libraries

Requirements for Creating Custom LibrariesTo be able to create Adams/View or Adams/Solver libraries, you must meet the following requirements:


Adams/CarIntroducing Adams/Solver Libraries

416

• To link Adams/Solver (run-time) routines, you must have a FORTRAN or C compiler.

• To link Adams/View (design-time) routines, you must have a C compiler.

You can input C or FORTRAN source files to create Adams/Solver user libraries and only C source files to create Adams/View user libraries. You must compile these subroutines before linking them with an Adams product. See the hardware and software specifications that come with your Adams product for the type of compiler you need (http://www.mscsoftware.com/support/prod_support/adams/?Q=135&Z=144&Y=174). Also refer to your compiler documentation for details.

Therefore, you can write an Adams/Solver routine in FORTRAN or C, but keep in mind that:

• The solver subroutine is expected to be in FORTRAN.

• If the solver subroutine is written in C, you must make it emulate a FORTRAN subroutine, as specified in Knowledge Base Article 8384, at http://support.adams.com/kb/faq.asp?ID=kb8384.dasp. If you write an Adams/Solver routine in C, it requires a FORTRAN header, and also requires a FORTRAN compiler (linker).

• You must have the linkers from the FORTRAN compilers to create a library, even if the subroutine is in C.

Creating and Using Adams/Solver LibrariesBefore writing user subroutines, make sure you understand the concepts presented in Introducing Adams/Solver Libraries and Requirements for Creating Custom Libraries, and more importantly the requirements for the Adams/Solver dataset and the naming conventions for the subroutines and files containing subroutines. To review some of those concepts, assume that you have an Adams/Solver statement similar to the following:

REQUEST/1, FUNCTION = USER(123, ..., ...)

Then, you would need to generate a file named REQ123.f, which would contain a subroutine named req123. For example:

C Request subroutine to calculate Yaw anglesubroutine req123 (par, npar)

If you follow this convention, generating your own custom libraries should be easy.

To generate a custom library:

1. Make a list of files that you want to include in your custom Adams/Solver library.

2. Save this list in a text file named sub_list.lst. The following is an example list:

req123sfo456con789

3. Build your custom Adams/Solver Library:

• On Windows:

http://www.mscsoftware.com/support/prod_support/adams/?Q=135&Z=144&Y=174

http://support.adams.com/kb/faq.asp?ID=kb8384.dasp


• From the Start button, point to Programs, point to MSC.Software, point to MD Adams 2010, point to your template-based product (for example, Adams/Car), and then select Advanced.

• At the prompt, type cr-solverprivate, and then press Enter.


• Type @sub_list.lst to provide the list of files you want to include in your custom Adams/Solver library.

• Press Enter.

• On UNIX:

• At the prompt, type mdadams2010 -c acar cr-solverprivate, and then press Enter.


• Your template-based product displays the compiler options for the C and FORTRAN compilers. Make a note of the options.

• Type @sub_list.lst to provide the list of files you want to include in your custom Adams/Solver library.

• Press Enter.

4. Alternatively, from the command line you can create your custom library by typing the following command:


418

mdadams2010 -c acar cr-solverpr n @sub_list.lst -n

After you created the private Adams/Solver library, modify an existing Adams/Solver dataset to verify that your custom functions are working. You might find it helpful to write basic 'write' statements in your FORTRAN code to verify that the code is being executed.

Using the Dispatcher (GENDISP)Adams/Car has a unique utility for dealing with FORTRAN user subroutines called the generalized dispatcher or GENDISP. GENDISP automatically creates the necessary subroutines (REQSUB, SFOSUB, and so on) with all the branches to your routines as part of the linking of a library. The branching for each category of a subroutine (RESQUB, SFOSUB, and so on) are written into a single FORTRAN file named dispatch.f. In the topics that follow you will learn more about how this mechanism works.

Learn why you'll find it valuable to create subroutines and functions and how to create libraries that reference them:

• Overview of GENDISP

Note: • Adams/Car writes the resulting acarsolver.dll (the name of the file is dependent on your template-based product) to the directory defined by the environment variable MDI_ACAR_PRIVATE_DIR.

• If you are having difficulty building your custom code, we recommend using a DOS prompt and the command mdadams2010 acar cr-solverprivate n @sub_list.lst. This allows for output to be readable.

• If you want to create a site solver library, you can replace the command cr-solverprivate with cr-solversite. Your template-based product stores the generated library in the directory defined by the environment variable MDI_ACAR_SITE.

• Your compiled files and sub_list.lst are stored in a working directory. Your template-based product does not necessarily start in that directory. If there is a mismatch between the two directories, your template-based product is unable to locate your files and will fail.To make the working directory default to the correct location, do the following:

• On Windows:

• From the Start button, point to Programs, point to MSC.Software, point to MD Adams 2010, point to your template-based product (for example, Adams/Car), and then right-click Advanced.

• Select Properties.

• In the Start in text box, enter the location of your files (for example, c:\temp).

• On UNIX, move into the directory where sub_list.lst is located (for example, cd /usr/home/my_home/work).


• Conventions for Using GENDISP

• User-Written Subroutines that GENDISP Supports

• Adding GENDISP Support For New Subroutine Types

• Example of Using GENDISP

• How GENDISP Works

Overview of GENDISP

When you write a standard REQSUB subroutine, you often need to process output in more than one way. You might have one subroutine that computes toe, camber, and caster angle, and another that computes lateral acceleration and body sideslip angle. In your dataset you may have the following requests, which reference two user subroutines to calculate toe, camber, and caster, and in the second subroutine lateral acceleration and body sideslip.

REQUEST/111 !toe, camber, casterFUNCTION = USER(1, 1, 2, 3)REQUEST/222 !lateral acceleration, body sideslipFUNCTION = USER(2, 4, 5, 6)

The parameters of interest are USER(1, and USER(2, where the values 1 and 2 correspond to PAR(1) in the expression that follows. In your REQSUB, you must have logic to branch to the different subroutines as shown next:

IF (NINT( PAR(1)) .EQ. 1 ) THEN CALL TCCREQ( ID, TIME, PAR, NPAR, IFLAG, RESULT )

ELSE IF (NINT( PAR(1)) .EQ. 2 ) THEN CALL BSAREQ( ID, TIME, PAR, NPAR, IFLAG, RESULT )

.

.

.

In the above example, if PAR(1) is equal to 1 (as defined by REQUEST/111), then the subroutine TCCREQ is called. Likewise, if PAR(1) is equal to 2 (as defined by REQUEST/222), then the subroutine BSAREQ is called.

Each time you add a new subroutine, you must rewrite your REQSUB to call that subroutine. If your company has a standard REQSUB, you have to create a local version for yourself and then add your subroutines to it.

With the template-based products, however, if you follow a simple naming convention for your user-written subroutines, GENDISP automatically creates a REQSUB, SFOSUB, and so on, with all the branches to your routines as part of the linking of a library. GENDISP places these subroutines in an automatically generated file, named dispatch.f.

For example, if you rename the subroutine TCCREQ to REQ001 and the subroutine BSAREQ to REQ002, then GENDISP creates a REQSUB for you with branches to REQ001 and REQ002 as shown next:

IF (NINT( PAR(1)) .EQ. 1 ) THEN CALL REQ001( ID, TIME, PAR, NPAR, IFLAG, RESULT )


420

ELSEIF (NINT( PAR(1)) .EQ. 2 ) THEN CALL REQ002( ID, TIME, PAR, NPAR, IFLAG, RESULT )

.

.

.

Using GENDISP makes the generation of dispatcher routines a fully automated process, allowing you to concentrate primarily on the content of your solver subroutines.

Conventions for Using GENDISP

To use GENDISP correctly, you must do the following:

• Name your user subroutines using the convention that the first three characters must be the same as the calling user subroutine and the last three characters of the subroutine name must be numbers. For example, the subroutine called by a REQSUB, must be named REQ001, REQ002, and so on. Another example would be naming GFORCE user subroutines called from a GFOSUB names like GFO241, GFO534, and so on.

• Name your source code or object code files according to this convention. For GENDISP to work, the source code or object code files must have the same root name as the subroutine (for example, req001.f or req001.o). Note that GENDISP ignores case. Therefore, REQ001.f is the same as req001.f or ReQ001.f. GENDISP generates branches based on the root file name. GENDISP does not examine the contents of a file for names matching the convention.

• When invoking a user subroutine from your Adams model, make sure that the first user parameter matches the subroutine you want to call. For example, the following sensor statement generates a call to SEN743:

SENSOR/1, FUNC=USER(743, .......)\ Remember to always reserve the first parameter for branching when writing your user subroutines.

• Number all your routines in the 001 to 799 range (for example, REQ300 and SFO465). The range 900+ is reserved for standard Adams user subroutines.

User-Written Subroutines that GENDISP Supports

GENDISP supports the following Adams/Solver user-written subroutines. Learn about subroutines.

Adams/Solver User-Written Subroutines that GENDISP Supports

Name: Description:

CONSUB Control command

COUSUB Coupler subroutine and partial derivatives

COUXX Coupler first partial derivatives subroutine (CXX100)

COUXX2 Coupler second partial derivatives subroutine (CXD100)

CURSUB Curve statement


GENDISP supports the following Adams/Car user-written subroutine types:

Adams/Car Subroutine Types That GENDISP Supports

Adams/Tire now supports dynamic loading (dispatching) of tire (TYRSUB) and road contact (ARCSUB) subroutines. Support for standard driver interface (SDISUB) for lack of usage.

DIFSUB Differential equation statement

DMPSUB Modal damping subroutine

FIESUB Field statement

GFOSUB Gforce statement

GSESUB General state equation subroutine

Adams/Car provides generic GSEYU, GSEXU, GSEXX and GSEYX subroutines that numerically difference a GSE subroutine. The general dispatcher, however, does not provide support for the revised GSE implementation using the GSE_DERIV, GSE_UPDATE, GSE_OUTPUT, and GSE_SAMP subroutines.

MFORCE Modal force subroutine

MOTSUB Motion statement

REQSUB Request statement

SENSUB Sensor statement

SFOSUB Sforce statement

TIRSUB Tire statement subroutine (to be discontinued)

UCOSUB Ucon (user constraint) statement

VARSUB Variable statement

VFOSUB Vforce statement

VTOSUB Vtorque statement

Name: Description:

BRASUB Brake demand

STRSUB Steering demand

THRSUB Throttle demand

Name: Description:


422

Adding GENDISP Support For New Subroutine Types

To add support for a new subroutine type, you modify the file dispatch.dat to add the new type. You can find a copy of dispatch.dat in the directory install_dir/product_name/dispatch.dat, where install_dir is the directory in which you installed your template-based product and product_name is acar, aengine, aircraft, or arail, according to the product you are using.

The file, dispatch.dat, is a TeimOrbit format file containing a block for each supported subroutine type and follows these rules:

• Block names are limited to three characters. For example, [MYU] is valid, but [MYUT] is not.

• Branching is always based on PAR(1) in the generated source code. So PAR must either be an array passed to the user subroutine as in REQSUB or PAR must be created using the (CODE_BEFORE_BRANCH) option as Example of Using GENDISP.

• Code in the (CODE_BEFORE_BRANCH) sub-block is output literally to the generated source code, and must follow FORTRAN's strict formatting rules. For example, executable code on a line must be indented six spaces.

For example, the block for REQSUBs looks like: $******************************************** [REQ] (PARAMETERS) {type name}'INTEGER' 'ID' 'DOUBLE PRECISION' 'TIME' 'DOUBLE PRECISION' 'PAR(*)' 'INTEGER' 'NPAR' 'LOGICAL' 'IFLAG' 'DOUBLE PRECISION' 'RESULT(8)'$********************************************

With this block in dispatch.dat and given a list of files names containing req900, req901, and req221, GENDISP would create the following source code in the file dispatch.f:

Cccccccccccccccccccccccccccccccccccccccccccccccccccc subroutine reqsub( ID,

& TIME, & PAR,

& NPAR,& IFLAG,& RESULT )

C This is a dispatcher routine written by gendisp INTEGER ID DOUBLE PRECISION TIME DOUBLE PRECISION PAR(*) INTEGER NPARLOGICAL IFLAGDOUBLE PRECISION RESULT(8)

C Local variablescharacter*(80) errmsgIF ( NINT(PAR(1)).EQ.900 ) THEN

CALL req900 ( ID,


& TIME,& PAR,& NPAR, & IFLAG, & RESULT )

ELSE IF ( NINT(PAR(1)).EQ.901 ) THENCALL req901 ( ID,

& TIME, & PAR, & NPAR,& IFLAG,& RESULT )

ELSE IF ( NINT(PAR(1)).EQ.221 ) THENCALL req221 ( ID,

& TIME, & PAR, & NPAR, & IFLAG, & RESULT )

ELSE WRITE (ERRMSG,'(A,I4.4)')

& 'Error in dispatcher subroutine reqSUB: InvalidPAR(1): ',

& NINT( PAR(1) ) CALL ERRMES( .TRUE., ERRMSG, 0, 'STOP')

ENDIFRETURN

END

Each block for a subroutine in dispatch.dat must contain a (PARAMETERS) sub-block that defines the subroutine parameter types. Optionally, a block may contain a (CODE_BEFORE_BRANCH) sub-block as illustrated in the example MYUSUB shown in Example of Using GENDISP.

Using GENDISP

The following procedure is only applicable if you want to extend the libraries that GENDISP dispatches. Here we provide an overview of how to test additions to the dispatch.dat file. The result of this procedure should be a fully populated dispatch.f file, which you can examine to verify that valid subroutines have been written. In normal circumstances, this procedure should not required because this process is automated by the acarcom and acarsolvercom scripts. We provide this procedure as a means to validate that you correctly modified the dispatch.dat file.

GENDISP is invoked when linking private or site libraries. A list of standard template-based product file names, plus file names you supply, are passed to GENDISP. GENDISP examines the list of files for names matching the supported subroutine types given in the file dispatch.dat. For each matching name, GENDISP creates a branch in the appropriate user subroutine and outputs the source code file dispatch.f to the working directory.

The file dispatch.f can contain multiple subroutines, but only one of each type (for example, one REQSUB or one CURSUB). The acarcom and acarsolvercom scripts include dispatch.f when linking. The files dispatch.f and dispatch.o are left in the working directory so you can look at them.


424

For testing or other purposes, you can execute GENDISP yourself. You can find GENDISP at the following location, where install_dir is the installation directory, and product_name is the name of your template-based product:

$install_dir/$product_name/$MDI_CPU/gendisp

For example, the location of GENDISP might be:

/usr/mdi12/acar/irix32/gendisp

You invoke GENDISP with the following arguments:

gendisp file.lst dispatch.f dispatch.dat where:

• file.lst - File containing a list of user subroutine filenames for GENDISP processing.

• dispatch.f - Source code file name output by GENDISP.

• dispatch.dat - TeimOrbit format file defining the supported subroutine types and their parameter lists.

Example of Using GENDISP

The following example uses GENDISP to generate a MYUSUB that branches to subroutines named myu532, myu253, and so on. It also branches to these subroutines based on an integer argument named SWITCH.

SUBROUTINE MYUSUB( SWITCH, NDPAR, DPAR, VECTOR ) C C GLOBAL VARIABLES C

INTEGER SWITCH INTEGER NDPAR DOUBLE PRECISION DPAR(NDPAR) DOUBLE PRECISION VECTOR(3)

C C LOCAL VARIABLES C

CHARACTER*(80) ERRMSG INTEGER PAR(2)

C PAR(1) = SWITCH IF ( NINT(PAR(1)).EQ.532 ) THEN

CALL MYU532 ( SWITCH, NDPAR, DPAR, VECTOR ) ELSE IF ( NINT(PAR(1)).EQ.253 ) THEN

CALL MYU253 ( SWITCH, NDPAR, DPAR, VECTOR ) ELSE

WRITE (ERRMSG,'(A,I4.4)') & 'ERROR in dispatcher subroutine MYSSUB: invalid switch:',& NINT( PAR(1) )

CALL ERRMES( .TRUE., ERRMSG, 0, 'STOP') ENDIF RETURN


END

To dispatch.dat, you add a block for MYSSUB that looks like the following:

$********************************************[MYU] (PARAMETERS) {type name} 'INTEGER' 'SWITCH' 'INTEGER' 'NDPAR' 'DOUBLE PRECISION' 'DPAR(NDPAR)' 'DOUBLE PRECISION' 'VECTOR(3)' (CODE_BEFORE_BRANCH) {code} ' INTEGER PAR(2)' ' PAR(1) = SWITCH' $********************************************

The code GENDISP generates for MYUSUB looks a little different then the example above, but functions in the same way:

Ccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccc subroutine myusub( SWITCH,

& NDPAR,& DPAR

, & VECTOR )C This is a dispatcher routine written by gendisp

INTEGER SWITCHINTEGER NDPARDOUBLE PRECISION DPAR(NDPAR)DOUBLE PRECISION VECTOR(3)

C Local variablescharacter*(80) errmsgINTEGER PAR(2)PAR(1) = SWITCHIF ( NINT(PAR(1)).EQ.532 ) THEN

CALL myu532 ( SWITCH,& NDPAR,& DPAR,& VECTOR )ELSE IF ( NINT(PAR(1)).EQ.253 ) THEN

CALL myu253 ( SWITCH,& NDPAR,& DPAR,& VECTOR )ELSE

WRITE (ERRMSG,'(A,I4.4)') & 'Error in dispatcher subroutine myuSUB: InvalidPAR(1): ',& NINT( PAR(1) )

CALL ERRMES( .TRUE., ERRMSG, 0, 'STOP') ENDIF

RETURNEND

Adams/CarUtility Functions

426

Utility FunctionsThis topic lists utility functions that help you extend the Adams/View macro language. The functions help you access information that is not easy to access using the standard Adams/View macro language. You can use the utility functions in macros and in dialog boxes.

The following functions are used by the template-based products. To see information on all functions available in the Function Builder, see the Function Builder online help.

• Units-Conversion Functions

• String Functions

• Database Functions

• File Functions

• Database Lookup Functions

• Miscellaneous Functions

Units-Conversion FunctionsThe units-conversion functions convert an input value to a different unit system. The units-conversion functions are:

• convert_from_units

• convert_units

• convert_to_radians

• units_to_mks

convert_from_units

Definition

convert_from_units converts the input value from a unit type to the equivalent modeling units. It accepts any valid units string (for example, mm, newton, or inch) for the unit type. It returns the converted value.

Format

REAL convert_from_units (STRING from_units, REAL in_value)

Arguments

from_units A string specifying the current units of the argument in_value.

in_value A real number to be converted.

../adams_view_fn/master.htm

427Customizing Your ProductUtility Functions

Examples

The following example converts the current length units, which are in inches (inch), to millimeters (mm):

variable set variable=units_convert & real_value=(eval(CONVERT_FROM_UNITS("inch", 1.0)))

units_convert = 25.4

convert_units

Definition

convert_units returns the conversion factor necessary to convert a value from the current units (from_units) to the desired units (to_units). It accepts any valid units string (for example, mm, newton, or inch) for the units strings. The units should be equivalent modeling units of length, force, mass, time, or angle.

Format

REAL convert_units (STRING from_units, REAL to_units)

Arguments

Examples

The following example returns the conversion factor necessary to convert miles to millimeters:

variable set variable=convert_factor & real_value=(CONVERT_UNITS( "mile" , "mm" ))

convert_factor = 1.609344E+06

convert_to_radians

Definition

convert_to_radians converts an angle from degrees to radians. You specify the input value in current modeling angular units.Format

REAL convert_to_radians (REAL in_value)

Arguments

from_units A string specifying the current units.

to_units A string specifying the desired units.

in_value A real number to be converted.


428

Examples

The following example converts the current modeling angular units, which are in degrees, to radians:

variable set variable=angle_radians & real_value=(CONVERT_TO_RADIANS(90))

angle_radians = 1.5707963268

units_to_mks

Definition

units_to_mks returns the conversion factor from user units to database units (meters, kilograms, seconds, radians, or mks).Format

REAL units_to_mks (INTEGER units)

Arguments

Examples

The following example returns the conversion factor necessary to change degrees to database units:

variable ser variable=myvar1 & real_value=90.0 units=angle

variable set variable=myvar2 & real_value=(UNITS_TO_MKS( myvar1.units ))

myvar2 = 1.7453...E-02

String FunctionsThe string functions allow you to manipulate character strings. The string functions are:

• str_assembly_class

• str_char_swap

• str_filename

• str_model_class

• str_prefix

• str_remove

• str_replace

• str_typecheck

units An integer value.


str_assembly_class

Definition

str_assembly_class returns the assembly class of an assembled model. Your template-based product stores the returned information in the assembly_class variable under all assemblies. For Adams/Car, typical assembly classes include suspension and full_vehicle. You can also extend the assembly classes.

If no assembly variable exists within the assembled model, str_assembly_class returns an empty string.

Format

STRING str_assembly_class (OBJECT assembled_model)

Arguments

Examples variable set variable=current_class &

string_value=(STR_ASSEMBLY_CLASS(.susp_assy)) current_class = "suspension"

str_char_swap

Definition

str_char_swap changes a single character in a string (object_name) at a particular location (index) to another character string. It changes the characters as specified in swap_str.

str_char_swap compares the strings and changes them only in the string following the last . in object_name. In addition, swap_str must be two or more characters long and contain an even number of characters.

The first half of swap_str determines the characters to be changed ("from characters") and the second half of swap_str determines the characters to which the characters are to be changed ("to characters"). If str_char_swap does not change any characters, it returns the original object_name string.

Format

STRING str_char_swap (STRING object_name, STRING swap_str, INT index)

Arguments

assembled_model Name of the assembled model.

object_name A string that usually contains an object's name.

swap_str A string that describes the rules for character changing.

index An integer that specifies the index of the character to be changed.


430

Examples

In the following Adams/Car example, lrrl is the string that defines what should be changed. The first half of the string (lr) represents the valid "from characters." The second half of the string (rl) represents the "to characters."

If the example finds one of the "from characters" at position 3 in the string ._front_susp.ground.hpl_lca_front, it replaces the "from characters" with the corresponding "to characters." In this example, l would change to r.

variable set variable=symmetric_name &string_value=(STR_CHAR_SWAP("._front_susp.ground.hpl_lca_front",

"lrrl", 3)) symmetric_name = "._front_susp.ground.hpr_lca_front"

str_filename

Definition

str_filename strips an input string (in_str) to a base file name (with extension) and then substitutes a new string (new_str) for the old string (old_str) if the old string exists in the base name. If old_str occurs more than once in the input string, str_filename only replaces the last occurrence.

Format

STRING str_filename (STRING in_str, STRING old_str, INT new_str)

Arguments

Examples variable set variable=base_filename &

string_value=(STR_FILENAME("/usr/car.cdb/test.tpl", "tpl","sub"))base_filename = "test.sub"

str_model_class

Definition

str_model_class returns a model's model class. This information is stored in the model_class variable under all models. If no such variable exists within the model, str_model_class returns an empty string. Typical model classes include template, subsystem, and assembly.

in_str The input string, which is usually a file path.

old_str The string to be replaced.

new_str The string to replace old_str.


Format

STRING str_model_class (OBJECT model)

Arguments

Examples variable set variable=current_class &

string_value=(STR_MODEL_CLASS(._front_susp)) current_class = "template"

str_prefix

Definition

str_prefix returns the generic prefix for a given string (object_name). The length of the return string is always four characters long. str_prefix also pares the input down to only the string following the last . in object_name.

Format

STRING str_prefix (STRING object_name)

Arguments

Examples variable set variable=name_prefix &

string_value=(STR_PREFIX("._front_susp.ground.hpl_lca_outer")) name_prefix = "hps_"

str_remove

Definition

str_remove trims an input string (in_str) by removing a string (begin_str) from the beginning of in_str and a string (end_str) from the end of in_str.

str_remove removes begin_str before removing end_str so if the beginning and ending string in in_str overlap, str_remove only removes begin_str.

Format

STRING str_remove (STRING in_str, STRING begin_str, STRING end_str)

model A model entity.



432

Arguments

Examples variable set variable=trim_string &

string_value=(STR_REMOVE("abcdef", "ab", "ef")) trim_string = "cd" variable set variable=trim_string &

string_value=(STR_REMOVE("abcdef", "", "ef")) trim_string="abcd"

str_replace

Definition

str_replace replaces a string (old_str) with a new string (new_str) in the string in_str. If there are multiple occurrences of old_str, str_replace replaces the last occurrence.

Format

STRING str_replace (STRING in_str, STRING old_str, STRING new_str)

Arguments

Examples variable set variable=other_filename &

string_value=(STR_REPLACE("/usr/car.cdb/test.tpl", "test","junk")) other_filename = "/usr/car.cdb/junk.tpl"

str_typecheck

Definition

str_typecheck returns a 1 if a list of characters (type) matches the third character in the base name of an object's name (object_name). str_typecheck always pares down the input to only the string following the last . in object_name.

You can specify more than one character in type.

in_str The input string.

begin_str A string to be removed from the beginning of in_str.

end_str A string that defines where to truncate the input string.

in_str The input string.

old_str The string to be replaced.

new_str The string to replace old_str.


Format

STRING str_typecheck (STRING object_name, STRING type)

Arguments

Examples variable set variable=check_type &

string_value=(STR_TYPECHECK("._front_susp.ground.hpl_lca_outer","ls")) check_type = 1 variable set variable=check_type &

string_value=(STR_TYPECHECK("._front_susp.ground.hpl_lca_outer","r"))check_type = 0

Database FunctionsThe database functions let you manage and access the databases of your template-based product. The database functions are:

• cdb_alias2path

• cdb_path2alias

• cdb_input2base

• cdb_input2ext

• cdb_input2file

• cdb_input2path

• cdb_input2full

• cdb_search_file

• cdb_runtime_path_port

cdb_alias2path

Definition

cdb_alias2path returns the full path associated with a given table path alias or cdb_name. If cdb_alias2path does not find the full table path corresponding to the alias, it returns the input string. By returning the input string, you can input normal path names and filenames, and cdb_alias2path returns them without modification.


type A list of characters to match. Allowed characters are l, r, and s.


434

Format

STRING cdb_alias2path (STRING path_alias)

Arguments

Examples

This example finds the file system path associated with database prototype:

variable set variable=a2p & string_value=(eval(cdb_alias2path("prototype")))

a2p = "/local/proto.cdb"

cdb_path2alias

Definition

cdb_path2alias returns the path alias associated with a given table path alias or cdb_name. If cdb_path2alias does not find a path alias corresponding to the full path name, it returns the input string. By returning the input string, cdb_path2alias allows you to enter normal path names and filenames, and returns them without modification.

Format

STRING cdb_path2alias (STRING path)

Arguments

Examples

This example finds the database alias associated with database:

variable set variable=p2a & string_value=(eval(cdb_path2alias("/local/proto.cdb")))

p2a = "prototype"

path_alias Alias used for internal reference to database.

Note: When comparing strings, UNIX is case sensitive. Windows is not.

path File system path of the database.


cdb_input2base

Definition

cdb_input2base returns the base name of a file (input_name). It strips the input_name of both its file system path prefixes and extension or suffix, if any.

Format

STRING cdb_input2base (STRING input_name)

Arguments

Examples

This example finds the base name for the file /local/proto.cdb/bushings.tbl/my_bush.bus:

variable set variable=i2b & string_value(eval(cdb_input2base("/local/proto.cdb/bushings.tbl/m

y_bush.bus"))) i2b = "my_bush"

cdb_input2ext

Definition

cdb_input2ext returns the extension or suffix of a file (input_name). It returns an empty string if it finds no extension

Format

STRING cdb_input2ext (STRING input_name)

Arguments

Examples

This example finds the extension for the file /local/proto.cdb/bushings.tbl/my_bush.bus:

variable set variable=i2e &string_value=(eval(cdb_input2ext("/local/proto.cdb/bushings.tbl/my

_bush.bus")))i2e = "bus"

input_name File system path to be converted to base name.

input_name File system path to be converted to extension.


436

cdb_input2file

Definition

cdb_input2file returns the filename contained in input_name. cdb_input2file strips input_name of any file system path prefix and returns the result.

Format

STRING cdb_input2file (STRING input_name)

Arguments

Examples

This example finds the filename for the file /local/proto.cdb/bushings.tbl/my_bush.bus:

variable set variable=i2file &string_value=(eval(cdb_input2file("/local/proto.cdb/bushings.tbl/my_bush

.bus")))i2file = "my_bush.bus"

cdb_input2path

Definition

cdb_input2path returns the file system path prefix of a filename. If the path prefix is not present, cdb_input2path returns an empty string.

Format

STRING cdb_input2path (STRING input_name)

Arguments

Examples

This example finds the file system path prefix for the file /local/proto.cdb/bushings.tbl/my_bush.bus:

variable set variable=i2p &string_value=(eval(cdb_input2path("/local/proto.cdb/bushings.tbl/my_bush

.bus")))i2p = "/local/proto.cdb/bushings.tbl"

input_name File system path to be converted to filename.

input_name Filename to be converted into file system path prefix.


cdb_input2full

Definition

cdb_input2full returns the file system path of a filename containing a database alias. If cdb_input2full finds no database alias present, it returns the input string.

Format

STRING cdb_input2full (STRING input_name)

Arguments

Examples

This example finds the file system path for the file mdids://prototype/bushings.tbl/my_bush.bus:

variable set variable=i2full &string_value=(eval(cdb_input2full("mdids://prototype/bushings.tbl/

my_bush.bus")))i2full = "/local/proto.cdb/bushings.tbl/my_bush.bus"

cdb_search_file

Definition

cdb_search_file returns the file system path of the input file (filename). First, it checks to determine if the filename as input corresponds to an existing file. It expands any database alias to its corresponding file system path, and looks for the filename at the resultant location. If it finds no file, it removes any file system path prefix from the filename, and begins its to search the different databases in the specified search order.

Remember that search order may be important. If two identically named files exist in different databases, the search order determines which of these files cdb_search_file finds and returns.

cdb_search_file returns an empty string if it does not find the requested filename after searching the databases.

Format

STRING cdb_search_file (STRING class_name, STRING filename, INT level)

input_name Filename with database alias to be converted to file system path.


438

Arguments

Examples

This example finds the file system path for file my_bush.bus:

variable set variable=sfile & string_value=(eval(cdb_search_file("bushing","my_bush.bus",1)))

sfile="/local/proto.cdb/bushings.tbl/my_bush.bus"

cdb_runtime_path_port

Definition

cdb_runtime_path_port returns the filename of the input string (input_name) converted to the appropriate operating system format. You will find cdb_runtime_path_port useful when you are sharing filenames between UNIX and Windows file systems. It also lets you use a database alias instead of a full file system path.

Format

STRING cdb_runtime_path_port (STRING input_name)

Arguments

Examples

This example returns the Windows version of the filename for the file mdids://prototype/bushings.tbl/my_bush.bus:

variable set variable=rpp & string_value=(eval(cdb_runtime_path_port(“mdids://prototype/bushings.tbl/

my_bush.bus”))) rpp = "mdids://prototype\bushings.tb\my_bush.bus"

File FunctionsThe file functions return information about the major and minor roles of templates and subsystems:

• template_hdr_major_role

class_name The type class name for the table in which to search for the file. It is defined in the configuration files.

filename The filename, either with or without any path prefix, to be found.

level The level in the search list at which to start searching. The value is usually 1, which indicates a full search.

input_name File system path to be converted to an operating-system specific filename.


• subsystem_hdr_major_role

• subsystem_hdr_minor_role

template_hdr_major_role

Definition

template_hdr_major_role returns the major role of a template. Your template-based product stores the major role information in the header information of all template files (.tpl). template_hdr_major_role automatically opens a template file, retrieves the information from the file header, and closes the file.

Format

STRING template_hdr_major_role (STRING filename)

Arguments

Examples

This is an example of the header information that is stored in an Adams/Car template file:

$------------------------TEMPLATE_HEADER----------------------$ [TEMPLATE_HEADER] MAJOR_ROLE = 'suspension'TIMESTAMP ='1999/02/04,13:13:38'HEADER_SIZE = 5

The following example returns the major role of a template, which it obtains from the header information shown above:

variable set variable=tpl_major_role & string_value=(TEMPLATE_HDR_MAJOR_ROLE

("mdids://shared/template.tbl/_dbl_wish.tpl"))tpl_major_role = "suspension"

subsystem_hdr_major_role

Definition

subsystem_hdr_major_role returns the major role of a subsystem. Your template-based product stores the major role information in the header information of all subsystem files (.sub). subsystem_hdr_major_role automatically opens a subsystem file, retrieves the information from the file header, and closes the file.

Format

STRING subsystem_hdr_major_role (STRING filename)

filename String that contains the full path of the template file.


440

Arguments

Examples

This is an example of the header information that is stored in an Adams/Car subsystem file:

$--------------------------SUBSYSTEM_HEADER -----------------------$[SUBSYSTEM_HEADER]TEMPLATE_NAME = ’mdids://shared/templates.tbl/_double_wishbone.tpl’MAJOR_ROLE = ’suspension’MINOR_ROLE = ’front’TIMESTAMP = ’1999/02/04,17:18:18’

The following example returns the major role of an Adams/Car subsystem, which it obtains from the header information shown above:

variable set variable=sub_major_role & string_value=(SUBSYSTEM_HDR_MAJOR_ROLE("mdids://shared/subsystem.tbl/

front_susp.sub"))sub_major_role = "suspension"

subsystem_hdr_minor_role

Definition

subsystem_hdr_minor_role returns the minor role of a subsystem. Your template-based product stores the minor role information in the header information of all subsystem files (.sub). subsystem_hdr_minor_role automatically opens a subsystem file, retrieves the information from the file header, and closes the file.

Format

STRING subsystem_hdr_minor_role (STRING filename)

Arguments

Examples

This is an example of the header information that is stored in an Adams/Car subsystem file:

$------------------------SUBSYSTEM_HEADER ----------------------$[SUBSYSTEM_HEADER]TEMPLATE_NAME = ’mdids://shared/templates.tbl/_double_wishbone.tpl’MAJOR_ROLE= ’suspension’MINOR_ROLE= ’front’TIMESTAMP= ’1999/02/04,17:18:18’

filename String that contains the full path of the subsystem file.

filename String that contains the full path of the subsystem file.


The following example returns the minor role of an Adams/Car subsystem, which it obtains from the header information shown above:

variable set variable=sub_minor_role &string_value=(SUBSYSTEM_HDR_MINOR_ROLE("mdids://shared/subsystem

.tbl/front_susp.sub")) sub_minor_role = "front"

Database Lookup FunctionsThe database lookup functions find specified models or subsystems based on their classes or roles during a session.

• model_class_exists

• subsystem_lookup

• subsystem_role_exists

model_class_exists

Definition

model_class_exists lets you easily determine if a model of a particular model class exists in the current session. model_class returns a 1 if a model of the specified model class exists.

Your template-based product stores the model class information in the model_class variable under all models. Typical model classes include template, subsystem, and assembly.

Format

INT model_class_exists (STRING model_class)

Arguments

Examples if condition=(model_class_exists("assembly") == 0)

! No Assemblies !end

subsystem_lookup

Definition

subsystem_lookup returns the subsystem contained in the assembled model with the specified major and minor role. If no such subsystem exists, subsystem_lookup returns no object or NONE.

model_class String containing the model class.


442

Format

OBJECT subsystem_lookup (OBJECT model, STRING major_role, STRING minor_role)

Arguments

Examples variable set variable=front_susp_subsystem &

object_value=(eval(SUBSYSTEM_LOOKUP(.susp_assy, "suspension","front")))front_susp_subsystem = .susp_assy.TR_Front_Suspension

subsystem_role_exists

Definition

subsystem_role_exists lets you easily determine if a subsystem of a particular role exists in an assembled model. subsystem_role_exists returns a 1 if the assembled model contains such a subsystem. Your template-based product stores the role information in the role variable that exists in each subsystem.

Format

INT subsystem_role_exists (OBJECT model, STRING role)

Arguments

Examples if condition=(subsystem_role_exists(.fveh_assembly, "brake_system")== 0)

! No Brakes !end

Miscellaneous FunctionsThis topic lists utility functions that help you extend the Adams/View macro language. The functions help you access information that is not easy to access using the standard Adams/View macro language. You can use the utility functions in macros and in dialog boxes.

model Name of the assembled model.

major_role String containing the major role to look up.

minor_role String containing the minor role to look up.


role String containing the role to look up.


• ac_info_mass

ac_info_mass

Definition

ac_info_mass computes the aggregate mass of the assembly.

Format

ac_info_mass(OBJECT model)

Arguments

Examples variable set variable_name=total_mass &

real_value=(EVAL(ac_info_mass(.model_name)))

Organizing Custom CodeYou can set up private and site repositories for storing:

• Binaries that contain interface changes and macros

• Libraries that contain linked subroutines and compiled functions

For example, when a group of users needs to access the same information or are working on the same project, you can create a custom site repository. By having a site repository, they can share site-specific versions of the template-based product and configuration files.

Also, a private repository is a convenient way for a single user to create several custom versions of a template-based product or to work on different projects. Private locations let you create an unlimited number of site binaries and libraries.

In the site or private repository, your template-based product creates a directory structure that mimics the installation directory structure. The directory contains subdirectories for each platform for which you created a binary or a library.

You control the location of the private repository using the privateDir setting. The privateDir setting tells Adams where to locate the appropriate files and where to store the resulting files. The default location of the private repository is as follows:



444

Default Location of Private Repository

Where $HOME represents your user home directory when you log on to your computer.

Defining Site Repositories

To define the site repository in UNIX:

• In Adams Toolbar, change the siteDir setting in the Adams/Car preferences. For example, change it to:

/usr/people/someone/acar_site• You can also change the siteDir setting using the Registry Shell Tool from the command line.

For example, at the command line enter:

mdadams2010 -c rtool set /MDI/ACar/Preferences/siteDir /usr/people/someone/acar_site

To define the site repository in Windows:

1. From the Start menu, point to Programs, point to MSC.Software, point to MD Adams 2010, and then select Adams - Settings.

2. Double-click the name of your product (ACar).

3. Select Preferences.

4. To the right of siteDir, in the Value column, enter (or right-click to browse for) a directory path, such as d:\acar_custom.

5. Select Apply or OK.

Defining Private Repositories

To define the private repository in UNIX:

• In Adams Toolbar, change the privateDir setting in the Adams/Car preferences. For example, change it to:

/usr/people/someone/new_private• You can also change the privateDir setting using the Registry Shell Tool from the command

line. For example, at the command line enter:

Product name: File name:

Adams/Car $HOME/acar_private

Note: The following procedures show how you can define the site and private repositories for Adams/Car. Follow the same basic procedures to define the site repository for your template-based product.


mdadams2010 -c rtool set /MDI/ACar/Preferences/privateDir /usr/people/someone/new_private

To define the private repository in Windows:

1. From the Start menu, point to Programs, point to MSC.Software, point to MD Adams 2010, and then select Adams - Settings.

2. Double-click the name of your product (ACar).

3. Select Preferences.

4. To the right of siteDir, in the Value column, enter (or right-click to browse for) a directory path, such as d:\acar_custom.

5. Select Apply or OK.

For more information on the directories, creating the binaries and libraries, and the Adams Toolbar, see Running and Configuring Adams.


Adams/CarExample Four-Post Analysis

446

Example Four-Post AnalysisAlthough this is an Adams/Car example, you can use the general concepts presented here to customize any template-based product.

• Building and Running an Analysis: Teaches the expert user how to build and run a full-vehicle analysis with the four-post test rig.

• Creating and Running a Macro: Introduces the concepts of creating and running a macro for the scenario given above.

Setting Up and Running an AnalysisLearn about building and running an analysis:

• Extracting the Files

• Test Description

• Test Rig Description

• Loading an Assembly with the Test Rig

• Running a Test

Extracting the Files

To get started with the example four-post test rig, extract the files located in the directory install_dir/acar/examples/fourpost (for example, C:\MSC.Software\MD_Adams\2010\acar\examples\fourpost). Then, use the file acar_build.cmd to create a site binary that contains the test rig and corresponding macros. To create a site binary file that contains the appropriate test rig and analysis macro files, you must perform the following steps:

1. Set the following environment variable to the location where your files are stored: MDI_ACAR_SITE.

• On Windows, it might look like: C:\MSC.Software\MD_Adams\2010\acar\examples\fourpost.

• On UNIX, it might look like: /usr/mdadams2010/acar/examples/fourpost.

Make sure you have write permissions within this directory.

2. Build the Adams/Car site binary file as follows:

• On Windows: From the Start menu, point to Programs, point to MSC.Software, point to MD Adams 2010, and then select Adams - Command. In the command window, type acar; cr-sitebin

• On UNIX: Type mdadams2010; type acar, and then type cr-sitebin

Adams/Car automatically executes acar_build.cmd and builds all the appropriate entities and libraries into a site version of the Adams binary file.

3. To run the site binary file, follow the steps outlined above, but replace the cr-sitebin command with ru-site.

447Customizing Your ProductExample Four-Post Analysis

Test Description

You can use the four-post test rig to investigate the vertical dynamics of the full vehicle and its suspension systems. You can then plot the time-based results and study them in the frequency domain to understand the various ride modes and their respective damping levels. The investigation will also help you learn more about the influences of the vehicle's vertical dynamics effects on handling behavior by studying the system's dynamic responses, which includes:

• Front-to-rear modal balance

• Suspension-to-body transfer function gain and phase

• Suspension-to-tire transfer function gain and phase

• Tire contact patch vertical load variation

The test involves assembling a standard full-vehicle model to a four-post test rig. The test rig is defined by four parts representing the tire pads that support the vehicle. The tire pads are constrained to move only in the vertical direction and a displacement actuator, or motion controller, controls their vertical motion.

The only constraint between the pads and the vehicle's tires is the friction of the tires.

Not all tire models have adequate zero speed modeling for being used with the four-post rig test: a rolling tire acts as a damper because the force response depends on tire slip speeds; a non-rolling tire should act as a spring and forces must depend on tire deflection.

All Adams/Tire tire models support the four-post rig test when used in transient mode. For most tire models this means that the USE_MODE in the tire property file must be larger then 10. The exceptions are:

• UA-Tire, USE_MODE must be set to 2

• The Basic and Enhanced tire model property files must specify a RELAXATION_LENGTH larger then zero.

• FTire is in transient mode by default.

An analytical function controls the vertical actuators. Analytical functions also describe the displacement profile of the actuator in the time domain and they are limited to constant amplitude sinusoidal input that sweeps over a predetermined frequency range in a set amount of time. When using the analytical function control, users can use four excitation modes:

• Heave - All tire pads move vertically in phase.

• Pitch - The front tire pads move 180o out of phase with the rear tire pads.

• Roll - The left tire pads move 180o out of phase with the right tire pads.

• Warp - The left-front and right-rear tire pads move 180o out of phase with the right-front and left-rear pads.


448

Test Rig Description

We created the test rig __acme_4PostRig in Adams/Car Template Builder. Its major role is analysis and it contains four general parts for each of the pads, and four actuators for each of the vertical translation joints on each pad. The location of all of the pads and their respective constraints, such as actuators, are parameterized in the ground plane (x and y) to a wheel-center location communicator that comes from the suspension systems. The vertical location is parameterized to the z location of the marker std_tire_ref. The marker std_tire_ref has its z height set automatically during the assembly process so that it represents the average tire contact patch height of the vehicle.

Four-Post Test Rig

Loading an Assembly with the Test Rig

Once you have successfully built the site binary file and started the site version of Adams/Car, you must open the assembly that we have also provided in the examples directory (cdb.cdb) mentioned in Extracting the Files.

If you have not already added the database to your .acar.cfg file, you should do the following:

• From the Tools menu, point to Database Management, and then select Add to Session.


Open the assembly contained in the cdb database as follows:

1. From the File menu, point to Open, and then select Assembly.

2. Open the MDI_Vehicle_4PostRig.asy.

You can also create a new assembly by doing the following:

1. From the File menu, point to New, and then select Full-Vehicle Assembly.

2. Select the appropriate subsystem files.

3. Change the vehicle test rig from __MDI_SDI_TESTRIG to __acme_4PostRig.

4. Select OK.

Running a Test

You should have a full-vehicle assembly mounted to the four-post test rig as shown next.

Use the Command Navigator to submit an analysis using the auto-generated dialog box:

1. To open the Command Navigator, from the Tools menu, select Command Navigator.

2. To run a full-vehicle analysis with the four-post test rig, you must select acme -> analysis -> full_vehicle -> four_post -> submit (double-click).


450

Adams/Car displays the following dialog box (without the values, which we added for your convenience):

3. After the analysis is completed, review the results using the animation and post-processing tools.

Creating and Running a MacroThis topic introduces the concepts of creating and running a macro. While many of the code excerpts are contained in this topic, we also included the appropriate files in the examples directory (install_dir\acar\examples\fourpost\analysis\macros).

You can modify the macro in this directory and then rebuild it in to your Adams/Car site binary file. This allows you to make changes and experiment with macro changes.

• User-Input Parameters

• About the Simulation Process

• Creating the Macro

• Adding the Four-Post Analysis Macro to a Binary


• Testing the New Analysis Macro

• Customizing the Four-Post Analysis Dialog Box

User-Input Parameters

Analysis input parameters are the values that you enter to control a simulation or some other event in the template-based products. Analysis input parameters can be grouped into two categories:

• Parameters common to all analyses:

• Output prefix

• End time

• Number of steps

• Type of analysis (interactive, background)

• Analysis log file (yes, no)

• Parameters specific to this four-post test rig. You use the four-post simulation input parameters to define the boundary conditions of the desired vertical excitation test. The parameters are:

• Peak displacement

• Displacement units (such as m, mm, inch)

• Frequency range (units hardcoded to Hz)

• Excitation mode (heave, pitch, roll, or warp)

About the Simulation Process

The following steps outline the simulation process. The simulation process for the vehicle and test rig is similar to any other suspension or full-vehicle simulation.

The simulation process steps are:

1. Perform a check to ensure that the assembly has the correct test rig.

2. Check if an analysis of the same name already exists.

3. Read in the property files.

4. Assign the z location of the marker std_tire_ref based on the average contact patch location of all of the tires to the four wheel pads.

5. Modify the analytical functions of the actuator (jms_left_front_actuator, jms_right_front_actuator, and so on), according to the user-input data:

Based on the analytical drive signal, you must assign the following functions to each actuator:

Left Front - LF_phase*Peak_Amplitude*sin(1/2*360D*Freq_Range/End_Time*Time**2)

Right Front - RF_phase*Peak_Amplitude*sin(1/2*360D*Freq_Range/End_Time*Time**2)

Left Rear - LR_phase*Peak_Amplitude*sin(1/2*360D*Freq_Range/End_Time*Time**2)

Right Rear - RR_phase*Peak_Amplitude*sin(1/2*360D*Freq_Range/End_Time*Time**2)


452

where the following values are assigned to the phase variables in the function:

Heave Mode - LF_Phase, RF_Phase, LR_Phase, RR_Phase = 1.0

Pitch Mode - LF_Phase, RF_Phase = 1.0 & LR_Phase, RR_Phase = -1.0

Roll Mode - LF_Phase, LR_Phase = 1.0 & RF_Phase, RR_Phase = -1.0

Warp Mode - LF_Phase, RR_Phase = 1.0 & RF_Phase, LR_Phase = -1.0

The simulation process involves submitting the simulation to Adams/Solver using a process similar to the full-vehicle simulation process. The simulation needs:

• One static equilibrium

• An initial velocity of 0.0

• A dynamic simulation equal to the end time (specified by user)

To avoid aliasing of the input during the simulation, users should set the maximum time step that the integrator is allowed to take (HMAX argument on the integrator) to at least 1/10 of the maximum frequency range. For example, if the frequency range you set is 20 Hz, then the HMAX should be 1/10*1/20 = 1/200 (0.005).

Creating the Macro

This four-post vertical excitation example provides instructions to help you create your own macro based on a given user scenario. The objective of the analysis is described in Test Description.

Creating the macro involves the following:

• Defining Parameters

• Handling Errors

• Reading Property Files

• Setting Up the Assembly and Test Rig

• Submitting the Analysis

• Logging the Analysis Results

• Finishing up the Macro

Defining Parameters

We determined the parameters for the four-post analysis macro from User-Input Parameters (for a description of the parameters whose values are important for the success of the four-post simulation, see the table Parameter Descriptions):

! $assembly:t=model ! $output_prefix:t=string ! $comment:t=string:d="" ! $end_time:t=real:gt=0 ! $number_of_steps:t=integer:gt=0 ! $analysis_mode:t=list(interactive,graphical,background):d=interactive


! $peak_displacement:t=real:gt=0 ! $units:t=list(mm):d=mm ! $frequency_range:t=real:gt=0 ! $excitation_mode:t=list(heave,pitch,roll,warp):d=heave ! $load_results:t=list(yes,no):u=yes ! $log_file:t=list(yes,no):u=yes ! $error_variable:t=variable:d=.ACAR.variables.errorFlag

Parameter Descriptions

Handling Errors

With this macro, users must perform the four-post analysis with the .__acme_4PostRig test rig described in Test Rig Description. The assembly and test rig perform actions based on the elements that exist in the .__acme_4PostRig test rig. Therefore, as part of error checking, the macro checks for the correct test rig. For a description of the setup of the assembly and test rig, see About the Simulation Process.

In addition to verifying that the user is using the correct test rig, the macro also checks if the analysis name is unique for this assembly. Notice that we use indenting and comments to make the macro easier to read; as with all programming languages, this is a good practice to get into.

Parameter name: Description:

assembly String value that specifies an existing model. t=model; t specifies type; examples could include real, integer, and so on.

output_prefix String value that specifies the name of the analysis. This name is used to write the analysis files (.adm, .acf, and so on) to the file system and also when the solver files are read back into Adams/Car.

comment Stores comments in the Adams dataset, d=" "; d specifies default, which is an empty string.

end_time Real value that tells Adams/Solver the end time of the four-post analysis. gt=0; gt specifies greater than.

number_of_steps Integer value that tells Adams/Solver the number of output steps.

analysis_mode String value that specifies the mode of the analysis. The three valid modes are interactive, background, or graphical; the list specifies the valid options.

peak_displacement Indicates the maximum amplitude of the shaker pad vertical displacement.

units Hardcoded to millimeters for tutorial, but you can expand it to include other units.

frequency_range Real value indicating the frequency range of the actuator motion functions.

excitation_mode List value that indicates the direction of the shaker pad motions.

load_results Specifies whether to load the results once Adams/Solver has finished the analysis. The default is yes.

log_file Indicates if Adams/Car should generate an analysis log file.


454

variable set variable_name=$error_variable integer=0

!---- Check to ensure the assembly has the proper test rig ---- if condition=($assembly.original_testrig_name != "__acme_4PostRig")

acar toolkit warning & warning="Analysis cannot be submitted!", &

"The assembly does not have the proper testrig. This analysis only", & "works with assemblies using the '__acme_4PostRig' testrig."

variable set variable_name=$error_variable integer=1 return

end

!---- Check if analysis name already exists ---- if condition=(db_exists("$assembly.$'output_prefix'_fourpost"))

if condition=(alert("question","An analysis called \'$'output_prefix'_fourpost\' & already exists. Overwrite it?","Yes","No","",2) == 2)

variable set variable_name=$error_variable integer=1 return

end end

Reading Property Files

After the macro validates the assembly, it reads in and assigns the property file information, using the following code fragment:

!---- Clear out message window ---- acar toolkit message &

message=" " append=no display=no closeable=yes echo_to_logfile=no

!---- Read property files ----acar toolkit read property_files & assembly=$assembly &

verbose=yes & error_variable=$error_variable

if condition=($error_variable != 0)

return

end

Setting Up the Assembly and Test Rig

In this section of the macro, you modify elements of the test rig and assembly to match the values and information entered by the user.

The code fragments for the four-post setup are shown next, with a description for each section, as needed.

!---- Set up the assembly for the maneuver ---- acar toolkit message &

message="Setting up vehicle assembly for four-post shaker..."


You must assign the tire reference markers to the appropriate test pad on the shaker table. The naming conventions for the communicator variables for the reference markers are considered fixed, in that the macro looks for the communicators known to exist in the four-post test rig. Note that the setup of the tire reference markers only occurs once for a particular assembly. If you use the same assembly for multiple four-post analyses, the initial setup will be valid for each analysis.

For each wheel, the tire reference marker is assigned to a shaker pad. The first step is to find each tire in the full-vehicle assembly. The reassignment occurs through an output communicator in the test rig. The communicator holds the name of the part on the shaker pad where you should attach the tire reference marker.

if condition=(!db_exists("$assembly.fourpostSetup")) !--- Parameterize the 4post pad height to the global road height marker

just previously adjusted ---marker modify &

marker_name=$assembly.testrig.ground.std_tire_ref & location=($assembly.ground.std_tire_ref.location) & relative_to=$assembly.testrig.ground

variable set variable=$_self.frontWheel & object_value=(eval(subsystem_lookup($assembly,"wheel","front")))

variable set variable=$_self.leftFrontWheel & object_value=(eval(db_filter_name(db_children($_self.frontWheel[1],"ac_ti

re"),"til_*")))variable set variable=$_self.rightFrontWheel &

object_value=(eval(db_filter_name(db_children($_self.frontWheel[1],"ac_tire"),"tir_*")))variable set variable=$_self.rearWheel &

object_value=(eval(subsystem_lookup($assembly,"wheel","rear")))variable set variable=$_self.leftRearWheel &

object_value=(eval(db_filter_name(db_children($_self.rearWheel[1],"ac_tire"),"til_*")))variable set variable=$_self.rightRearWheel &

object_value=(eval(db_filter_name(db_children($_self.rearWheel[1],"ac_tire"),"tir_*")))marker modify &

marker_name=(eval($_self.leftFrontWheel.object_value.ref_marker.object_value)) & new_marker_name=(eval($assembly.testrig.col_front_pad_mount[1]//"."//$_self.leftFrontWheel.object_value.ref_marker.object_value.name)) marker modify &

marker_name=(eval($_self.rightFrontWheel.object_value.ref_marker.object_value)) &

new_marker_name=(eval($assembly.testrig.cor_front_pad_mount[1]//"."//$_self.rightFrontWheel.object_value.ref_marker.object_value.name))marker modify &

marker_name=(eval($_self.leftRearWheel.object_value.ref_marker.object_value)) &

new_marker_name=(eval($assembly.testrig.col_rear_pad_mount[1]//"."//$_self.leftRearWheel.object_value.ref_marker.object_value.name))marker modify &

marker_name=(eval($_self.rightRearWheel.object_value.ref_marker.object_value)) &

new_marker_name=(eval($assembly.testrig.cor_rear_pad_mount[1]//"."//$_self.rightRearWheel.object_value.ref_marker.object_value.name))

variable set variable=$assembly.fourpostSetup &integer_value=1

end


456

You must reset the motion actuators driving the displacement of the shaker pads for each individual four-post analysis. This is in contrast to the tire reference marker setup, described in the previous paragraphs, which needs to occur only once for a particular assembly, and remains valid for all successive four-post analyses.

Each of the four shaker pads will have the same magnitude of motion, but a specific excitation mode will determine the direction of the motion:

• Heave mode - All four shaker pads move in the same direction.

• Pitch mode - The front and rear tires move in opposite directions.

• Roll mode - The left and right tires move in opposite directions.

• Warp mode - The left front and right rear tires move opposite to the direction traveled by the right front and left rear tires.

You set the different excitation modes by specifying a 1 or -1 multiplier at the beginning of the actuator function definition, as shown next:

!---- Assign actuator functions based on excitation mode ---- !-Heave Excitation if condition=("$excitation_mode" == "heave")

acar template_builder actuator set function & actuator=$assembly.testrig.jms_left_front_actuator & function="1*$peak_displacement*sin(.5*360d*$frequency_range/$end_tim

e*time**2)" acar template_builder actuator set function &

actuator=$assembly.testrig.jms_right_front_actuator & function="1*$peak_displacement*sin(.5*360d*$frequency_range/$end_tim


actuator=$assembly.testrig.jms_left_rear_actuator & function="1*$peak_displacement*sin(.5*360d*$frequency_range/$end_tim


actuator=$assembly.testrig.jms_right_rear_actuator & function="1*$peak_displacement*sin(.5*360d*$frequency_range/$end_tim

e*time**2)" !-- Pitch Excitation elseif condition=("$excitation_mode" == "pitch")


e*time**2)"acar template_builder actuator set function &

actuator=$assembly.testrig.jms_right_front_actuator & function="1*$peak_displacement*sin(.5*360d*$frequency_range/$end_tim


actuator=$assembly.testrig.jms_left_rear_actuator & function="-

1*$peak_displacement*sin(.5*360d*$frequency_range/$end_time*time**2)"acar template_builder actuator set function &

actuator=$assembly.testrig.jms_right_rear_actuator & function="-

1*$peak_displacement*sin(.5*360d*$frequency_range/$end_time*time**2)"


!-- Roll Excitation elseif condition=("$excitation_mode" == "roll")



actuator=$assembly.testrig.jms_right_front_actuator & function="-

1*$peak_displacement*sin(.5*360d*$frequency_range/$end_time*time**2)" acar template_builder actuator set function &

actuator=$assembly.testrig.jms_left_rear_actuator & function="1*$peak_displacement*sin(.5*360d*$frequency_range/$end_tim


actuator=$assembly.testrig.jms_right_rear_actuator & function="-

1*$peak_displacement*sin(.5*360d*$frequency_range/$end_time*time**2)" !-- Warp Excitation elseif condition=("$excitation_mode" == "warp")



actuator=$assembly.testrig.jms_right_front_actuator & function="-


actuator=$assembly.testrig.jms_left_rear_actuator & function="-


actuator=$assembly.testrig.jms_right_rear_actuator & function="1*$peak_displacement*sin(.5*360d*$frequency_range/$end_tim

e*time**2)"end

Submitting the Analysis

After the macro sets up the assembly, you set up the macro to submit the assembly for the four-post analysis. Since this is a full-vehicle assembly, you use the corresponding full-vehicle submission utility macro. Note that the syntax for calling this macro is practically the same as that used in the standard Adams/Car full-vehicle analyses. In this case, two additional parameters are specified to have non-default values for the four-post simulation: generate_road_geometry and simulation_type.

The following shows the code fragment for calling the full-vehicle submission utility macro:

!---- Perform the analysis ---- acar analysis full_vehicle submit &

assembly=$assembly & analysis_name="$'output_prefix'_fourpost" & end_time=$end_time & number_of_steps=$number_of_steps &analysis_mode=$analysis_mode & load_results=$load_results & brief=$brief &


458

road_data_file="BEDPLATE" & generate_road_geometry=no & simulation_type=fourpost

The following table describes the important parameters associated with the four-post full-vehicle submission macro.

Logging the Analysis Results

Once the analysis completed, the macro logs the results to a file. In addition, you can set up the macro so it displays final diagnostic messages to the message window, as follows:

if condition=($log_file) acar analysis full_vehicle log &

assembly=$assembly & analysis_name="$'output_prefix'_fourpost" & analysis_type="Four Post Shaker Test" & analysis_log_file="$'output_prefix'_fourpost.log" & comment=$comment & end_time=$end_time & number_of_steps=$number_of_steps & road_data_file="BEDPLATE" &

initial_velocity=0.0 & velocity_units="m_sec" & input_parameters="general input" & parameter_values=("$number_of_steps")

end

if condition=("$analysis_mode" != "background") acar toolkit message &

message="Simulation is complete." end

Finishing up the Macro

Delete all local variables created in the macro using the $_self nomenclature:

Parameter name: Description:

load_results String value that specifies if the results of the analysis should be read in after the analysis is complete. Expected values are yes or no.

road_data_file Hardcoded to BEDPLATE to indicate that the car will not be driven across a road surface. Adams/Car internally interprets and understands this hardcoded value.

generate_road_geometry Set to no to indicate that Adams/Car should not generate a geometric representation of the data found in the road_data_file.

simulation_type Hardcoded to fourpost to indicate that the full-vehicle will be attached to a four-post shaker table. Adams/Car internally interprets and understands this hardcoded value to produce the correct .adm and .acf files.


variable delete variable_name=(eval(db_children($_self,"variable")))

Adding the Four-Post Analysis Macro to a Binary

You can add the four-post analysis macro to either the private or site binary. The command shown next creates the macro by reading in the command file found at the location you specified. You must place this command either in the acar_build.cmd file as described in Configuring Your Product, or in the macros_ana.cmd file as we have done in the example analysis/macros_ana.cmd, which is read by acar_build.cmd.

macro read macro_name=.acme.macros.mac_ana_ful_fou & file_name=(getenv("MDI_ACAR_SITE")//"/analysis/macros/mac_ana_ful_fou_s

ub.cmd") &user_entered_command="acme analysis full_vehicle four_post submit" & wrap_in_undo=no & create_panel=no

Testing the New Analysis Macro

The easiest way to test the four-post analysis macro is to access it from the Command Navigator. The command you should use is the user_entered_command specified in the acar_build.cmd file shown in Adding the Four-Post Analysis Macro to a Binary.

When you access the four-post macro from the Command Navigator, Adams/Car automatically creates a dialog box based on the parameters in the macro. Users can use this dialog box, shown next, to execute the macro and submit the four-post analysis.


460

Macro-Generated Dialog Box

Customizing the Four-Post Analysis Dialog Box

Now that you created the four-post analysis macro, the custom graphical interface is also almost complete. When you access the four-post macro using the Command Navigator, Adams/Car displays a default dialog box associated with that macro, as shown in figure Macro-Generated Dialog Box. Compare this dialog box to the one shown in figure Customized Dialog Box. The customized dialog box illustrates an example of what you might want to do with the default dialog box generated using the Command Navigator:

• Change the dialog box title.

• Remove the Comments and Error Variable text boxes (they will take on their default values as defined in the macro).

• Modify the Load Results pull-down menu to be radio boxes, and then decrease the area they occupy.

• Shorten the Brief and Log File pull-down menus to match the Load Results radio boxes.

Learn about customizing the interface.


Customized Dialog Box

You can add the four-post custom dialog box to either the private or site binary (or interactively read it in during your Adams/Car session). The command shown next creates the dialog box by reading in the command file found at the location you specify or we have provided an example dialog box in the examples directory (install_dir\acar\examples\fourpost\analysis\dboxes).

We have also provided dboxes_ana.cmd in the example, which contains the following code.

!---- Check if dialog box exists and delete it if it does ---- if condition=(db_exists(".acar.dboxes.dbox_ana_ful_fou_sub"))

interface dialog_box delete dialog_box_name=.acar.dboxes.dbox_ana_ful_fou_subend

!---- Read the Four Post shaker dialog box ---- file command read &file_name=(getenv("MDI_ACAR_SITE")//"/analysis/dboxes/dbox_ana_ful_fou_sub.cmd")

!---- Check if menu button exists and delete it if it does ---- if condition=(db_exists(".gui.main.aca_sta_mbar.simulate.full_vehicle_analysis.ACME_FourPost"))

interface push_button delete &push_button_name =

.gui.main.aca_sta_mbar.simulate.full_vehicle_analysis.ACME_FourPostend


462

!---- Add a menu option ----interface push_button create &

push_button_name = .gui.main.aca_sta_mbar.simulate.full_vehicle_analysis.ACME_FourPost &

enabled = yes &help_text = "Simulate a full-vehicle on the ACME FourPost testrig" &units = relative &horiz_resizing = scale_all &vert_resizing = scale_all &location = 0.0, 0.0 &label = "&ACME Fourpost..." &commands = "interface dialog_box display dialog=.acar.dboxes.dbox_ana_ful_fou_sub"

&default = false

SimManager IntegrationPlease look into Adams/View help for SimManager Integration.

Adams/Car392

Tutorials and ExamplesFor tutorials of overall product use, see:

• Getting Started Using Adams/Car

../getting_started_car/master.htm


466

Example Four-Post AnalysisAlthough this is an Adams/Car example, you can use the general concepts presented here to customize any template-based product.

• Setting Up and Running an Analysis: Teaches the expert user how to build and run a full-vehicle analysis with the four-post test rig.

• Creating and Running a Macro: Introduces the concepts of creating and running a macro for the scenario given above.

467Tutorials and ExamplesExample Event Files

Example Event FilesIn Adams/Car, XML became the default file format for Driving Machine analyses. Although Adams/Car still supports driver control files (.dcf), it now automatically converts them to .xml. The .xml files are referred to as event files. Although the contents of the two files types look different, they contain the same event information. You work with .xml files through the Event Builder.

In the shared Adams/Car database, we provide files in both .dcf and .xml format. These files are stored in the driver_controls.tbl directory/table.

Adams/CarExample .dcd File

468

Example .dcd FileThe following shows the architecture of a .dcd file and all the options you can set for a .dcd file. It contains options, logic, and general rules that you must follow when creating a .dcd file.

[MDI_HEADER]FILE_NAME = filename.dcdFILE_TYPE = 'dcd'FILE_VERSION = 1.0 FILE_FORMAT = 'ASCII'

(COMMENTS){comment_string}'Any comment'

[UNITS]LENGTH = 'meter' || 'millimeter' || 'centimeter' || 'kilometer' || etc.FORCE = 'newton' || 'kilogram_force' || etc. ANGLE = 'deg' MASS = 'kg'TIME = 'sec'

[CLOSED_LOOP]comment = string steering_control = 'none' || 'curvature' || 'path' || 'lat_acc' speed_control = 'none' || 'lon_vel' || 'lon_acc' || 'lat_acc' || 'path'ordinal = 'distance' || 'time'lon_vel_max = float lon_vel_min = float lon_acc_max = float lon_acc_min = float lat_acc_max = float lat_acc_min = float

(DATA) $ steering, speed $ 1 Case{none, none} -- null case, no data required!! $ 2 Case{none, lon_vel}$ 3 Case{none, lon_acc}$ 4 Case{none, lat_acc} -- NOT VALID$ 5 Case{none, path} -- NOT VALID { ( distance || time ) && ( lon_vel || lon_acc ) }

$ 6 Case{curvature, none} -- Must have distance with curvature{ distance && curvature }

$ 7 Case{curvature, lon_vel}$ 8 Case{curvature, lon_acc} $ 9 Case{curvature, lat_acc} $10 Case{curvature, path} -- NOT VALID{ ( distance || time ) && curvature && ( lon_vel || lon_acc || lat_acc ) }

$11 Case{path, none}$12 Case{path, lon_vel}$13 Case{path, lon_acc}$14 Case{path, lat_acc}{ x && y && ( lon_vel || lon_acc || lat_acc ) }

$15 Case{path, path}{ x && y && time }

$16 Case{lat_acc, none} -- NOT VALID

469Tutorials and ExamplesExample .dcd File

$17 Case{lat_acc, lon_vel}$18 Case{lat_acc, lon_acc}$19 Case{lat_acc, lat_acc} -- NOT VALID $20 Case{lat_acc, path} -- NOT VALID { ( distance || time ) && lat_acc && ( lon_vel || lat_acc ) }

[OPEN_LOOP]ordinal = 'time' || 'distance' {distance || time steering throttle brake gear clutch}*

0.0 0.0 0.0 0.0 2 0.0 0.1 0.0 0.0 0.0 2 0.0

*You can select distance or time and any combination of steering, throttle, brake, gear, and clutch

.Example corresponding to $ 2 Case{none,lon_vel}:

.....[CLOSED_LOOP]STEERING_CONTROL = 'NONE'SPEED_CONTROL = 'LON_VEL'ORDINAL = 'TIME'(DATA){ TIME, LON_VEL }0.0 27.7770.1 27.7770.2 27.7760.3 27.7750.4 27.7740.5 27.773 .....

Example corresponding to $ 7 Case{curvature,lon_vel}:.....

[CLOSED_LOOP]STEERING_CONTROL = 'CURVATURE'SPEED_CONTROL = 'LON_VEL'ORDINAL = 'DISTANCE'(DATA){ DISTANCE, CURVATURE, LON_VEL }0.0 0.000 27.777 1.0 0.002 27.777 2.0 0.004 27.777 3.0 0.006 27.776 4.0 0.008 27.775 5.0 0.010 27.774 6.0 0.010 27.773 7.0 0.010 27.7748.0 0.010 27.7749.0 0.010 27.77410.0 0.010 27.77411.0 0.010 27.774 12.0 0.010 27.774 13.0 0.010 27.774 .....

Adams/CarExample Suspension Loadcase File

470

Example Suspension Loadcase FileIn Adams/Car, you can use loadcase files to specify different types of suspension analyses. The following is an example loadcase file.

$-----------------------------------------------MDI_HEADER [MDI_HEADER]FILE_TYPE = 'lcf'FILE_VERSION = 4.0 FILE_FORMAT = 'ASCII'

$-----------------------------------------------UNITS[UNITS]LENGTH = 'mm'ANGLE = 'degrees'FORCE = 'newton'MASS = 'kg'TIME = 'second'$$Generation Parameters: (Do Not Modify!)$ loadcase = 1$ nsteps = 10$ bump_disp = 100.00 rebound_disp = -100.00$ steering_input = angle$ stat_steer_pos = 0.00$

$-----------------------------------------------mode[MODE]STEERING_MODE = 'angle'VERTICAL_MODE = 'length'

$-----------------------------------------------data[DATA]

$COLUMN: input type: type of input data: side:$ (c1) wheel z disp / force left$ (c2) wheel z disp / force right$ (c3) lateral force (y) left$ (c4) lateral force (y) right$ (c5 aligning torque (z-axis) left$ (c6) aligning torque (z-axis) right$ (c7) brake force (y) left $ (c8) brake force (y) right$ (c9) driving force (y) left$ (c10) driving force (y) right$ (c11) steering force / steer angle / rack travel { whl_z_l whl_z_r lat_l lat_r align_l align_r brake_l brake_r drive_l drive_r steer}-100.0000 -100.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000-80.0000 -80.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000-60.0000 -60.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 -40.0000 -40.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000-20.0000 -20.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.00020.0000 20.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.000040.0000 40.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 60.0000 60.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.000080.0000 80.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 100.0000 100.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000

471Tutorials and ExamplesExample Wheel-Envelope Input File

Example Wheel-Envelope Input FileThe following is an example of a wheel-envelope input file (.wen) that you can use to control a wheel-envelope analysis.

$--------------------------------------------MDI_HEADER [MDI_HEADER]FILE_TYPE = 'wen'FILE_VERSION = 5.0 FILE_FORMAT = 'ascii'

$--------------------------------------------UNITS [UNITS]LENGTH = 'mm'FORCE = 'newton'ANGLE = 'deg'MASS = 'kg'TIME = 'sec'

$--------------------------------------------MODE[MODE]STEERING_MODE = 'angle'VERTICAL_MODE = 'length'

$--------------------------------------------GRID [GRID] BOUNDARY_STEERING_GRID = 100.0 BOUNDARY_WHEEL_GRID = 20.0INTERIOR_STEERING_GRID = 100.0 INTERIOR_WHEEL_GRID = 20.0

$--------------------------------------------DATA [DATA]$COLUMN: input type: type of input data: side:$ (c1) wheel z disp / force left$ (c2) wheel z disp / force right$ (c3) lateral force (y) left$ (c4 lateral force (y) right$ (c5) aligning torque (z-axis) left$ (c6) aligning torque (z-axis) right$ (c7) brake force (y) left$ (c8 brake force (y) right$ (c9) driving force (y) left$ (c10) driving force (y) right $ (c11) steering steer angle / rack travel$ {whl_z_l whl_z_r lat_l lat_r align_l align_r brake_l brake_rdrive_l drive_r steer}

-120.0 -120.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 -500.080.0 80.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 -500.090.0 90.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 -300.0120.0 120.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 -200.0120.0 120.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 200.0

Note: For wheel-envelope input files, Adams/Car ignores columns three through ten: (left and right) lateral force, aligining torque, brake force, and driving force.

Adams/CarExample Wheel-Envelope Input File

472

85.0 85.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 350.080.0 80.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 500.060.0 60.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 500.0 30.0 30.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 450.0-30.0 -30.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 450.0-75.0 -75.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 500.0-120.0 -120.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 500.0

473Tutorials and ExamplesExample Wheel-Envelope Output File

Example Wheel-Envelope Output FileA wheel-envelope output file (.wev) contains a header and a data table, as explained next.

The first three lines comprise the header and contain the following information, in this order:

• Type of file

• Adams dataset title

• Date and time of file creation

The table that follows the header contains the following information:

• The first column shows the solution step number

• Columns 2-4 show the data for the left wheel center x, y, z

• Columns 5-7 show the data for the left wheel axis point x, y, z

• Columns 8-10 show the data for the right wheel center x, y, z

• Columns 11-13 show the data for the right wheel axis point x, y, z

The following is an example of a wheel-envelope output file:

Adams/Car Wheel Envelope Analysis Output File - acar_v10.0Adams/Car Assembly2000-01-19 16:41:21

1 -4.2702 -673.57 205.00 -348.83 -1611.7 170.29 7.0293 670.69 205.00 303.63 1620.7 107.88

2 -4.6463 -681.45 225.00 -344.63 -1621.7 206.15 6.7629 678.55 225.00 307.97 1628.3 139.91

3 -4.9532 -687.82 245.00 -340.16 -1630.0 239.60 6.5706 684.92 245.00 311.28 1634.4 170.26

4 -5.2433 -692.82 265.00 -334.67 -1637.0 271.40 6.3755 689.93 265.00 314.35 1639.0 198.89

5 -5.5240 -696.55 285.00 -328.07 -1643.0 301.70 6.1779 693.66 285.00 317.43 1642.1 225.76

6 -5.7905 -699.08 305.00 -320.38 -1648.0 330.44 5.9864 696.18 305.00 320.67 1643.8 250.76

7 -6.0372 -700.45 325.00 -311.59 -1652.1 357.51 5.8099 697.55 325.00 324.25 1644.1 273.76

8 -6.2583 -700.71 345.00 -301.72 -1655.3 382.78 5.6583 697.79 345.00 328.31 1643.0 294.55

9 -6.4469 -699.89 365.00 -290.74 -1657.8 406.03 5.5424 696.93 365.00 333.04 1640.3 312.88

10 -6.5953 -698.01 385.00 -278.64 -1659.4 426.98 5.4752 695.00 385.00 338.63 1636.2 328.39

... .......

Adams/CarExample Plot Configuration File

474

Example Plot Configuration FileThe following is an example of an Adams/Car plot configuration file:

$----------------------------------------------------------------------PAGE [PAGE] PAGE_LAYOUT = 11.0 NUMBER_OF_PLOTS = 1.0 PAGE_NAME = page_1 HEADER_LEFT_LINES = 1.0 HEADER_LEFT_LINE_0_TEXT = 'Header Left' HEADER_LEFT_TEXT_FONT_SIZE = 9.0 HEADER_LEFT_LINES = 1.0 HEADER_LEFT_COLOR = 788529153.0 FOOTER_RIGHT_LINES = 1.0 FOOTER_RIGHT_LINE_0_TEXT = 'Footer Right' HEADER_LEFT_LINES = 1.0 HEADER_LEFT_LINE_0_TEXT = 'Header Left' FOOTER_RIGHT_TEXT_FONT_SIZE = 9.0 FOOTER_RIGHT_COLOR = 788529153.0 $----------------------------------------------------------------------PLOT [PLOT] INDEX = 0.0 NAME = 'plot_1' TIME_LOWER_LIMIT = 0.0 TIME_UPPER_LIMIT = 0.0 AUTO_DATE_STAMP = 1.0 AUTO_ANALYSIS_NAME = 1.0 AUTO_SUBTITLE = 0.0 AUTO_TABLE_HEADER = 1.0 (LEGEND) {placement xloc yloc zloc fill } 2 55.46 85.03 0.00 1 (PLOT_BORDER) {color line_style line_weight} 788529153 1 1.0 (PRIMARY_GRID) {color line_style line_weight} 788529165 1 0.5 (SECONDARY_GRID) {color line_style line_weight} 788529165 1 0.5 (LEGEND_BORDER) {color line_style line_weight} 788529153 1 1.0 (NOTES) NUMBER_OF_NOTES = 3.0 (NOTE_1) {name font color autopos rotation alignment xloc yloc zloc isDate isAnalysis numStrings} 'analysis' 9 788529153 0 0.0 2 54.3200 4.7836 0.0000 0 1 0 1 STRING_1_TEXT = 'Analysis: test1_parallel_travel' (NOTE_2) {name font color autopos rotation alignment xloc yloc zloc isDate isAnalysis numStrings} 'date' 9 788529153 0 0.0 2 117.8513 4.7836 0.0000 1 0 0 1STRING_1_TEXT = '15:52:54 11-MAY-98' (NOTE_3)

475Tutorials and ExamplesExample Plot Configuration File

{name font color autopos rotation alignment xloc yloc zloc isDate isAnalysis numStrings} 'NOTE_3' 10 788529163 1 0.0 4 82.6197 56.0575 0.0000 0 0 0 1STRING_1_TEXT = 'This is my note' (PLOT_AXES) {axis_name type label scaling divisions low_limit up_limit color font rotation alignment placement axis_offset axis_color label_autopos label_offset label_xloc label_yloc tic_color minor_divs auto_divs use_divs incs trailing_zeros dec_places sci_lower sci_upper num_font num_color} 'vaxis' 'vertical' 'No Units' 'linear' 8 0 0 788529153 9 90.0 3 0 0.0 788529153 0 10.9 43.4 49.3 788529153 2 1 1 1.0 0 4 -4 5 9.0 788529153'haxis' 'horizontal' 'Time (sec)' 'linear' 3 0 0 788529153 9 0.0 2 3 0.0 788529153 0 6.5 86.1 4.8 788529153 2 1 1 5.0 0 4 -4 5 9.0 788529153$----------------------------------------------------------------PLOT_CURVE [PLOT_CURVE] NAME = 'curve_1' PLOT = 'plot_1' VERTICAL_AXIS = 'vaxis' HORIZONTAL_AXIS = 'haxis' HORIZONTAL_EXPRESSION = 'toe_angle.TIME' VERTICAL_EXPRESSION = 'toe_angle.right' Y_UNITS = 'no_units' X_UNITS = 'time' LEGEND_TEXT = 'Right' COLOR = 'red' STYLE = 'solid' SYMBOL = 'none' LINE_WEIGHT = 2.0 HOTPOINT = 0.0 INCREMENT_SYMBOL = 1.0

Adams/CarAdams/Car Dynamic Suspension Analysis

476

Adams/Car Dynamic Suspension AnalysisThis example demonstrates the ability to carry out Dynamic Suspension Analysis. Earlier, the Suspension Assembly was limited to carry out only quasi-static simulation. Now, your suspension assembly is simulated with Adams/Solver Simulate/Dynamic command.

This feature allows you to directly provide a RPCIII file or define View Functions to specify Jack and Steering motion as a function of displacement, force etc.

Model Description

Investigate the model and carry out a Dynamic Analysis

Here you first analyze a double wishbone suspension with rigid lower control arm

1. Start Adams/Car, Select Standard Interface.

2. Create a new Suspension assembly: File - New - Suspension Assembly. Fill the dialog box as indicated below. To select the subsystems, Right-click - Search - <acar_shared> to open the file browser.

A Suspension Assembly consisting of a double wishbone suspension and a rack and pinion steering system is provided.

A dynamic suspension analysis is carried out to actuate the wheel pads across a range of frequencies. We are interested in looking at the lower control arm bushing force and how the force changes by replacing the rigid lower control arm by a flexible body. In addition, we use the flex body swap dialog box to switch a rigid lower control arm with a flexible one. We then plot the stress on the flexible body node and visualize it.

477Tutorials and ExamplesAdams/Car Dynamic Suspension Analysis

3. The suspension assembly should be displayed.

4. To simulate using the Dynamic Solver Statements, go to Simulate - Suspension Analysis - Dynamic.

5. You will use View Functions to define the vertical displacement of the Jack. The following function steps up the bounce-rebound amplitude from 10 mm to 30 mm with a frequency of 2 Hz: step(time,2,10*sin(4*pi*time),8,30*sin(4*pi*time))

(Tire Forces can be added using the function like Static Loads Analysis)


478

6. To animate the results, from the Review menu, select Animation Controls. Animate the model and observe the change in the suspension travel.

Review the results

Plot the bushing force in the lca_front bushing:

1. Hit the F8 key in Adams/Car to switch to Adams/PostProcessor.

2. Locate the bkl_lca_front_force and bkr_lca_front_force REQUEST under user-defined REQUESTs:


The fz_front component corresponds to magnitude of the force in the Z direction. Plot this quantity to obtain a figure similar to the following:

Change Rigid Lower Control arm to be a Flexible Body

Here you use the Flex body Swap dialog box feature available in the Standard interface to replace the left rigid lower control arm with a flexible body. The MNF file used for representing this flex body is created in Nastran.

To replace the lower control arm:

1. Go to Adjust - General Part - Rigid to Flex. This displays the flex body swap dialog box.

2. Right click the Current Part Field - Pick and select the Left Lower control arm. In the MNF File field, Right-click - Search - <acar_shared>\flexbodys.tbl and select the LCA_left_tet.mnf file.


480

3. Click on the Connections tab next and highlight the Move column and click Preserve Expression button and click OK.


4. Now, the rigid lower control arm in red is replaced by the white flexible body.

Simulate the Model

You again carry out a dynamic analysis with this model now containing a flexible body.

1. Go to Simulate - Suspension Analysis - Dynamic.

2. Name the Output Prefix to be Rigid_Flex and keep the remaining dialog box unchanged.

After the simulation is successful, animate the model to make sure it is behaving as expected.

Review & Compare Results

Here you plot the bushing force for the lower control arm and compare the force on left and right side.

To review the results:

1. Locate the bkl_lca_front_force and bkr_lca_front_force REQUEST under user-defined REQUESTs:


482

2. Because of the left lower control arm being a flexible body, note the difference in the bushing force.

Optional: Load Durability Plugin to display Stresses and Identify the Hotspots

Here you will load the Durability Plugin and identify the hot-spots on the flexible lower control arm and also plot the nodal stresses. For better visualization, in the Adams/Car Standard Interface change the background color from Black to Gray (Settings - View Background Color).

To Display Stresses and animate the flex body:

1. Change to Adams/Postprocessor and switch to Animation mode.

2. Go to View - Load Animation - select Rigid_Flex_dynamic to load the animation.

3. Go to Tools - Plugin Manager and check the load Adams/Durability option.


4. In the Animation tab right click the Component field and select the flexible body gel_lower_control_arm_flex. This only displays the flexible body and not the whole model.

5. Select the Contour Plots tab; set Contour Plot Type to Von Mises Stress and check Display Legend.

6. Select the Hot Spots tab; check Display HotSpots and fill the dialog box as shown below. You are interested in looking at the top 2 hotspots on the flexible body.

7. Play the animation; you would observe the change in stress with the hot spots being identified.


484

8. From the above exercise, you can note that Node with ID 709 experiences the maximum Von Mises Stress. You can now, plot the stress at this node. Go to Durability menu at the top and select Nodal Plots. The dialog for Nodal Plots pops up. In the Select Node List field, fill in 709, Check Von Mises and click OK.

9. Switch back to Plotting mode in the Adams/PostProcessor, Set the Source to be Result Sets; select gel_lower_control_arm_flex_Stress and component to be node_709_Von_Mises. Your plot should look something like shown below.


Remarks

• The above example, demonstrates a simple use of applying a non standard excitation to a suspension assembly. You could use an RPCIII file from test data to actuate your suspension or use other Adams/View functions. An example RPCIII file (roadprofile_lr_channels.drv) has been provided in the shared car database with your Adams installation (install_dir\acar\shared_car_database.cdb\loadcases.tbl).

• While animating or during plotting of the hot spots/stresses for the first time, you may see a progress bar. This is showing the caching of the Flex Cache Files for improving performance for future animation and post processing.

Adams/CarAdding the vertical setup mode of Adams/Car Suspension Testrig

486

Adding the vertical setup mode of Adams/Car Suspension TestrigThis example demonstrates the enhancement of MDI_SUSPENSION_TESTRIG for quasi-static suspension analysis. The vertical mode named "VERTICAL_MODE_FOR_SETUP" in loadcase file is added to the suspension testrig. "VERTICAL_MODE_FOR_SETUP" means the vertical control method at time=0. Early the user could select only the "VERTICAL_MODE" for the simulation. This feature allows you to set the vertical mode method at the both condition the setup phase(time=0) and the simulation phase.

This new mode is very important for the model including adjustable force. Because when the user correlates with test data, it is important for users how the initial condition is setup in real world and in the simulation.

Model Description

Performing the analysis in order to investigate the vertical setup mode.

Here you first analyze a double wishbone suspension including adjustable force.

1. Start MD Adams 2010, Select Standard Interface.


A Suspension Assembly consisting of a double wishbone suspension including adjustable force and a rack and pinion steering system is provided.

We carry out quasi-static suspension analysis with two setup mode for vertical control. One is "wheel_center_height". Other is "contact_patch_height. And we then plot the toe angle in order to make sure the differences.

487Tutorials and ExamplesAdding the vertical setup mode of Adams/Car Suspension Testrig


4. Go to Adjust - Adjustable Force. And select ".frontsusp_acforce.TR_Front_Suspension_torsional.afl_toe_adjustment" for the "Adjustable Force" field. Then you can see the desired value (-0.5). This value means that the toe angle is adjusted to -0.5 at setup phase.

5. Go to Simulate - Suspension Analysis - Parallel Wheel Travel…

6. Set up the analysis as follows. In this case, the vertical travel of the wheel is controlled to keep 0mm in setup phase.


488

7. Select OK.

8. Go to Simulate - Suspension Analysis - Parallel Wheel Travel… again

9. Set up the analysis as follows for the second analysis. In this case, the vertical travel of the contact patch is controlled to keep 0mm in setup phase.


10. Select OK.

Review the results

Plot the toe angle in two analyses:


2. From the simulation list, select the two analyses.

3. From the right of the dashboard, set Independent Axis to Data. (The Independent Axis Browser appears. You perform the next four steps in the browser.)

4. From the Request list, select wheel travel. You might have to scroll down to see this entry.

5. From the Component list, select vertical_left.

6. Select OK.

Note: "Absolute" at "Control Mode" means that the vertical displacement is controlled the displacement with absolute value. "Relative" means that the displacement is relative to the position at the setup phase.


490

7. Locate the testrig.toe_angle REQUEST under user-defined REQUESTs. And select left in component list.

8. Select Add curve. You can see the plot of wheel_travel vs toe_angle.

The toe angle in Red line(case1...) should be -0.5 by adjustable force when wheel_travel is 0.

9. Create New page.

10. From the right of the dashboard, set Independent Axis to Data. And select jfl_jack_force_data in request list and displacement in component list.

11. Plot the toe angle again. You can see the plot of contact_patch_height vs toe_angle.

The toe angle in Blue line(case2...) should be -0.5 by adjustable force when contact_patch_height is 0.


Remarks

• "VERTICAL_SETUP_MODE" is available with all quasi-static suspension analysis. When you create the loadcase file, the setup mode is described as follows in loadcase file.

[MODE] STEERING_MODE = 'angle' $ wheel_center_height/ contact_patch_height VERTICAL_MODE_FOR_SETUP = 'contact_patch_height' VERTICAL_MODE = 'wheel_center_height' VERTICAL_TYPE = 'absolute' COORDINATE_SYSTEM = 'vehicle'

• "Control Mode" is also described as follows in loadcase file.

[MODE] STEERING_MODE = 'angle' $ wheel_center_height/ contact_patch_height VERTICAL_MODE_FOR_SETUP = 'contact_patch_height' VERTICAL_MODE = 'wheel_center_height' VERTICAL_TYPE = 'absolute' COORDINATE_SYSTEM = 'vehicle'

Adams/CarAdding the length mode for roll analysis of Adams/Car Suspension Testrig

492

Adding the length mode for roll analysis of Adams/Car Suspension TestrigThis example demonstrates the enhancement of MDI_SUSPENSION_TESTRIG for quasi-static suspension analysis. The length mode is added to roll analysis of the suspension testrig. The length mode means that the user can define the vertical length of the center of the table for roll analysis. Early the user could set only vertical total force. This feature allows you to set the vertical mode the either of Force or Length for roll analysis.

Model Description

Performing the roll analysis in order to investigate the vertical mode.

Here you first analyze a double wishbone suspension including adjustable force.

1. Start MD Adams 2010, Select Standard Interface.


A Suspension Assembly consisting of a double wishbone suspension including adjustable force and a rack and pinion steering system is provided.

We carry out roll analysis in quasi-static suspension analysis with two setup mode for vertical control. One is "Force". Other is "Length". And we then plot some requests in order to make sure the differences.

493Tutorials and ExamplesAdding the length mode for roll analysis of Adams/Car Suspension Testrig


4. Go to Adjust - Adjustable Force. And select ".frontsusp_acforce.TR_Front_Suspension_torsional.afl_toe_adjustment" for the "Adjustable Force" field. Then you can see the desired value (-0.5). This value means that the toe angle is adjusted to -0.5 at setup phase.

5. Go to Simulate - Suspension Analysis - Roll & Vertical Force…

6. Set up the analysis as follows. In this case, the vertical mode is controlled with Force mode during the simulation.


494

7. Select OK.

8. Go to Simulate - Suspension Analysis - Roll & Vertical Force… again


9. Set up the analysis as follows. In this case, the vertical mode is controlled with Length mode during the simulation.

10. Select OK.

Review the results


2. From the simulation list, select the first analyses named "mode_Force_roll_angle".

3. From the right of the dashboard, set Independent Axis to Time.


496

4. Locate the left_tire_force and right_force REQUEST under user-defined REQUESTs. And select normal in component list.

5. Select Add curve. The sum of two curves is always 6000N.

6. Create New page.

7. From the simulation list, select the first analyses named "mode_Length_roll_angle".

8. Locate the jfl_jack_force_data and jfr_jack_force_data REQUEST under user-defined REQUESTs. And select displacement in component list.


9. Select Add curve. The sum of two curves is constant. This means that the center of the table is constant during simulation.

Remarks

• When you create the loadcase file for roll analysis, the vertical setup mode is described as follows in loadcase file.

[MODE] STEERING_MODE = 'angle' VERTICAL_MODE_FOR_SETUP = 'wheel_center_height' $ roll_angle / roll_angle_disp VERTICAL_MODE = 'roll_angle_disp' COORDINATE_SYSTEM = 'iso'

Adams/CarGeneral Actuation Analysis feature examples

498

General Actuation Analysis feature examples

Extended description:

• Perform actuation analysis on assemblies.

• Create and modify RPC request map files in a much easier fashion.

• Create and modify actuator setting files (actuator input files) to "import/export" actuator settings.

• Modify actuator parameters in an assembly.

Submitting an actuation analysis

For submitting an actuation analysis, do the following,

1. Open a valid assembly for analysis. The example assembly (actuation_example.asy) provided with the installation may be used as an example.

2. Open the 'General Actuation Analysis' dialog from the menu. (Simulate -> General Actuation Analysis -> Submit Analysis). Note that all valid assemblies open in a session can be accessed through the drop down provided.

499Tutorials and ExamplesGeneral Actuation Analysis feature examples

3. Enter the required parameters in the dialog. Note that the input parameters can be categorized into 3 classes (output control, simulation, actuator setup) as shown in the figure above.

Output control parameters: To define the output files generated as part of the analysis.

Simulation parameters: To define the simulation length, mode etc.

Actuator setup: To setup the actuator parameters.

Note that the actuator setup is done through the 'RPC request map file' and the 'Actuation input file'. Sample files have been provided with the installation and may be used as an example.

4. Hit the OK or Apply button of the dialog, when all parameters have been input. Note that the environment variable MSC_FLATTEN_ADM should not be set.

5. The simulation progress will be indicated by verbose messages displayed in the message window.

6. The end of the simulation will be indicated as shown in the snapshot below,


500

7. Once the analysis is finished, open the post processor (F8) and import the RPC file (extension .rsp) generated as part of the simulation output. The RPC would be located in the current working directory of the session. Plot the results. An example plot is shown in the figure below,


Setting actuator parameters

The user is provided with the option of using a wizard of a tabular interface for editing actuator data. These options can be accessed through the Adjust - Actuators - Table/Wizard menus.

The wizard interface is as shown in the figure below,


502

The desired assembly can be selected from the drop down list of valid assemblies open in the session. Upon selection, all actuators in that assembly are populated in the Actuator drop down.

The desired actuator can be selected either through the drop down or using the up-down arrow buttons. Parameter data related to the selected actuator is displayed in the dialog below and can be set by the user. The settings are saved to the assembly, using the OK/button. Facility is provided to switch to the "table view" from the wizard.

The "table view" for setting actuator parameters is shown below,


The table like interface provides the user with an easy way of looking at a list of actuators at once and activating/deactivating an entire selection. As shown in the figure the desired set of actuators is selected first. Using the 'Activate Selection' and 'De-activate Selection' buttons, the selected set can be activated and de-activated at once.

Besides this, the user can choose to edit the list of selected actuators in the wizard view, using the 'Edit Selection in Wizard' button.

The actuator settings can be saved to a file using the Request map editor functionality, described later.

Request map editor

The request map editor allows the user to work with (view or edit) requests that are defined in the database or import a request map file and edit the requests defined there. The request map editor functionality can be accessed from the menu-group Simulate - General Actuation Analysis - Request Map Editor.

In the "database mode", the user can select to display all browse for a set of requests from the assembly to select (Using the All and Browse buttons respectively).


504

In order to edit the request data in the table, the user needs to explicitly switch to the edit mode, using the corresponding check button provided.

The request data is displayed to the user in the tabular form and can be sorted, which makes it easier to locate and edit the desired request(s). The user may choose to apply the changes to the assembly directly, or alternatively, save the data to a request map file.

Opening/Saving an actuation input map file

An actuation input map file contains a series of parameter-value pairs corresponding to one or more actuators in an assembly. The parameters include major and minor roles of the actuator, scale factor, offset, time offset, RPC function etc. Such a file provides an easy way of setting up a large number of actuators at once.

A facility has been provided to the user to view/open an actuation input map file or create one using actuator data from a valid assembly. The open/save functionality can be accessed from the menu-group Simulate - General Actuation Analysis - Actuation Input File.


It's not necessary to have any valid active assemblies open in a session, in order to view an existing actuation input file. Select the desired file and click on the button with a magnifying glass, in order to open the file. Note that the file gets opened in the user set editor as defined by the optional environment variable MDI_ACAR_USE_EDITOR. If the variable is not defined, then the file is opened in the message window.

If a valid assembly is open in the session, then the verify functionality is available, by which the user can compare the actuator data in an assembly, with that in the file. The comparison reports actuators present in the file that are absent in the assembly as well as incorrect roles set for the actuator, if any. A sample comparison message is shown below,

Alternatively, a valid assembly can be opened and the actuator settings can be changed manually for each desired actuator. Using these settings, an actuation input map file can be generated as follows,


506

A facility to export the settings of actuators that belong to the specific type is provided. By default data belonging to all actuators within an assembly is exported. Specify the file name and the database location to save the file and hit the OK/Apply button to create the file.

507Tutorials and ExamplesPath optimization feature example

Path optimization feature example

Extended description:

Path optimization is a tool that builds a path around a closed road course that approximates the optimum or fastest path for a given vehicle. With this tool, we can visualize the input road file overlaid with the centre line for the optimized path.

In ACar, use Simulate->Full Vehicle Analysis->Path Optimization command to launch the tool. The dialog for path optimization in ACar looks like the one as below

The input road file can be visualized when the "Show" button is pressed. The mandatory fields on this dialog are the "Input Road Data File" and the "Output Path File Name". The road specified by input file can be optimized by providing values for mandatory fields and hitting the OK/Apply button. The output file generated contains the optimized road.

After the optimized road file is generated, the centerline for the optimized path is shown overlaid with the input road. The figure below shows input road file overlaid with the red line, which is the centre line for the optimized path.

Adams/CarPath optimization feature example

508

In AChassis, use Utilities->Path Optimization command to launch the tool. The dialog for path optimization in AChassis looks like the one as below

509Tutorials and ExamplesPath optimization feature example

Adams/CarPath optimization feature example

510

507Dialog Box - F1 Help

Dialog Box - F1 Help

Adams/CarAutomatic Mass Adjustment

508

Automatic Mass Adjustment

(Standard Interface) Simulate Full-Vehicle Analysis Adjust

Adams/Car can automatically adjust the mass properties of an assembly to match the mass properties you input. Learn about Assemblies.

To adjust the aggregate mass, you enter the mass, Centroidal Inertias, and the center-of-mass location relative to a marker. Learn about Markers.

You also select a part that Adams/Car modifies to match the desired mass properties.


Tips on Entering Object Names in Text Boxes.

Assembly Select the name of an assembly.

Generally, you use the automatic mass adjustment for vehicle assemblies, but you can use it with any existing assembly.

Relative to Marker Specify a marker that defines the reference location of the new CG of the assembly. This marker is only used for the CG Location, not the inertias.

CG Location Enter three coordinates that define the position of the new center of gravity (CG) of the assembly with respect to the marker you specify in the Relative to Marker text box.

Modify Part Specify a part whose mass and inertia properties Adams/Car will update to achieve the desired total mass and inertia properties. We recommend that you set this text box to chassis or body of the vehicle so Adams/Car can reduce the mass or inertia, if desired.

To avoid nonphysical conditions, Adams/Car makes a series of Error Checks.

Mass Enter the mass.

Ixx, Iyy, Izz Enter real values that define the inertia property of the model. You must express these values as centroidal inertias.

Off-Diagonal Terms Select to display the cross-term inertias (Ixy, Iyz, and Izx).

Clear its selection to display only principal-terms. If cross-terms are not displayed, their values will not be modified.

If you select Off-Diagonal Terms, Adams/Car displays the following options:

Ixy, Iyz, Izx Enter real values that define the cross-term inertias of your assembly.

509Dialog Box - F1 HelpConvert Files in Database

Convert Files in Database

(Experimental)Tools Dialog Box Display ACAR/dboxes/dbox_too_dat_con

This dialog box is experimental functionality and should be used with caution because it has not been tested to meet the required quality metrics. You can use this dialog box to automatically upgrade a database from one version, such as 11.0, to another, such as 12.0.


From Database Name Select the name of the database you want to convert to the latest version.

To Database Name Select the name of the writable database to which you can write the upgraded entities. The default is the default writable database.

Class of Files Select the type of file you want to convert.

Database Info Select to display the Information window, which lists currently available databases. Learn about Working with the Information Window.

Adams/CarCreate/Modify Differential Gear

510

Create/Modify Differential Gear

(Template Builder) Build Gears Differential Gear New/Modify

Creates or modifies a differential gear. Learn about differential Gears.



Differential Gear Name If creating a differential gear, enter a string to define its name.

If modifying a differential gear, enter its database name.

Input Joint Enter the name of the joint that supplies the input motion.

Output Joint Enter the name of the joint for the output motion. The output joint must be symmetrical; you can enter either the left or right joint.

Reduction Ratio Enter a positive real value for the reduction ratio in the following motion equation:

"input motion" = "reduction_ratio" * ("output motion 1" - "output motion 2")/2

Invert output direction from input direction

Select if you want to invert the motion, which allows the reduction ratio to always be defined as a positive real value.

Active Select if the reduction gear will always be active, or will only be active in the kinematic mode.

Select to display a dialog box where you can add multi-line comments to any entity, to describe its purpose and function. Adams/Car displays different comments dialog boxes, depending on the entity type for which you want to record comments:

• If recording comments for modeling entities in Standard Interface, Adams/Car displays the Entity Comments dialog box.

• If recording comments for any other entity type, Adams/Car displays the Modify Comment dialog box.

Learn about Recording Comments.

511Dialog Box - F1 HelpCreate/Modify Reduction Gear

Create/Modify Reduction Gear

(Template Builder) Build Gears Reduction Gear New/Modify Comprehensive Help

Creates or modifies a reduction gear. Learn about reduction Gears.


Reduction Gear Name If creating a reduction gear, enter a string to define its name.

If modifying a reduction gear, enter its database name.

Input Joint Enter the name of the joint that supplies the input motion.

If you input a cylindrical joint in the Input Joint text box, Adams/Car enables the following option:

Input Type of Freedom Because a reduction gear can work with either of the two Degrees of Freedom in a cylindrical joint, you must specify if the rotational or translational motion will be the input for the gear.

Output Joint Enter the name of the joint for the output motion.

If the input joint and output joint you specified are either both left or both right entities, Adams/Car creates a symmetric reduction gear pair. For any other combination of left/right/single joints, Adams/Car creates a single reduction gear.

If you input a cylindrical joint in the Output Joint text box, Adams/Car enables the following option:

Output Type of Freedom Because a reduction gear can work with either of the two degrees of freedom in a cylindrical joint, you must specify if the rotational or translational motion will be the output for the gear.

Reduction Ratio Enter the real value to be used for the reduction ratio in the following motion equation:

"input motion" = "reduction_ratio" * "output motion"

Invert output direction from input direction

Select if you want to invert the motion, which allows the reduction ratio to always be defined as a positive real value.

Adams/CarCreate/Modify Reduction Gear

512

Active Select if the reduction gear will always be active, or will only be active in the kinematic mode.






513Dialog Box - F1 HelpCreate/Modify Suspension Parameter Array

Create/Modify Suspension Parameter Array

(Template Builder) Build Suspension Parameters Set Comprehensive Help

Defines a Steer Axis.



Steer Axis Calculation Select a method of calculating the steer axis:

• Instant axis - Requires one part and one hardpoint. When using this method, it is very important that you select the correct part and hardpoint information. You can use any part and hardpoint, provided that locking the vertical motion of the part at that hardpoint location actually locks the spring travel. Learn about Hardpoints.

• Geometric - Requires two parts and two coordinate references. Adams/Car creates markers that belong to the specified parts at the desired location (the ones defined by the coordinate references). Learn about Markers.

The geometric method is more intuitive, but sometimes is not applicable (for example, in a suspension where the geometrical information that defines the steer axis is not obvious; where it is impossible to identify the position of the steer axis).

Note: Both methods give accurate results, but the instant axis is more general, because it can be used when the steer axis cannot be determined geometrically (for example in a multi-link suspension).

Suspension Type Select a suspension type:

• Dependent - Select dependent for a driven, solid axle suspension, where the suspension reacts the drive-torque input to the differential pinion gear.

• Independent - Select for all other supensions.

Adams/Car uses this information when calculating the squat and percent anti-squat.

If you set Steer Axis Calculation to Instant Axis, Adams/Car displays the following options:

Part Specify the part you want to use in the definition of the steer axis.

Coordinate Reference Specify a Coordinate Reference to define the location where Adams/Car locks the spring travel.

If you set Steer Axis Calculation to Geometric, Adams/Car displays the following options:

I Part Specify the first part to use in the definition of the steer axis*.

Adams/CarCreate/Modify Suspension Parameter Array

514

J Part Specify the second part to use in the definition of the steer axis*.

I Coordinate Reference Specify a coordinate reference to define the location where Adams/Car creates the first marker (belonging to part I) used in the definition of the steer axis*.

J Coordinate Reference Specify a coordinate reference to define the location where Adams/Car creates the second marker (belonging to part J) used in the definition of the steer axis*.


Note: * For geometric, the steer axis is the line connecting the two markers at the location specified in the coordinate reference field.

515Dialog Box - F1 HelpDelete Road Geometry

Delete Road Geometry

(Standard Interface) Simulate Full-Vehicle Analysis Delete Road Geometry

Deletes the graphics associated with the road. This can be useful when you are using 'fit' commands and the default model becomes very small in relation to the road graphic. Deleting road geometry does not affect the results of the full-vehicle Analysis or your ability to animate the results.

Tip: If you right-click in the main window, away from any modeling elements, and select Fit - no ground, Adams/Car resizes the window, allowing you to see the enlarged default model without worrying about the size of the road graphic.


Full-Vehicle Assembly Select the assembly whose road geometry you want to delete. The menu lists all open assemblies.

Adams/CarDependency Control

516

Dependency ControlSupported only in previous releases

Controls the conceptual suspension spring/damper force elements.


Dependency File Specify the property file (see Property Files) that contains the suspension characteristics definition for the suspension.

Tips on Entering File Names in Text Boxes.

Base, Track, and so on Because Adams/Car applies all the dependencies as a series of super-positions, you can turn off individual dependencies.

If the data is not in the suspension characteristic file (.scf) file, Adams/Car automatically turns off the corresponding dependency. Adams/Car will, therefore, consider a data block in the calculation of a given primary dependency if the data block exists and the corresponding dependency switch is set to 1 in the Dependency_Flags array.

517Dialog Box - F1 HelpEvent Builder

Event Builder

(Standard Interface) Simulate Full-Vehicle Analysis Event Builder

You use the Event Builder to create or modify an XML event file (previously referred to as a driver control file, see XML File Format). Using the Event Builder, you create a series of mini-maneuvers that define a file-driven (see File-Driven Analysis), full-vehicle analysis (see Full-Vehicle Analysis: SmartDriver).

You can start Event Builder in new file mode or in modify mode. The first time you start Event Builder from the Adams/Car Standard Interface, it appears in new file mode. If you want to generate a new event file, from the File menu select New. If you want to edit an existing event file, from the File menu, select Open.

Opening Event Builder again automatically loads the XML file that you were last using.

Adams/Car automatically generates event files when you submit any of the standard events, such as step steer. You can use the Event Builder to modify these files or view them to understand their content. However, you can't view existing TiemOrbit form driver control files (.dcf) without first converting them to XML event files. The shared car database includes sample event files.

If you want to convert existing .dcf files to .xml, from the Tools menu, point to Database Management, point to Version Upgrade, and then select TO XML.


Event File Enter a name for the event file. Adams/Car automatically generates a file with extension .xml in the working directory and updates the Event File text box with the file name you entered.

Speed Enter the initial vehicle speed for the maneuver.

Gear Enter the initial gear position for the maneuver.

Current Field Unit Some quantities have associated units: the current unit text box located at the bottom of the dialog box identifies the units when you place the cursor in the appropriate text box. The default units are SI. You can review and modify these units by selecting Units from the Settings menu, at the top of the Event Builder.

Static Set-up tab - Select the desired static setup method to be performed before the dynamic maneuver. This method is used to set up the vehicle in the desired initial conditions of lateral and longitudinal accelerations.

Adams/CarEvent Builder

518

You can specify static task and initial values for steer, brake, throttle, and clutch signals:

• Task (learn more with Structure of Event Files)

• Initial Steer/Brake/Throttle/Clutch

When Linear is set to yes, a linear analysis is performed after each static equilibrium analysis during the pre-phase.

Note that values computed during Skidpad or Straight static setup overwrite initial steer/throttle signals, in case you selected skidpad or straight.

Gear Shifting Parameters tab - Defines the gear-shifting properties and the shape of the upshift and downshift curves for throttle and clutch signals. (see Structure of Event Files)

Gear Shift Duration of the gear shifting event (> 0.0).

Throttle Raise Delta time of the step function for the ascending curve of the throttle signal (> 0.0).

Clutch Raise Delta time of the step function for the ascending curve of the clutch signal (> 0.0).

Throttle Fall Delta time of the step function for the descending curve of the throttle signal (> 0.0).

Clutch Fall Delta time of the step function for the descending curve of the clutch signal (> 0.0).

Clutch Off Throttle On Delay

Delay between clutch off and throttle on (>0.0).

Clutch On Throttle Off Delay

Delay between clutch on and throttle off (>0.0).

RPM Control Enable a feedback PID controller to eliminate jerk and synchronize engine rotational speed.

Controller Parameters tab – Specify Machine Control’s control actions (see Machine Control Basics)

Rax Saturation When set to true and the vehicle velocity is far from the target, the corresponding acceleration reference profile is altered to let the vehicle reach the target faster [true, false].

Yaw Correction Enables the internal yaw rate controller that operates on the steering, to compensate unpredicted yaw rate events (that is, oversteering) [true, false].

Tire Fz Control When set to true, the Machine Control checks if the driving tires are lifted, and in such a case, cuts throttle [true/false].

Kick-down Control Gear shifting method that chooses the gear that would give the maximum vehicle acceleration [true/false].



Feed Forward When set to true, an instantaneous estimation of the longitudinal control action value is calculated, improving the responsiveness of the control system [true/false].

Throttle Control When set to on, it will control the open loop throttle signal to zero during gear shifting [true/false].

Drive Authority Controls the driving aggressiveness of the SmartDriver Static Simulator [%].

Brake Authority Controls the braking aggressiveness of the SmartDriver Static Simulator [%].

Trajectory Planning Parameters tab – Trajectory planning calculates the connecting contour between the current vehicle position (wherever it may be) and some point on the target path, along which the vehicle will be steered to later bring it back on the target path.

Path Distance Compensation

When set to true and if the vehicle is not exactly over the reference profile, the path distance compensation controller acts to correct the vehicle so that it is over the profile [true/false].

Path Comp. Tolerance Value of the path distance under which the path distance compensation controller is activated (>0.0).

Min Preview Distance Minimum value of the preview distance; even if the vehicle is very slow, the preview distance does not become smaller than this value. It must be set at least as long as the vehicle wheel base (>0.0).

PID’s Speed & Path Parameters tab - Defines the Machine Control PID (Proportional, Integral and Derivative) Controller gains for:

• following a longitudinal velocity or longitudinal acceleration profile.

• steering when following a path.

• following a lateral acceleration profile.

Note: Increasing gains generally produces a quicker controller response, but it also increases controller sensitivity to input disturbance with the risk of becoming unstable.

LonVx P Proportional gain used in correction phase of the feed-forward calculation when following a velocity profile (>0.0).

LonVx I Integral gain used in correction phase of the feed-forward calculation when following a velocity profile (>0.0).

LonVx D Derivative gain used in correction phase of the feed forward calculation when following a velocity profile (>0.0).

LonAx P Proportional gain used in the correction phase of the feed-forward calculation when following an acceleration profile (>0.0).

LonAx I Integral gain used in correction phase of the feed-forward calculation when following an acceleration profile (>0.0).

LonAx D Derivative gain used in correction phase of the feed forward calculation when following an acceleration profile (>0.0).



520

LatPth P Proportional gain used in the correction phase of the feed-forward controller calculation for steering when following a path (>0.0).

LatPth I Integral gain used in the correction phase of the feed-forward controller calculation for steering when following a path (>0.0).

LatPth D Derivative gain used in the correction phase of the feed-forward controller calculation for steering when following a path (>0.0).

LatAy P Proportional gain used in the correction phase of the feed-forward controller calculation when following a lateral acceleration profile (>0.0).

LatAy I Integral gain used in the correction phase of the feed-forward controller calculation when following a lateral acceleration profile (>0.0).

LatAy D Derivative gain used in the correction phase of the feed-forward controller calculation when following a lateral acceleration profile (>0.0).

LatAyC P Proportional gain used in the correction phase of the lateral acceleration control (>0.0).

LatAyC I Integral gain used in the correction phase of the lateral acceleration control (>0.0).

PID’s Steering Output Parameters tab - Defines the Machine Control PID (Proportional, Integral and Derivative) Controller gains for steering output for actuator type being set to Force or Torque.

Once the required steering wheel angle to follow a specified path is calculated by Machine Control (by the feedforward controller and feedback PID controller using the PID gains as shown above), the PID Steering output controller calculates the Force or Torque required to obtain such a steering wheel angle.

SteFrc P Proportional gain for calculation of steering force output (>0.0).

SteFrc I Integral gain for calculation of steering force output (>0.0).

SteFrc D Derivative gain for calculation of steering force output (>0.0).

SteTrq P Proportional gain for calculation of steering torque output (>0.0).

SteTrq I Integral gain for calculation of steering torque output (>0.0).

SteTrq D Derivative gain for calculation of steering torque output (>0.0).



You can use two modes for defining various mini-maneuvers:

• Table Editor - To display, select the Arrow tool .

• Property Editor - To display, you can do either of the following:

• Double-click the mini-maneuver name

• Right-click the mini-maneuver name and select Modify with Property Editor

When editing a mini-maneuver in Property Editor mode, you define the five control signals (steering, brake, throttle, clutch, and gear) and the conditions that end or abort the mini-maneuver. (see Creating Event Files)

Select to display the Table Editor.

Note that at the bottom of the Table Editor, you can add a new mini-maneuver by entering a string in the Name text box and then selecting Add.

Active Set a mini-maneuver to active (yes) or inactive (no). Adams/Car only performs active mini-maneuvers.

Abort Time Specify the relative time from the beginning of the mini-maneuver when the Driving Machine stops the mini-maneuver. It executes the next mini-maneuver if defined. Value must be > 0.0.

Step Size Specify the Adams/Solver Output step size.

H-Max Specify Adams/Solver maximum integration step size.

Note: H-max < Step Size

Steering tab - Define the parameters that control the steering signal during the mini-maneuver that you are creating.

Actuator Type Learn about Specifying an Actuator Type.

Note that the actuator types do not necessarily correspond to the actuators defined in your vehicle model. The Event Builder cannot browse your model and populate the Actuator Type option with the actuators actually defined in your model.



522

Control Method When defining a mini-maneuver, you must specify a control method for each control signal. Different options appear depending on the Control Method you selected. The control methods are:

• open - Uses open-loop control where the control signal is a function of time. (see Open Control Method).

For open loop (time based output control signals) you will have to define parameters for the appropriate control type.

Depending on your selection in the open-loop control type area (adjacent to the parameters mentioned above), you have to specify information to define the shape of the steering control signal.

• machine - Uses closed-loop lateral and longitudinal controllers to follow a path and target velocity or longitudinal acceleration profiles.

For machine control, you have to select the type of closed-loop target for the appropriate application area. (see Machine Control Method).

• SmartDriver - Uses a series of race-optimized lateral and longitudinal controllers. (Requires Adams/SmartDriver.)

For SmartDriver control, you have to define course parameters, such as type of task and course file.(see SmartDriver Control Method).

• human - Uses a human driver module developed by IPG.

For human control, you have to define course parameters, such as type of task and course file.

If you set Control Method to open, Adams/Car displays the following option:

Control Type Learn about Specifying a Control Type.

If you set Control Type to constant, data_driven, data_map, or step, Adams/Car displays the following option:

Control Mode Learn about Specifying a Control Mode.

Throttle/Braking/Gear/Clutch tabs - Contain the same information as the Steering tab, except that the information applies to the particular signal.

Conditions tab


../../adams_smartdriver/master.htm


Environment variables for Longitudinal and Lateral Machine Control PID Controller gains.

Following environment variables can be used to overwrite default values for the longitudinal and lateral Machine Control PID Controller gains. The default values are used for PID controller gains when converting .dcf format Event files, which do not contain the PID controller gains, to .xml format Event files. Also, the environment variables are used to overwrite default values in the Event Builder when creating a new Event. Existing .xml Event files that contain the longitudinal and lateral Machine Control PID Controller gains will not be affected by the environment variables.

Environment variables for the longitudinal PID Controller gains:

MSC_SD_GAIN_LONVXP (Default 100.0)MSC_SD_GAIN_LONVXI (Default 50.0)MSC_SD_GAIN_LONVXD (Default 0.0)MSC_SD_GAIN_LONAXP (Default 30.0)MSC_SD_GAIN_LONAXI (Default 200.0)MSC_SD_GAIN_LONAXD (Default 0.0)

Environment variables for the lateral PID Controller gains:

MSC_SD_GAIN_LATPTHP (Default 0.5)MSC_SD_GAIN_LATPTHI (Default 0.1)MSC_SD_GAIN_LATPTHD (Default 0.0)

Specify a number of conditions for each mini-maneuver. Conditions has two modes: Table Editor and Property Editor, as described next.

• Table Editor - Add new end conditions to the mini-maneuver you are creating. To display,

select the Arrow tool .

The Table Editor mode gives you access to the complete set of parameters. Learn more about Specifying Conditions.

Note that the conditions do not necessarily correspond to the condition defined in your vehicle model. This is an extensive list but the Event Builder cannot browse your model and populate the Type option menu with the condition actually defined in your model.

• Property Editor - Define parameters for the condition. To display, you can do either of the following:

• Double-click the mini-maneuver name

• Right-click the mini-maneuver name and select Modify with Property Editor

Current Field Unit Shows the current units of the quantity you are entering. For example, if you specify the vehicle speed, this text box loads the corresponding unit string [velocity (meter/s)].



524

MSC_SD_GAIN_LATAYP (Default 1.0)MSC_SD_GAIN_LATAYI (Default 10.0)MSC_SD_GAIN_LATAYD (Default 0.0)MSC_SD_GAIN_LATAYCP (Default 0.003)MSC_SD_GAIN_LATAYCI (Default 0.001)

Environment variables for the steering output PID Controller gains:

MSC_SD_GAIN_STEFRCP (Default 10.0, Note: Adams 2008r1/MD Adams R3 default 2.0)MSC_SD_GAIN_STEFRCI (Default 20.0, Note: Adams 2008r1/MD Adams R3 default 3.0)MSC_SD_GAIN_STEFRCD (Default 3.0)MSC_SD_GAIN_STETRQP (Default 10.0, Note: Adams 2008r1/MD Adams R3 default 3.0)MSC_SD_GAIN_STETRQI (Default 20.0, Note: Adams 2008r1/MD Adams R3 default 2.5)MSC_SD_GAIN_STETRQD (Default 3.0)

The following parameters are not yet supported in the Event Builder, but you can modify them directly in the .xml file:

This parameter: Does the following: Takes the value:

smoothingTime Allows you to filter the output of the Machine Control at the concatenation of mini-maneuvers, therefore, helping you avoid discontinuities in the output from the Machine Control.

Real value > 0.0

samplePeriod [DcfMachine]

Time interval between two consecutive evaluations of the controller during a closed-loop event.

Real value > 0.0

samplePeriod [DcfSmartDriver]

Time interval between two consecutive evaluations of the controller during an Adams/SmartDriver event.

Real value > 0.0

frontAxleCoupling Adams/SmartDriver uses this performance parameter during the calculation of the speed profile (both vehicle limits and user defined limits). This parameter affects the front axle of the vehicle.

Real value > 0.0 default 0.75

rearAxleCoupling Adams/SmartDriver uses this performance parameter during the calculation of the speed profile (both vehicle limits and user defined limits). This parameter affects the rear axle of the vehicle.

Real value > 0.0 default 0.75


useBrake For staticSetup = Straight or Skidpad, setting useBrake = yes instructs the Driving Machine that it can use the brake to achieve desired longitudinal velocity and acceleration.

[yes,no]

haltOnFailure Select yes if you want to stop the simulation in case the quasi-static setup phase is not successful.

[yes,no]

pathPositioning Defines whether the path must be positioned automatically or whether its location is absolute and must remain unchanged.

[automatic, absolute, default]

Adams/CarExternal Files

526

External Files

(Standard Interface) Simulate Suspension Analysis External Files

Performs an analysis that corresponds to the loadcase or wheel-envelope file(s) specified for the analysis itself. To determine what kind of analysis will be performed, see the header of the file itself.

Learn about External-File Analyses.


Suspension Assembly

Select the Suspension Assembly you want to analyze. The menu lists all suspension assemblies currently open in your session.

Output Prefix Enter a string that specifies the Analysis Output Name. The string can contain only alphanumeric characters and underscores (_). Adams/Car appends the name of the loadcase or wheel-envelope file to form the complete analysis name. For example, if you enter test_45 as the output prefix and select ride_input.lcf as the loadcase file, the analysis name becomes test_45_ride_input.

Mode of Simulation Select interactive, graphical, background, or files only.

See Mode of Simulation: Interactive, Mode of Simulation: Graphical, Mode of Simulation: Background, Mode of Simulation: Files_only.

Loadcase/Wheel Envelope Files

Specify the type of files, loadcase or wheel envelope, you want to use. In the text box that follows, enter one or more loadcase or wheel-envelope file(s) taken from active Databases. The file(s) contains all the force/displacement inputs that will be applied to the suspension assembly. Learn about Setting up Suspension Analyses.


Load Analysis Results

Select if you want Adams/Car to read in the suspension analysis results when the analysis completes.

Create Analysis Log File

Select if you want Adams/Car to write information about the assembled model and analysis to an Analysis Log File.

527Dialog Box - F1 HelpExternal Files





Select to view property file information. By default, your template-based product displays this information in the Information window, but you can choose to display the information in a text editor.

Learn about:

• Working with the Information Window



Adams/CarFull-Vehicle Analysis: 3D Road

528

Full-Vehicle Analysis: 3D Road

(Standard Interface) Simulate Full-Vehicle Analysis Course Events 3D Road

Runs a 3D Road Analysis.



Full-Vehicle Assembly Select the Full-Vehicle Assembly you want to analyze. The menu lists all full-vehicle assemblies currently open in your session.

Output Prefix Enter a string that specifies the Analysis Output Name. The string can contain only alphanumeric characters and underscores (_). Adams/Car appends the suffix _smo to form the complete analysis output name. For example, if you enter test_45 as the output prefix, the analysis name becomes test_45_smo.

End Time Specify the time, in seconds, at which the analysis ends.

Number of Steps Specify the number of Output Steps.

Mode of Simulation Select interactive, background, or files only.

See Mode of Simulation: Interactive, Mode of Simulation: Background, Mode of Simulation: Files_only.

3D Road Data File Select a 3D Road Data File. The extension is the same as that of other road data files, but its content is different: it contains information about the road's three-dimensional profile and it is used by the steering controller. For more information, see Road Models in Adams/Tire.

Initial Velocity Enter the initial speed of the vehicle in the units specified in the pull-down menu to the right of the Initial Velocity text box.

Initial Gear Position Specify the initial transmission gear for the analysis. The powertrain subsystem uses this parameter that generally acts as a gain for the throttle-demand output from the cruise control.

Adams/Car stores the gear ratios in the powertrain subsystem.

Speed Control Select one of the following:

• DCD File - Allows you to control the longitudinal dynamics of the vehicle assembly using a driver data file.

• Longitudinal Acc. - Lets you specifically define a longitudinal acceleration value.

If you select DCD File, Adams/Car displays the following option:

529Dialog Box - F1 HelpFull-Vehicle Analysis: 3D Road

Driver Data File Select a driver data file (.dcd) that defines an open- or closed-loop speed controller. Learn about Working with Driver Control Data Files (.dcd).

If you select Longitudinal Acc., Adams/Car displays the following options:

Longitudinal Accel (G's) Enter a value of longitudinal acceleration, expressed in G's.

Start Time Enter a real value that specifies the time at which the speed controller is to start.

Quasi-Static Straight-Line Setup Select to perform a quasi-static prephase analysis before running the transient analysis on your full-vehicle assemblies.

• For all cornering analyses, selecting this option causes Adams/Car to perform a SKID_PAD quasi-static analysis.

• For all other analyses, selecting this option causes Adams/Car to perform a STRAIGHT (sometimes called ClearVision adjustment) analysis.

If you do not select this option, Adams/Car performs a SETTLE analysis.


Note: You cannot select the Quasi-Static Setup option if:

• You do not have a powertrain subsystem in your vehicle assembly, because it is not possible to set the initial condition for the longitudinal or the lateral dynamics (throttle position).

Create Analysis Log File Select if you want Adams/Car to write information about the assembled model and analysis to an Analysis Log File.






Adams/CarFull-Vehicle Analysis: Acceleration

530

Full-Vehicle Analysis: Acceleration

(Standard Interface) Simulate Full-Vehicle Analysis Straight-Line Behavior Acceleration

Runs an Acceleration Analysis.



Output Prefix Enter a string that specifies the Analysis Output Name. The string can contain only alphanumeric characters and underscores (_). Adams/Car appends the suffix _accel to form the complete analysis name. For example, if you enter test_45 as the output prefix, the analysis name becomes test_45_accel.





Road Data File Enter the name of a file that contains road data information. The tire subsystems use this information to calculate the tire/road interaction forces.You can also use a 3D road in this context. Make sure that the vehicle remains on the road, because 3D roads are not as wide as 2D flat roads.



Start Time Enter a real value that specifies the time at which the acceleration is to start.

Open-Loop/Closed-Loop Throttle

Select a mode for the Longitudinal Acceleration Controller:

• Open loop - Specify a final throttle value and a duration of step value. The throttle will step from its initial value to the final value in the specified duration.

• Closed loop - Specify a longitudinal acceleration. The Driving Machine controls the clutch, throttle, and gear shifting. Learn about Using the Driving Machine.

If you select Open-Loop Throttle, Adams/Car displays the following option:

Final Throttle Enter the final position of the throttle as a percentage of total throttle displacement.

531Dialog Box - F1 HelpFull-Vehicle Analysis: Acceleration

Duration of Step Enter the time it takes to step from the initial throttle value to the final throttle value.

If you select Closed-Loop Throttle, Adams/Car displays the following option:

Longitudinal Accel (G's) Enter the longitudinal acceleration, in G's, that will be maintained during the analysis.

Gear Position Specify the initial transmission gear for the analysis. The powertrain subsystem uses this parameter, which generally acts as a gain, for the throttle-demand output from the cruise control. Gear shifting can be turned on.

Steering Input Select one of the following:

• straight line - The controller tries to maintain a straight line.

• free - Allows the steering wheel to rotate in response to forces transmitted to the steering subsystem from the tires and the suspension.

• locked - Locks the steering wheel at the design position.


Adams/CarFull-Vehicle Analysis: Acceleration

532

Shift Gears Select if you want to enable gear shifting. This tells the Driving Machine whether or not the vehicle stays in the specified gear or shifts when engine limits are reached.

Quasi-Static Straight-Line Setup

Select to perform a quasi-static prephase analysis before running the transient analysis on your full-vehicle assemblies.













533Dialog Box - F1 HelpFull-Vehicle Analysis: Braking

Full-Vehicle Analysis: Braking

(Standard Interface) Simulate Full-Vehicle Analysis Straight-Line Behavior Braking

Runs a Braking Analysis.



Output Prefix Enter a string that specifies the Analysis Output Name. The string can contain only alphanumeric characters and underscores (_). Adams/Car appends the suffix _brake to form the complete analysis name. For example, if you enter test_45 as the output prefix, the analysis name becomes test_45_brake.





Road Data File Enter the name of a file that contains road data information. The tire subsystems use this information to calculate the tire/road interaction forces.


You can also use a 3D road in this context. Make sure that the vehicle remains on the road, because 3D roads are not as wide as 2D flat roads.


Start Time Enter a real value that specifies the time at which the analysis is to start.

Open-Loop/Closed-Loop Brake

Select a mode for the Longitudinal Acceleration Controller:

• Open loop - Specify a final brake value and a duration of step value. The brake will step from its initial value to the final value in the specified duration.

• Closed loop - Specify a longitudinal deceleration.

If you select Open-Loop Brake, Adams/Car displays the following option:

Final Brake Enter the final value of the brake demand. This value will depend on how your brake system is modeled and the default units that have been used.

Adams/CarFull-Vehicle Analysis: Braking

534

Duration of Step Enter the time it takes to step from the initial brake value (usually zero) to the final brake value. This is equivalent to the period of time taken to depress the brake pedal and brake pressure to build up.

If you select Closed-Loop Brake, Adams/Car displays the following option:

Longitudinal Decel (G's) Enter the longitudinal deceleration, in G's, that will be maintained during the analysis.

Gear Position Specify the initial transmission gear for the analysis. The powertrain subsystem uses this parameter, which generally acts as a gain, for the brake-demand output from the cruise control. The parameter is constant throughout the analysis.


• straight line - The controller tries to maintain a straight line.

• free - Allows the steering wheel to rotate in response to forces transmitted to the steering subsystem from the tires and the suspension.

• locked - Locks the steering wheel at the design position.










535Dialog Box - F1 HelpFull-Vehicle Analysis: Braking







Adams/CarFull-Vehicle Analysis: Braking-In-Turn

536

Full-Vehicle Analysis: Braking-In-Turn

(Standard Interface) Simulate Full-Vehicle Analysis Cornering Events Braking-In-Turn

Runs a Braking-In-Turn Analysis.



Output Prefix Enter a string that specifies the Analysis Output Name. The string can contain only alphanumeric characters and underscores (_). Adams/Car appends the suffix _bit to form the complete analysis name. For example, if you enter test_45 as the output prefix, the analysis name becomes test_45_bit.





Output Step Size Specify the size of the Output Steps.

Gear Position Specify the initial gear position for the analysis.

Lateral Acceleration (G's) Enter the target lateral acceleration that will be achieved at the start of the braking event.

Turn Radius Enter the turn radius (in length units) of the skidpad on which the vehicle will perform the analysis.

Length Units Select the length units for the turn radius.

Note: These units are not used for Entry Distance.

Turn Direction Select a right or a left turn.

537Dialog Box - F1 HelpFull-Vehicle Analysis: Braking-In-Turn

Steering Input Select either of the following:

• Lock steering while braking - Instructs the Driving Machine controller to maintain the steering angle from the previous mini maneuver. Use this option to understand the vehicle trajectory during the braking event, if a driver were to lock the steering wheel.

• Maintain radius while braking - Instructs the Driving Machine controller to maintain the desired radius. Use this option to investigate the driver activity required to maintain a path. Values of interest typically include the steering-wheel angle and steering-wheel torque.

Brake Deceleration (G's) Specify the Longitudinal Deceleration.

Maximum Brake Duration Enter the time after which Adams/Car should stop the braking maneuver.

Quasi-Static Skidpad Setup Select to perform a quasi-static prephase analysis before running the transient analysis on your full-vehicle assemblies.







Entry Distance Enter a numerical value that defines the initial straight-line section of the analysis. Use the pull-down menu to select the unit definitions; for example, 20 m.

Settle Time Enter a value that describes the duration of the intermediate mini-maneuver INITIAL_SET. See Creating Mini-Maneuvers.

Learn more about INITIAL_SET at Structure of Event Files.


Adams/CarFull-Vehicle Analysis: Braking-In-Turn

538







539Dialog Box - F1 HelpFull-Vehicle Analysis: Constant-Radius Cornering

Full-Vehicle Analysis: Constant-Radius Cornering

(Standard Interface) Simulate Full-Vehicle Analysis Cornering Events Constant Radius Cornering

Runs a Constant-Radius Cornering Analysis.



Output Prefix Enter a string that specifies the Analysis Output Name. The string can contain only alphanumeric characters and underscores (_). Adams/Car appends the suffix _crc to form the complete analysis name. For example, if you enter test_45 as the output prefix, the analysis name becomes test_45_crc.






Gear Position Specify the initial transmission gear for the analysis. The powertrain subsystem uses this parameter that generally acts as a gain for the throttle-demand output from the cruise control.


Turn Radius Enter the radius of the circular path.

Length Units Select the length units for the turn radius. By default, the length units are the model units.


Control Select one of the following:

• velocity - Control of the vehicle is performed in terms of longitudinal velocity.

• lateral acceleration - Control of the vehicle is performed in terms of lateral acceleration.

If you set Control to velocity, Adams/Car displays the following options:

Adams/CarFull-Vehicle Analysis: Constant-Radius Cornering

540

Duration of Maneuver Enter the time interval during which Adams/Car performs the actual constant-radius cornering analysis. This is the time required to get from the initial to the final velocity.

Initial Velocity Enter a value for the initial longitudinal velocity of the vehicle (held constant during the approach to the skidpad).

Final Velocity Enter a value for the final longitudinal velocity of the vehicle.

Velocity Units Select the units of velocity.

If you set Control to lateral acceleration, Adams/Car displays the following options:

Duration of Maneuver Enter the time interval during which Adams/Car performs the actual constant-radius cornering analysis. This is the time required to get from the initial to the final acceleration.

Initial Acceleration Enter a value for the initial lateral acceleration.

Final Acceleration Enter a value for the final lateral acceleration.

Acceleration Units Select the units of acceleration.

Shift Gears Select it if you want to enable the Driving Machine to change gears during the course of the analysis. A gear change during the analysis introduces transients, which depending on model robustness, can produce undesired effects in the Adams/Car Solver.

Clear its selection to force the same gear to remain active during the entire analysis.


541Dialog Box - F1 HelpFull-Vehicle Analysis: Constant-Radius Cornering








If you clear the selection of Quasi-Static Skidpad Setup, Adams/Car enables the following two options:

Entry Distance Enter a numerical value that defines the initial straight-line section of the analysis. Use the pull-down menu to select the unit definitions; for example, 20 m.

Settle Time Enter a value that describes the duration of the intermediate mini-maneuver INITIAL_SET. See Creating Mini-Maneuvers.

Learn more about INITIAL_SET at Structure of Event Files.







Adams/CarFull-Vehicle Analysis: Cornering Steer Release

542

Full-Vehicle Analysis: Cornering Steer Release

(Standard Interface) Simulate Full-Vehicle Analysis Cornering Events Cornering w/Steer Release

Runs a Cornering with Steer Release Analysis.



Output Prefix Enter a string that specifies the Analysis Output Name. The string can contain only alphanumeric characters and underscores (_). Adams/Car appends the suffix _csr to form the complete analysis name. For example, if you enter test_45 as the output prefix, the analysis name becomes test_45_csr.






Gear Position Select a value for the initial transmission gear for the analysis. The powertrain subsystem uses this parameter, which generally acts as a gain, for the throttle-demand output from the cruise control.



Steady-State Prephase Select one of the following:

• Radius and Velocity - Adams/Car performs the analysis in terms of longitudinal velocity and skidpad radius.

• Velocity and Acceleration - Adams/Car performs the analysis in terms of lateral acceleration and longitudinal velocity.

If you set Steady-State Prephase to Radius and Velocity, Adams/Car enables the following options:

Note: For both of the following two options, you can select the units you want to use. Adams/Car will convert the units you specify to model units; for example, 100 km/hr = 27777.78 mm/s.

Radius Enter a value for the radius of the circular path.

Longitudinal Velocity Enter a value for the vehicle target longitudinal velocity. Adams/Car calculates the target lateral acceleration of the vehicle accordingly.

543Dialog Box - F1 HelpFull-Vehicle Analysis: Cornering Steer Release

If you set Steady-State Prephase to Velocity and Acceleration, Adams/Car enables the following options:

Note: For both of the following two options, you can select the units you want to use. Adams/Car will convert the units you specify to model units; for example, 1 g = 9.81 m/s.

Lateral Acceleration Enter the target lateral acceleration. Adams/Car calculates the skidpad radius accordingly.

Longitudinal Velocity Enter the vehicle's target longitudinal velocity.

Quasi-Static Skidpad Setup








Entry Distance Enter a numerical value that defines the initial straight-line section of the analysis. From the pull-down menu, select the units that define the entry distance units.

Settle Time Enter a period of time during which the vehicle must maintain a steady-state condition. For example, if you selected Acceleration and Velocity, the settle time would be the period of time in which the lateral acceleration must be maintained within a 2% tolerance, before the end condition can be triggered.


Adams/CarFull-Vehicle Analysis: Cornering Steer Release

544







545Dialog Box - F1 HelpFull-Vehicle Analysis: Data Driven

Full-Vehicle Analysis: Data Driven Supported only in previous releases

Runs a Data-Driven Analysis.




Output Prefix Enter a string that specifies the Analysis Output Name. The string can contain only alphanumeric characters and underscores (_). Adams/Car generates the output files following this naming convention: the output files are named output_prefix_external_file_name to form the complete analysis name. For example, if you enter test_45 as the output prefix, and if you submit a sine_steer.dri loadcase file, then the output file name becomes test_45_sine_steer.







Driver Input File(s) Enter one or more driver input file(s) from any Adams/Car Database. The file(s) contains all the inputs that will be applied to the full-vehicle assembly.

Initial Steer Value Enter a real value that fixes the initial steer value at the start of the analysis. Adams/Car maintains this steer value until the analysis starts.

Adams/CarFull-Vehicle Analysis: Data Driven

546







547Dialog Box - F1 HelpFull-Vehicle Analysis: Drift

Full-Vehicle Analysis: Drift

(Standard Interface) Simulate Full-Vehicle Analysis Open-Loop Steering Events Drift

Runs a Drift Analysis.



Output Prefix Enter a string that specifies the Analysis Output Name. The string can contain only alphanumeric characters and underscores (_). Adams/Car appends the suffix _drift to form the complete analysis name. For example, if you enter test_45 as the output prefix, the analysis name becomes test_45_drift.

End Time Specify the time, in seconds, at which the analysis ends. Make sure you specify an end time greater than five seconds. Otherwise, the analysis will finish while still in the steady-state pre-phase.

A drift full-vehicle analysis requires a minimum of 10 seconds end time.







Gear Position Specify the initial transmission gear for the analysis. The powertrain subsystem uses this parameter, which generally acts as a gain, for the throttle-demand.


Throttle Ramp Enter the rate of change in time of the throttle.

Steer Value Specify the steering that will be maintained during the drift analysis.

Adams/CarFull-Vehicle Analysis: Drift

548


• Force - Indicates that the steering inputs are forces applied to the rack of the steering subsystem.

• Torque - Indicates that the steering input is a torque applied to the steering wheel.

• Angle - Indicates that the steering inputs are steering wheel angular displacements.

• Length - Indicates that the steering inputs are rack displacements.















549Dialog Box - F1 HelpFull-Vehicle Analysis: File Driven Events

Full-Vehicle Analysis: File Driven Events

(Standard Interface) Simulate Full-Vehicle Analysis File Driven Events

Runs a File-Driven Analysis.



Output Prefix Enter a string that specifies the Analysis Output Name. The string can contain only alphanumeric characters and underscores (_). Adams/Car generates the output files following this naming convention: the output files are called output_prefix_external_file_name to form the complete analysis name. For example, if you enter test_45 as the output prefix, and if you submit a sine_steer.dri loadcase file, then the output file name becomes test_45_sine_steer.




Tips on Entering File Names in Text Boxes

Adams/CarFull-Vehicle Analysis: File Driven Events

550

Driver Control Files Enter one or more event files from any Adams/Car Database. The file(s) contains all the inputs that will be applied to the full-vehicle assembly.


To learn more about event files see Using the Driving Machine.







Learn about:




551Dialog Box - F1 HelpFull-Vehicle Analysis: Fish Hook

Full-Vehicle Analysis: Fish Hook

(Standard Interface) Simulate Full-Vehicle Analysis Open-Loop Steering Events Fish Hook

Runs a Fish-Hook Analysis.



Output Prefix Enter a string that specifies the Analysis Output Name. The string can contain only alphanumeric characters and underscores (_). Adams/Car appends the suffix _fho to form the complete analysis name. For example, if you enter test_45 as the output prefix, the analysis name becomes test_45_fho.






Gear Position Specify the initial transmission gear for the analysis. The powertrain subsystem uses this parameter that acts as a gain for the throttle-demand output from the cruise control.

First Turn Direction Select either left or right to determine the first turn direction.

First Steer Angle Enter a real value that fixes the initial steer value during the first turn of the fish-hook maneuver.

First Step Duration Enter the duration of the first step function.

Duration of First Turn Enter a value that represents the duration of the first steering-wheel angle before moving to the opposite direction for the second turn.

Second Turn Direction Select either left or right to determine the second turn direction.

Second Steer Angle Enter the steer value, relative to the initial steer, that defines the steer position during the final turn of the fish-hook maneuver.

Second Step Duration Enter the duration of the second step function.

Duration of Second Turn Enter a value that specifies the duration of the actual fish-hook mini-maneuver.

Adams/CarFull-Vehicle Analysis: Fish Hook

552















553Dialog Box - F1 HelpFull-Vehicle Analysis: ISO Lane Change

Full-Vehicle Analysis: ISO Lane Change

(Standard Interface) Simulate Full-Vehicle Analysis Course Events ISO Lane Change

Runs an ISO Lane Change analysis.



Output Prefix Enter a string that specifies the Analysis Output Name. The string can contain only alphanumeric characters and underscores (_). Adams/Car appends the suffix _ilc to form the complete analysis name. For example, if you enter test_45 as the output prefix, the analysis name becomes test_45_ilc.





Initial Velocity Enter the initial velocity of the vehicle.

Adams/CarFull-Vehicle Analysis: ISO Lane Change

554










Create Analysis log file Select if you want Adams/Car to write information about the assembled model and analysis to an Analysis Log File.






555Dialog Box - F1 HelpFull-Vehicle Analysis: Impulse Steer

Full-Vehicle Analysis: Impulse Steer

(Standard Interface) Simulate Full-Vehicle Analysis Open-Loop Steering Events Impulse Steer

Runs an Impulse-Steer Analysis.



Output Prefix Enter a string that specifies the Analysis Output Name. The string can contain only alphanumeric characters and underscores (_). Adams/Car appends the suffix _imp to form the complete analysis name. For example, if you enter test_45 as the output prefix, the analysis name becomes test_45_imp.








Gear Position Specify the initial transmission gear for the analysis. The powertrain subsystem uses this parameter that generally acts as a gain for the throttle-demand output from the cruise control. The gear remains constant for the entire analysis, regardless of the selection for the Cruise Control.


Maximum Steer Value The peak steer value of the Steering Input.

Adams/CarFull-Vehicle Analysis: Impulse Steer

556

Cycle Length Specify the duration of the impulse signal.

Start Time Enter a real value that specifies the time at which the analysis is to start.






Cruise Control Select if you want Adams/Car to try to maintain the specified Initial Velocity throughout the analysis, using the longitudinal controller inside the Driving Machine. Learn about Using the Driving Machine.

To use this controller, your assembly must contain a powertrain subsystem.










557Dialog Box - F1 HelpFull-Vehicle Analysis: Impulse Steer








Adams/CarFull-Vehicle Analysis: Lift-Off Turn-In

558

Full-Vehicle Analysis: Lift-Off Turn-In

(Standard Interface) Simulate Full-Vehicle Analysis Cornering Events Lift-Off Turn-In

Runs a Lift-off Turn-in Analysis.



Output Prefix Enter a string that specifies the Analysis Output Name. The string can contain only alphanumeric characters and underscores (_). Adams/Car appends the suffix _lti to form the complete analysis name. For example, if you enter test_45 as the output prefix, the analysis name becomes test_45_lti.







Lateral Acceleration Specify the target lateral acceleration that will be achieved at the start of the lift-off turn-in analysis.




Steering Delay Enter the time that is elapsed between the achievement of the desired lateral acceleration and the additional steering ramp input.

Steering Ramp Enter the rate at which the steering value will change; for example, 60 deg/s.

Throttle Delay Specify the delay of the throttle signal. The first mini-maneuver end condition is based on lateral acceleration. After the end of the mini-maneuver, throttle lift-off takes place with the specified delay.

Throttle Step Duration Specify the duration of the throttle step signal. The throttle is stepped down to zero in the specified amount of time.

559Dialog Box - F1 HelpFull-Vehicle Analysis: Lift-Off Turn-In

Disengage Clutch during Lift-Off

Select it if you want ADA MS/Car to step the clutch signal to one (disengaged clutch) with the specified parameters of delay and step duration.

Clutch Delay Specify the delay of the clutch signal activation after the end of the steady-state cornering prephase maneuver.

Clutch Step Duration Specify the duration of the clutch step signal. The clutch signal is stepped down from zero to one (clutch disengaged) in the specified amount of time.









Settle Time Enter a period of time during which the vehicle must maintain a steady-state condition. For example, if you selected a lateral acceleration of 0.5 g, the settle time would be the time where this acceleration must be maintained with a 2% tolerance before the end condition can be triggered.


Adams/CarFull-Vehicle Analysis: Lift-Off Turn-In

560







561Dialog Box - F1 HelpFull-Vehicle Analysis: Path Optimization

Full-Vehicle Analysis: Path Optimization

(Standard Interface) Simulate Full-Vehicle Analysis Path Optimization...



Input Road Data File Specify the road data file to be optimized. The file can be any of the .xml, .drd or .rdf format

Output Path File Name Specify the location and name for the optimized file which would be created by path optimization routine. The output file will always be in the .drd format irrespective of the format of input road data file

Vehicle Width [m] Specify vehicle width in meters.

Corner Cutting Coefficient Specify Corner Cutting Coefficient. This value should be between 0 and 1. The default value is 1.

Path Distance Weight Specify Path Distance Weight. This value should be positive and the default value is 0.001.

Path Curvature Weight Specify Path Curvature Weight. This value should be positive and the default value is 1.

Maximum Iterations Specify Maximum number of Iterations. The default value is 500.

Path Calculation Precision Specify Path Calculation Precision. The default value is 0.001.

Track/Path Width [m] Specify Track/Path width in meters. The default value is 10.0 meters.

Path Point Spacing [m] Specify Patch point spacing in meters. The default value is 5 meters.

Adams/CarFull-Vehicle Analysis: Power-Off Cornering

562

Full-Vehicle Analysis: Power-Off Cornering

(Standard Interface) Simulate Full-Vehicle Analysis Cornering Events Power-off Cornering

Runs a Power-off Cornering Analysis.



Output Prefix Enter a string that specifies the Analysis Output Name. The string can contain only alphanumeric characters and underscores (_). Adams/Car appends the suffix _poc to form the complete analysis name. For example, if you enter test_45 as the output prefix, the analysis name becomes test_45_poc.





Output Step Size Specify the size of the Output Steps. Adams/Car calculates the total number of steps as total_end_time/output_step_size.

Gear Position Specify the initial transmission gear for the analysis. The powertrain subsystem uses this parameter that generally acts as a gain for the throttle-demand output from the cruise control.


Lateral Acceleration Enter the lateral acceleration of the vehicle achieved at the end of the cornering pre-phase.

Turn Radius Enter the radius of the circular path.


563Dialog Box - F1 HelpFull-Vehicle Analysis: Power-Off Cornering

Steering Input Select either of the following:

• Lock steering during power-off - Instructs the Driving Machine controller to maintain the steering angle from the previous mini-maneuver. Use this option to understand the vehicle trajectory during the power-off event, if the driver were to lock the steering wheel.

• Maintain radius during power-off - Instructs the Driving Machine controller to maintain the desired radius. Use this option to investigate the driver activity required to maintain a path. Values of interest typically include the steering-wheel angle, steering-wheel torque, yaw rate, and roll angle.


Disengage Clutch during Power-Off

Select it if you want Adams/Car to step the clutch signal to one (disengaged clutch) with the specified parameters of delay and step duration.

Throttle Delay Specify the delay of the throttle signal. The first mini-maneuver is time based and has an end time of 10 seconds. Adams/Car performs an intermediate mini-maneuver to ensure the steady-state condition. After the second steady-state maneuver, a throttle power-off takes place with the specified delay.


Clutch Delay Specify the delay of the clutch-signal activation after the end of the steady-state maneuver.

Clutch Step Duration Specify the duration of the clutch-step signal. The clutch signal is stepped down from zero to one (clutch disengaged) in the specified amount of time.


Adams/CarFull-Vehicle Analysis: Power-Off Cornering

564









Settle Time Enter a period of time during which the vehicle must maintain a steady-state condition. For example, if you selected a lateral acceleration of 0.5 g, the settle time would be the time where this acceleration must be maintained with a 2% tolerance before the end condition can be triggered.







565Dialog Box - F1 HelpFull-Vehicle Analysis: Power-Off Straight Line

Full-Vehicle Analysis: Power-Off Straight Line

(Standard Interface) Simulate Full-Vehicle Analysis Straight-Line Behavior Power-off Straight Line

Runs a Power-off Straight Line Analysis.



Output Prefix Enter a string that specifies the Analysis Output Name. The string can contain only alphanumeric characters and underscores (_). Adams/Car appends the suffix _pos to form the complete analysis name. For example, if you enter test_45 as the output prefix, the analysis name becomes test_45_pos.


Output Step Size Specify the size of the Output Steps. Adams/Car calculates total number of steps as total_end_time/output_step_size.






Start Time Enter the duration of the initial-set pre-phase. The second mini-maneuver starts after the start time has elapsed.

Gear Position Specify the initial transmission gear for the analysis. The powertrain subsystem uses this parameter that generally acts as a gain for the throttle-demand output from the longitudinal controllers.


Straight Line Control Select one of the following:

• Yes - Adams/Car uses a machine-type actuator to control the steering signal and follow a straight line.

• No - Allows you to enter a steering-wheel angle value used in the open-loop steering controller.

If you set Straight Line Control to No, Adams/Car enables the following option:

Adams/CarFull-Vehicle Analysis: Power-Off Straight Line

566

SWA Specify the steering-wheel angle (in degrees) for the open-loop steering controller.

Disengage Clutch during Power-Off

Select it if you want ADA MS/Car to operate the clutch with a specified delay and step duration as soon as the power-off maneuver starts. If you do not select it, Adams/Car doesn't releases the clutch during the power-off mini-maneuver.

Throttle Delay Specify the amount of time between the end of the first mini-maneuver and the actual power-off.


Clutch Delay Specify the amount of time between the end of the first mini-maneuver and the actuation of the clutch signal.

Clutch Step Duration Specify the duration of the clutch step signal. The clutch signal is stepped down from zero to one (clutch disengaged) in the specified amount of time.










567Dialog Box - F1 HelpFull-Vehicle Analysis: Power-Off Straight Line








Adams/CarFull-Vehicle Analysis: Ramp Steer

568

Full-Vehicle Analysis: Ramp Steer

(Standard Interface) Simulate Full-Vehicle Analysis Open-Loop Steering Events Ramp Steer

Runs a Ramp-Steer Analysis.



Output Prefix Enter a string that specifies the Analysis Output Name. The string can contain only alphanumeric characters and underscores (_). Adams/Car appends the suffix _ramp to form the complete analysis name. For example, if you enter test_45 as the output prefix, the analysis name becomes test_45_ramp.








Gear Position Specify the initial transmission gear for the analysis. The powertrain subsystem uses this parameter that generally acts as a gain for the throttle-demand output from the cruise control. The gear remains constant for the entire maneuver, regardless of the selection for the Cruise Control.


Ramp Enter the rate at which the steering value will change. The units for this parameter are consistent with the selected Steering Input. If you selected Angle and the model units are degrees and seconds, the ramp will be expressed in degrees/sec.

Start Time Specify the time at which the ramp steer will begin.

569Dialog Box - F1 HelpFull-Vehicle Analysis: Ramp Steer

















Adams/CarFull-Vehicle Analysis: Ramp Steer

570








571Dialog Box - F1 HelpFull-Vehicle Analysis: SS Event Manual Setup

Full-Vehicle Analysis: SS Event Manual SetupSupported only in previous releases

Runs steady-state maneuvers on a Full-Vehicle Assembly.


Full Vehicle Assembly Select the Full-Vehicle Assembly you want to analyze. The menu lists all full-vehicle assemblies currently open in your session.

Body Part Select the body part. This is usually the chassis rigid body part. Adams/Car creates a primitive joint of type inline and a primitive joint of type perpendicular between this part and ground. Learn About Joint Primitives.

Left Front Wheel Center Select the hardpoint (see Hardpoints) or construction frame (see Construction Frames) that identifies the left front wheel-center position.

Left Front Susp Upright Select the upright part. Adams/Car creates a joint primitive of type perpendicular between this part and the suspension hub.

Left Front Susp Hub Select the suspension hub part. Adams/Car creates a joint primitive of type perpendicular between this part and the suspension upright.

Left Rear Wheel Center Select the hardpoint or construction frame that identifies the left rear wheel-center position.

Left Rear Susp Upright Select the rear suspension upright part. Adams/Car creates a joint primitive of type perpendicular between this part and the suspension hub.

Left Rear Susp Hub Select the rear suspension hub part. Adams/Car creates a joint primitive of type perpendicular between this part and the suspension upright.

Left Front Wheel Select the left front wheel. Adams/Car references this element in the control array associated with the steady-state cornering CONSUB. For information on CONSUB, see Welcome to Adams/Solver Subroutines.

Left Rear Wheel Select the left rear wheel. Adams/Car references this element in the control array associated with the steady-state cornering CONSUB.

Steering Wheel Joint Select the steering wheel revolute joint.

Left Drive Torque Enter the powertrain left drive torque. This entity usually corresponds to the rotational actuator created on the left differential revolute joint and acting between the left differential output part and the powertrain part.

Right Drive Torque Enter the powertrain right drive torque. This entity usually corresponds to the rotational actuator created on the right differential revolute joint and acting between the right differential output part and the powertrain part.

Left Drive Variable Select the left powertrain data element variable that specifies the drive torque.

Right Drive Variable Select the right powertrain data element variable that specifies the drive torque.

Adams/CarFull-Vehicle Analysis: Setup Parameters

572

Full-Vehicle Analysis: Setup Parameters

(Standard Interface) Simulate Full-Vehicle Analysis Set Full-Vehicle Parameters

The Driving Machine, when operating in closed-loop mode, must know a series of vehicle-specific parameters to correctly scale the output values.


Full-Vehicle Assembly Select the assembly for which you want to set parameters.

Steering Ratio Enter the dimensionless ratio between the steering wheel angle and the road wheel angle. You can obtain this value by running a steering analysis on the front suspension and steering assembly.

Rack Ratio Enter the rack ratio (angle/length) between the steering hand wheel and the rack displacement expressed in SI units. This parameter influences the response of the controller only when driving by force/displacement.

Max Front Brake Torque Enter the maximum torque, expressed in model units, representing the torque generated for the front axle under maximum brake demand, also expressed in model units.

Max Rear Brake Torque Enter the maximum torque, expressed in model units, representing the torque generated for the rear axle under maximum brake demand, also expressed in model units.

Brake Bias (% Front) Enter the front-to-rear dimensionless ratio. Brake bias can be computed as Max Front Brake Torque / (Max Front Brake Torque + Max Rear Brake Torque).

573Dialog Box - F1 HelpFull-Vehicle Analysis: Single Lane Change

Full-Vehicle Analysis: Single Lane Change

(Standard Interface) Simulate Full-Vehicle Analysis Open-Loop Steering Events Single Lane Change

Runs a Single Lane-Change Analysis.



Output Prefix Enter a string that specifies the Analysis Output Name. The string can contain only alphanumeric characters and underscores (_). Adams/Car appends the suffix _sin to form the complete analysis name. For example, if you enter test_45 as the output prefix, the analysis name becomes test_45_sin.










Maximum Steer Value Enter the peak steer value of the steering input. The maximum steer occurs at (start_value+cycle_length)/4; the minimum steer value occurs at (start_value+cycle_length)*3/4.

Start Time Enter a real value that specifies the time at which the maneuver is to start.

Cycle Length Enter the duration of the sinusoidal cycle.

Adams/CarFull-Vehicle Analysis: Single Lane Change

574







575Dialog Box - F1 HelpFull-Vehicle Analysis: Single Lane Change

















Adams/CarFull-Vehicle Analysis: SmartDriver

576

Full-Vehicle Analysis: SmartDriver

(Standard Interface) Simulate Full-Vehicle Analysis Adams/SmartDriver

Runs a SmartDriver analysis. Learn more about Adams/SmartDriver.




Output Prefix Enter a string that specifies the Analysis Output Name. The string can contain only alphanumeric characters and underscores (_). Adams/Car appends the suffix _smo to form the complete analysis output name. For example, if you enter test_45 as the output prefix, the analysis name becomes test_45_smo.





Course Type Select one of the following:

• Driver Course

• 3D Road

If you set Course Type to Driver Course, Adams/Car displays the following options:

Road Data File Select a road data file (*.rdf) used by the tire subsystem.

Course Data File Select a course data file (*.drd) whose centerline defines the path that your vehicle will attempt to follow.

If you set Course Type to 3D Road, Adams/Car displays the following option:

3D Road Data File Select a 3D road data file. The extension is the same as that of other road data files, but its content is different: it contains information about the road's three-dimensional profile and it is used by the steering controller. For more information, see Road Models in Adams/Tire.


../../adams_smartdriver/master.htm

577Dialog Box - F1 HelpFull-Vehicle Analysis: SmartDriver

Initial Gear Position Specify the initial transmission gear for the analysis. The powertrain subsystem uses this parameter that generally acts as a gain for the throttle-demand output from the cruise control.


Smart Driver Task Select one of the following:

• Vehicle Limits - Pre-computes a velocity profile to achieve the maximum performance for the given path. The process consists of three distinct phases:

• Computation of velocity profile during quasi-static analysis

• Dynamic analysis with internal simplified model

• Feasibility verification on the whole path

If the feasibility verification fails, the internal controller is instructed to take into account the limitations, and the process is repeated until the verification is successful on the entire path.

• User Defined - Similar to the Vehicle Limits option, except that the computer maximum performance accelerations are scaled with the percentage indexes for longitudinal (driving and braking) and lateral (right and turn and left hand turn).

If you set Smart Driver Task to User Defined, Adams/Car displays the following options:

Max Driving Acceleration Real value [0,100] – multiplies the maximum driving longitudinal acceleration to obtain the corresponding limit acceleration.

Max Braking Acceleration Real value [0,100] – multiplies the maximum braking longitudinal acceleration to obtain the corresponding limit acceleration.

Max RH Turn Acceleration Real value [0,100] – multiplies the maximum right hand turn lateral acceleration to obtain the corresponding limit acceleration.

Max LH Turn Acceleration Real value [0,100] – multiplies the maximum left hand turn lateral acceleration to obtain the corresponding limit acceleration.


Adams/CarFull-Vehicle Analysis: SmartDriver

578














579Dialog Box - F1 HelpFull-Vehicle Analysis: Static Equilibrium

Full-Vehicle Analysis: Static Equilibrium

(Standard Interface) Simulate Full-Vehicle Analysis Static and Quasi-static Maneuvers Static Equilibrium

Runs a Static Equilibrium analysis.



Output Prefix Enter a string that specifies the Analysis Output Name. The string can contain only alphanumeric characters and underscores (_). Adams/Car appends the suffix _static to form the complete analysis name. For example, if you enter test_45 as the output prefix, the analysis name becomes test_45_static.

Mode of Simulation Select interactive, or files only.

See Mode of Simulation: Interactive, Mode of Simulation: Files_only.

Static Set-Up Select the desired static setup method to be performed. This method is used to set up the vehicle in the desired initial conditions of lateral and longitudinal accelerations. See Structure of Event Files to learn about the following options.

• None

• Normal

• Settle

• Straight

• Skidpad



Gear Position Specify the transmission gear for the analysis. The powertrain subsystem uses this parameter that generally acts as a gain for the throttle-demand output from the cruise control.


Longitudinal Velocity Enter the speed of the vehicle in the units specified in the pull-down menu to the right of the Longitudinal Velocity text box.

Longitudinal Acceleration Enter the longitudinal acceleration.

Adams/CarFull-Vehicle Analysis: Static Equilibrium

580

Lateral Acceleration Enter the lateral acceleration.

Acceleration Units Select the acceleration units from the pull down menu.


Perform Linear Select if you want to perform a linearization after each individual static equilibrium analysis. If this is selected you can either include or not include the damping by selecting the appropriate option.







581Dialog Box - F1 HelpFull-Vehicle Analysis: Step Steer

Full-Vehicle Analysis: Step Steer

(Standard Interface) Simulate Full-Vehicle Analysis Open-Loop Steering Events Step Steer

Runs a Step Steer Analysis.



Output Prefix Enter a string that specifies the Analysis Output Name. The string can contain only alphanumeric characters and underscores (_). Adams/Car appends the suffix _step to form the complete analysis name. For example, if you enter test_45 as the output prefix, the analysis name becomes test_45_step.










Final Steer Value Enter a final steer value for the steering input. Maximum steer occurs at time start_value + duration.

Step Start Time Enter a real value that specifies the time at which the maneuver is to start.

Duration of Step Specify the time duration over which the steering input changes from the initial value to the final value.

Adams/CarFull-Vehicle Analysis: Step Steer

582

















583Dialog Box - F1 HelpFull-Vehicle Analysis: Step Steer







Adams/CarFull-Vehicle Analysis: Swept-Sine Steer

584

Full-Vehicle Analysis: Swept-Sine Steer

(Standard Interface) Simulate Full-Vehicle Analysis Open-Loop Steering Events Swept-Sine Steer

Runs a Swept-Sine Steer Analysis.



Output Prefix Enter a string that specifies the Analysis Output Name. The string can contain only alphanumeric characters and underscores (_). Adams/Car appends the suffix _swept to form the complete analysis name. For example, if you enter test_45 as the output prefix, the analysis name becomes test_45_swept.










Maximum Steer Value Enter maximum allowable steer value of the steering input.

Initial Frequency Enter the initial frequency of the steering input. The frequency can be described as the number of cycles per unit time.

Maximum Frequency Enter the maximum allowable frequency of the steering input.

Frequency Rate Enter the rate of change of the frequency as a function of time.

Start Time Enter a real value that specifies the time at which the maneuver is to start.

585Dialog Box - F1 HelpFull-Vehicle Analysis: Swept-Sine Steer

















Adams/CarFull-Vehicle Analysis: Swept-Sine Steer

586








587Dialog Box - F1 HelpGenerate Loadcase File

Generate Loadcase File

(Standard Interface) Simulate Suspension Analysis Create Loadcase

Generates a loadcase file and stores it in the Default Writable Database. Learn about loadcase files at Setting up Suspension Analyses.

After you fill in the dialog box and select OK, Adams/Car creates a loadcase file with the extension .lcf, and places it in the default writable database. You can then submit a suspension analysis and use the loadcase file you just created.


Select Loadcase Type Select the type of suspension Analysis that the loadcase file will represent:

• Wheel Travel

• Steering

• Static Load

• Roll & Vert. Force

The dialog box changes as you select the different types of analyses.

The following options are common to all types of loadcase files for suspension analyses:

Number of steps Enter the number of steps.

File Name Enter a name for the loadcase file.

Note: Adams/Car writes all the information used to generate a loadcase file in the DATA block of the file itself.

Adams/CarModify Force Elements

588

Modify Force ElementsSupported only in previous releases

Controls the conceptual suspension spring/damper force elements.



Spring Property File Specify the property file that contains the force-deflection relationship for the spring. See Property Files.

Spring Preload Specify the desired preload for the spring.

Damper Property File Specify the property file containing the force-velocity relationship for the damper.

589Dialog Box - F1 HelpModify Gear

Modify Gear

(Standard Interface) Right-click component Modify

Defines a gear. Learn about Gears.s


Gear Name Enter the Database name of a gear whose reduction ratio you want to modify.


Reduction Ratio Enter the real value to be used for the reduction ratio in the following motion equations:

Differential gear

"input motion" = "reduction_ratio" * ("output motion 1" - "output motion 2")/2

Reduction gear

"input motion" = "reduction_ratio" * "output motion"

Symmetric Enabled when you modify component pairs (or brothers):

• yes - Modify properties of both components in a pair.

• no - Only modify properties of the selected component.

When you modify a single component, this option is disabled because a single component is by nature asymmetric.





Adams/CarNew Full-Vehicle Assembly

590

New Full-Vehicle Assembly

(Standard Interface) File New Full-Vehicle Assembly

Creates a new full-vehicle assembly from the specified subsystems. See Assemblies.



Assembly Name Enter a name for the assembly.

Front Susp Subsystem Do one of the following:

• To search/browse for a subsystem from the database,

right-click the text box next to

• To select a subsystem that is open in the current session,

select . The icon changes to and the text box

is replaced by a pull-down menu from which you can select a subsystem.

Rear Susp Subsystem

Steering Subsystem

Front Wheel Subsystem

Rear Wheel Subsystem

Body Subsystem

Powertrain Subsystem If you want to include a powertrain subsystem in your assembly, select the toggle to the left of the text box. Then, do one of the following:


right-click the text box next to .




591Dialog Box - F1 HelpNew Full-Vehicle Assembly

Brake Subsystem If you want to include a brake subsystem in your assembly, select the toggle to the left of the text box. Then, do one of the following:


right-click the text box next to .




Other Subsystems If you want to include additional subsystems in your assembly, such as anti-roll bars or road graphics, select the toggle to the left of the text box.

• - Right-click the text box and then search/browse

for a subsystem from the database.

• - Right-click the text box and then select a subsystem open in the current session.

Vehicle Test Rig From the pull-down menu, select the Test Rig you want to use in your assembly.






Adams/CarNew Suspension Assembly

592

New Suspension Assembly

(Standard Interface) File New Suspension Assembly

Creates a new suspension assembly from the specified subsystems. See Assemblies and Subsystems.



Assembly Name Enter a name for the assembly.

Suspension Subsystem

Do one of the following:

• To search/browse for a subsystem from the database, right-click the text

box next to .

• To select a subsystem that is open in the current session, select .

The icon changes to and the text box is replaced by a pull-down

menu from which you can select a subsystem.

Steering Subsystem If you want to include a steering subsystem in your assembly, select the toggle to the left of the text box. Then, do one of the following:

• To search/browse for a subsystem from the database, right-click the text

box next to .

• To select a subsystem that is open in the current session, select .

The icon changes to and the text box is replaced by a pull-down

menu from which you can select a subsystem.

Other Subsystems If you want to include additional subsystems in your assembly, such as anti-roll bar, select the toggle to the left of the text box.

• - Right-click the text box and then search/browse for a subsystem from the database.

• - Right-click the text box and then select a subsystem open in

the current session.

593Dialog Box - F1 HelpNew Suspension Assembly

Suspension Test Rig From the pull-down menu, select the test rig you want to use in your assembly.






Adams/CarNo Initial Velocity Group

594

No Initial Velocity Group

(Template Builder) Build Parts No Initial Velocity Group

Defines a group of parts which should not have any initial translational velocity automatically set during analysis setup.

The standard behavior for Adams/Car is to set the initial velocity of any part to the vehicle speed in the global X-direction, and 0 (zero) in the global Y- and Z-directions. If a rotating part does not have it's Center of Mass marker on the rotational axis, then the initial velocity of this part will be overwritten by the default behavior. The same happens to pistons, conrods, and so on which not only travel with the vehicle, but also in other global directions, and should have their initial velocity set accordingly.

Including the part, in the No Initial Velocity group avoids this problem.


Template Name Select the Template in which to modify the No Initial Velocity group.

Part names Enter all parts that should be included in the No Initial Velocity group.

595Dialog Box - F1 HelpOpposite Wheel Travel Analysis

Opposite Wheel Travel Analysis

(Standard Interface) Simulate Suspension Analysis Opposite Wheel Travel

Runs an Opposite Wheel-Travel Analysis.


Suspension Assembly Select the Suspension Assembly you want to analyze. The menu lists all suspension assemblies currently open in your session.

Output Prefix Enter a string that specifies the Analysis Output Name. The string can contain only alphanumeric characters and underscores (_). Adams/Car appends the suffix _opposite_travel to form the complete analysis name. For example, if you enter test_45 as the output prefix, the analysis name becomes test_45_opposite_travel.

Number of Steps Enter a value that corresponds to the number of Solution Steps from the lower bounds to the upper bounds of input.

For example, if you specify 10 steps and -100 mm rebound and 100 mm jounce, Adams/Car temporarily creates a loadcase file that contains left vertical wheel displacement inputs of -100, -60, -20, 20, 60, and 100 mm and right vertical wheel displacement inputs of 100, 60, 20, -20, -60, and -100 mm as shown next:



Vertical Setup Mode Specifies the vertical control method at time=0. This feature allows you to set the vertical mode method at the setup phase (time=0) and at the simulation phase. This is important when correlating with the test data to exactly simulate the real world scenario for the initial condition setup.

Bump Travel Enter a real value that fixes the upper limit of wheel-center displacement relative to the input position. A positive value moves the wheel center upward.

Rebound Travel Enter a real value that fixes the lower limit of wheel-center displacement relative to the input position. A positive value moves the wheel center upward.

Adams/CarOpposite Wheel Travel Analysis

596

Travel Relative To Select one of the following:

• Wheel Center - Represents the center of the wheel.

• Contact Patch - Represents the point of contact between the tire and the road.

Control Mode Specifies how the vertical displacement is controlled.

• Absolute - vertical displacement is controlled with absolute displacement value

• Relative - vertical displacement is controlled with displacement relative to the position at setup phase.

Fixed Steer Position (optional)

Enter a real value that fixes either the rack displacement or the steering wheel, depending on the steering input mode you selected:

• If Steering Input = Length, Adams/Car fixes the rack displacement to the value you specified.

• If Steering Input = Angle, Adams/Car fixes the steering wheel to the value you specified.


• Angle - The steering input is an angle applied to the steering wheel.

• Length - The steering input is a length travel applied to the rack.

Coordinate System Select one of the following:

• Vehicle - Independent tables

• Iso - Dependent or tilting tables

The icon shows the difference between the vehicle and iso coordinate systems.


597Dialog Box - F1 HelpOpposite Wheel Travel Analysis







Adams/CarQuasi-Static Constant Radius Cornering

598

Quasi-Static Constant Radius Cornering

(Standard Interface) Simulate Full-Vehicle Analysis Quasi-Static Maneuvers Constant Radius Cornering

Runs a Quasi-Static Constant-Radius Cornering Analysis.



Output Prefix Enter a string that specifies the Analysis Output Name. The string can contain only alphanumeric characters and underscores (_). Adams/Car appends the suffix _ssc to form the complete analysis name. For example, if you enter test_45 as the output prefix, the analysis name becomes test_45_ssc.






Desired Long Acc (G's) Enter the longitudinal acceleration to be maintained throughout the maneuver. Enter the desired longitudinal acceleration in g's, where 1 g is approximately 9.81 mls2. Typical vehicles can accelerate anywhere between 0.2 and 0.5 g's.

If you assign a negative value to Desired Long Acc, Adams/Car enables the following option:

Deceleration Method Select one of the following:

• throttle off - The powertrain torque is applied to slow down the vehicle.

• braking - The tire forces are applied to slow down the vehicle.

599Dialog Box - F1 HelpQuasi-Static Constant Radius Cornering

Final Lateral Accel (G's) The final lateral acceleration to be reached. Reaching this lateral acceleration signals the end of the maneuver. Enter the desired longitudinal acceleration in g's, where 1 g is approximately 9.81 mls2. The test will ramp the lateral acceleration between 0 and the target lateral acceleration.

Typical vehicles can reach a lateral acceleration between 0.4 and 1.0 g.

• Positive value = right hand turn

• Negative value = left hand turn

Turn Radius Enter the turn radius (in the units specified in the pull-down menu to the right of the Turn Radius text box) of the skidpad on which the vehicle will perform the maneuver.

Bank Angle The bank angle in degrees, with the default being zero.

• Positive value = road banks into corner (that is, outside of turn is higher than inside of turn).

• Negative value = road is off-cambered and banks out of corner (that is, inside of turn is higher than outside of turn).







Adams/CarQuasi-Static Constant Velocity Cornering

600

Quasi-Static Constant Velocity Cornering

(Standard Interface) Simulate Full-Vehicle Analysis Quasi-Static Maneuvers Constant Velocity Cornering

Runs a Quasi-Static Constant-Velocity Cornering Analysis.



Output Prefix Enter a string that specifies the Analysis Output Name. The string can contain only alphanumeric characters and underscores (_). Adams/Car appends the suffix _sss to form the complete analysis name. For example, if you enter test_45 as the output prefix, the analysis name becomes test_45_sss.






Desired Long Acc (G's) Enter a longitudinal acceleration. Adams/Car performs the analysis at the specified longitudinal G level. Enter the desired longitudinal acceleration in g's, where 1 g is approximately 9.81 mls2. Typical vehicles can accelerate anywhere between 0.2 and 0.5 g's.

• positive value = acceleration

• negative value = deceleration

Final Lateral Accel (G's) Enter the final lateral acceleration to be reached in Gs. Reaching this lateral acceleration signals the end of the maneuver.

Enter the desired longitudinal acceleration in g's, where 1 g is approximately 9.81 mls2. The test will ramp the lateral acceleration between 0 and the target lateral acceleration.

Typical vehicles can reach a lateral acceleration between 0.4 and 1.0 g.

• positive value = right hand turn

• negative value = left hand turn

601Dialog Box - F1 HelpQuasi-Static Constant Velocity Cornering

Desired Velocity Specify the vehicle longitudinal velocity instead of the turn radius, in the units specified in the pull-down menu to the right of the Desired Velocity text box. The turn radius is computed as follows:

Lat Acc = Long Velocity**2 / Radius

Bank Angle Enter the bank angle in degrees, with the default being zero.

• positive value = road banks into corner (that is, outside of turn is higher than inside of turn).

• negative value = road is off-cambered and banks out of corner (that is, inside of turn is higher than outside of turn).







Note: The maneuver requires a special set-up to work properly.

Adams/CarQuasi-Static Force-Moment Method

602

Quasi-Static Force-Moment Method

(Standard Interface) Simulate Full-Vehicle Analysis Quasi-Static Maneuvers Force-Moment Method

Runs a series of Quasi-Static Force-Moment Analysis.



Output Prefix Enter a string that specifies the Analysis Output Name. The string can contain only alphanumeric characters and underscores (_). Adams/Car appends the suffix _mmm to form the complete analysis name. For example, if you enter test_45 as the output prefix, the analysis name becomes test_45_mmm.






Initial Side Slip Angle Enter the initial value of the vehicle side-slip angle. A typical value is zero.

Final Side Slip Angle Enter the final value of the vehicle side-slip angle.

Number of Side Slip Steps Enter the number of side-slip steps. This value corresponds to the number of Solution Steps from the initial side-slip angle to the final side-slip angle.

For example, if you specify five solution steps, 0 degrees as the initial side-slip angle, and 10 degrees as the final angle, Adams/Car performs six quasi-static analyses, corresponding to the following side slip angles: 0, 2, 4, 6, 8, and 10.

Steering Amplitude Enter the angle amplitude of the steering wheel. The steering-wheel angle will be a sinusoidal signal with the specified amplitude.

Steering Cycle Duration Enter the duration of each side-slip angle analysis. The sinusoidal steering-wheel signal will sweep an entire cycle within the specified duration.

603Dialog Box - F1 HelpQuasi-Static Force-Moment Method

Longitudinal Velocity Specify the vehicle longitudinal velocity in the units specified in the pull-down menu to the right of the Longitudinal Velocity text box.

Bank Angle Enter the bank angle in degrees, with default being zero.

• positive value - Road banks into corner (that is, outside of turn is higher than inside of turn).

• negative value - Road is off-cambered and banks out of corner (that is, inside of turn is higher than outside of turn).







Adams/CarQuasi-Static Straight-Line Acceleration

604

Quasi-Static Straight-Line Acceleration

(Standard Interface) Simulate Full-Vehicle Analysis Quasi-Static Maneuvers Straight-Line Acceleration

Runs a Quasi-Static Straight-Line Acceleration Analysis.



Output Prefix Enter a string that specifies the Analysis Output Name. The string can contain only alphanumeric characters and underscores (_). Adams/Car appends the suffix _ssa to form the complete analysis name. For example, if you enter test_45 as the output prefix, the analysis name becomes test_45_ssa.

Number of Steps Specify the number of Output Steps

Mode of Simulation Select interactive, background or files only.




Longitudinal Accel (G's) Enter the desired longitudinal acceleration in g's, where 1 g is approximately 9.81 mls2. Typical vehicles can accelerate anywhere between 0.2 and 0.5 g's. If you want to use the deceleration method, enter a value that is less than 0, such as -0.2.

If the Longitudinal Accel text box contains a value that is less than 0, Adams/Car enables the following option:

Deceleration Method Select one of the following:

• throttle off - The powertrain torque is applied to slow down the vehicle.

• braking - The tire forces are applied to slow down the vehicle.

Desired Velocity Specify the initial velocity of the vehicle prior to the acceleration test. The velocity should match the units specified in the units pull-down menu. Specifying this velocity is equivalent to a test driver driving at a steady-state velocity prior to commencing the acceleration test.

605Dialog Box - F1 HelpQuasi-Static Straight-Line Acceleration







Adams/CarSet Toe and Camber Values

606

Set Toe and Camber Values

(Standard Interface) Adjust Suspension Parameters Toe/Camber Values

Sets the Toe and Camber angles for a suspension template.


Toe Angles Enter the toe angles for the left and right side of the vehicle.

Camber Angles Enter the camber angles for the left and right side of the vehicle.

607Dialog Box - F1 HelpSet Toe and Camber Values

Set Toe and Camber Values

(Template Builder) Build Suspension Parameters Toe/Camber Values Set

Sets the Toe and Camber angles for a suspension template.

At the design position of a vehicle, a suspension may have nonzero values of toe and/or camber. You must communicate these values to the wheels so they inherit the camber and toe angles from the suspension. Here you set the design-position values of toe and camber, after which Adams/Car automatically creates Parameter Variables and Communicators which you can then access to orient wheels or other entities.


Toe Angles Enter the toe angles for the left and right side of the vehicle.

Camber Angles Enter the camber angles for the left and right side of the vehicle.

Adams/CarSet a Tire’s Road Data File

608

Set a Tire’s Road Data File

(Standard Interface) Simulate Full-Vehicle Analysis Set Road for Individual Tires

Allows you to specify different Road Data Files for individual wheels, to specify different friction parameters or different wheel inputs.


Wheel Select a wheel.


Road Data File Select the road data file you want to use.


Use default road data file Select if you want to use the default road data file that Adams/Car automatically displays in the Road Data File text box above.

609Dialog Box - F1 HelpSingle Wheel-Travel Analysis

Single Wheel-Travel Analysis

(Standard Interface) Simulate Suspension Analysis Single Wheel Travel

Runs a Single Wheel-Travel Analysis.



Output Prefix Enter a string that specifies the Analysis Output Name. The string can contain only alphanumeric characters and underscores (_). Adams/Car appends the suffix _single_travel to form the complete Analysis name. For example, if you enter test_45 as the output prefix, the analysis name becomes test_45_single_travel.







Side Select one of the following:

• Left - The value in the Fixed Wheel Center text box value fixes the right wheel.

• Right - The value in the Fixed Wheel Center text box value fixes the left wheel.

Fixed Wheel Center Enter a real value that fixes the opposite wheel-center vertical displacement. For example, if you choose set Side to Left and enter 50 mm in this text box, Adams/Car fixes the right side wheel-center vertical wheel center as 50 mm above design position, and moves the left wheel from the lower to the upper bound.

Adams/CarSingle Wheel-Travel Analysis

610







Fixed Steer Position Enter a real value that fixes either the rack displacement or the steering wheel, depending on the selected steering input mode:

• Steering Input = Length, Adams/Car fixes the rack displacement to the specified value.

• Steering Input = Angle, Adams/Car fixes the steering wheel to the entered value.









611Dialog Box - F1 HelpSingle Wheel-Travel Analysis







Adams/CarSuspension Analysis: Dynamic

612

Suspension Analysis: Dynamic

(Standard Interface) Simulate Suspension Analyses Dynamic

Runs a Dynamic analysis



Output Prefix Enter a string that specifies the Analysis Output Name. The string can contain only alphanumeric characters and underscores (_). Adams/Car appends the suffix _dynamic to form the complete analysis name. For example, if you enter test_45 as the output prefix, the analysis name becomes test_45_dynamic.

Duration Specify the amount of time over which you want the simulation to run.

Number of Steps Enter an integer value that corresponds to the number of Solution Steps for the duration of your analysis.

For example, if you specify 500 solution steps for duration of 5.0 seconds, your output step size will be 0.01 seconds.

Mode of Simulation Select interactive, graphical, background, or files only .


Vertical Input Select the type of input you want to specify for the vertical jacks, arbitrary functions or RPC3 File.

Left/Right Jack Function Enter the runtime function expression that will define the left/right vertical jack actuator motion or force.

Typically the function expression will be a function of time, for example an impulse, a simple harmonic function or a frequency sweep.

Select to use the Function Builder to define the runtime function expression for the jack input. Follow Function Builder for more information.

Left/right File Name Enter the name of the RPC3 file.

Left/Right Channel Number

Enter an integer value that maps the RPC3 file channels to the desired input quantity.

Zero Offset Select to offset the RPC3 data by subtracting the channels first date value from the array.

Jack Excitation Mode Select displacement, velocity, acceleration or force.

613Dialog Box - F1 HelpSuspension Analysis: Dynamic

Cornering Force Enter values for the left and the right cornering force, applied at the contact patch.

Braking Force Enter values for the left and the right wheel that fix the upper bound and lower bound of the braking force applied between the test rig table and the wheels, at the tire contact patch. Positive braking force acts in the direction of the rear of the vehicle. This is in the negative direction of the ISO/Tydex coordinate system.

Traction Force Enter values for the traction force, applied at the wheel center.

Aligning Torque Enter values for the left and the right wheel that fix the upper bound and the lower bound of the aligning torques applied between ground and tire patches at the contact patches location.

Overturning Torque Enter values for the overturning torque.

Rolling Res. Torque Enter values for the rolling resistance torque.

Damage Force Enter values for the damage force. Adams/Car applies damage forces perpendicularly to the plane containing the wheel part. They are expressed in the ISO-C (TYDEX C) axis system (for more information, see the Adams/Tire online help).

Damage Radius Enter values for the left and right damage radius. The damage radius determines the position of the point of application of the damage forces:

• A damage radius of 0 corresponds to damage forces applied directly at the wheel center (therefore, at the origin of the ISO-C (TYDEX C) axis system).

• A damage radius of 100 mm corresponds to damage forces applied to a point 100 mm in the negative z direction of the ISO-C (TYDEX C) axis system.

Steering Excitation Mode

Select displacement, velocity or acceleration.

Steering Motion Enter the runtime function expression that will define the steering motion.

Typically the function expression will be a function of time, for example an impulse, a simple harmonic function or a frequency sweep.

Select to use the Function Builder to define the runtime function expression for the steering input. Follow Function Builder for more information.



../../adams_tire/master.htm

Adams/CarSuspension Analysis: Dynamic

614






615Dialog Box - F1 HelpSuspension Analysis: Create Dependent Suspension Curves

Suspension Analysis: Create Dependent Suspension Curves

(Standard Interface) Simulate Suspension Analysis Create Suspension Curves Dependent Suspension Curves

Performs a series of parallel, single travel, and static load analyses on a multibody suspension assembly (see Assemblies), to generate a suspension characteristic file (scf).

The resulting scf file defines the left and right data blocks for a dependent suspension.

See Notes About Dependent/Independent Suspension Curves.



Output Prefix Enter a string that specifies the Analysis Output Name. The string can contain only alphanumeric characters and underscores (_). Adams/Car appends the suffix _scur.scf to form the complete scf file name.

Adams/Car names the series of analyses it uses to generate the scf according to their type: pw for parallel travel, and so on.




Note: To successfully generate an scf file, the bump travel must be greater than the rebound travel. Bump and rebound travel values are used in all the different parallel-travel analyses performed at different steer positions (assuming that your assembly includes a steer subsystem).

Symmetric Lat Force Enter values for both the left and right wheel that fix the upper bound and the lower bound of the lateral forces applied to the wheels at the hub. Positive lateral forces act to move the wheels toward the vehicle's right side.

Symmetric Long Force Enter values for both the left and the right wheel that fix the upper bound and lower bound of the longitudinal force applied to the wheels at the hub. Positive longitudinal forces act to move the wheels rearward.

Adams/CarSuspension Analysis: Create Dependent Suspension Curves

616

Symmetric Aligning Torque

Enter values for both the left and the right wheel that fix the upper bound and the lower bound of the aligning torques applied to the wheels at the hub. Positive aligning torques act to steer the wheel to the left.

Symmetric OTM (overturning moment)

Enter values for both the left and

the right wheel that fix the upper bound and the lower bound of the OTM applied to the wheels at the hub.

Symmetric Braking Torque

Enter values for both the left and the right wheel that fix the upper bound and the lower bound of the braking torques applied to the wheels at the hub.

Number of Force Outputs

Enter an integer that determines the number of different static-load analyses that you want to perform.

For example, if you enter 1, Adams/Car performs three static-load analyses for the right side and three for the left, to evaluate the effect that a force/torque applied to the left wheel carrier has on the right wheel carrier and vice versa.

Single Travel Outputs Enter an integer that determines the number of different single wheel-travel analyses that you want to perform.

For example, if you enter 2, Adams/Car performs four single wheel-travel analyses for the left side and four for the right: each of those will be performed at a different wheel-center heights. The total number of single wheel-travel analyses is equal to 2*(Number of Single Travel Output) + 1. This parameter effectively defines the resolution of the anti-roll bar force data blocks.



617Dialog Box - F1 HelpSuspension Analysis: Create Suspension Curves

Suspension Analysis: Create Suspension Curves

(Standard Interface) Simulate Suspension Analysis Create Suspension Curves Independent Suspension Curves

Performs a series of steering, parallel, single travel, and static load analyses on the multibody suspension assembly (see Assemblies), to generate a suspension characteristic file (scf).

See Notes About Dependent/Independent Suspension Curves.



Output Prefix Enter a string that specifies the Analysis Output Name. The string can contain only alphanumeric characters and underscores (_). Adams/Car appends the suffix _scur.scf to form the complete scf file name. The series of analyses that are used to generate the scf are named according to their type: pw for parallel travel, and so on.




Note: To successfully generate an scf file, the bump travel must be greater than the rebound travel. Adams/Car uses bump and rebound travel values in all the different parallel travel analyses performed at different steer positions (assuming that your assembly includes a steer system).

Symmetric Lat. Force Enter values for both the left and right wheel that fix the upper bound and the lower bound of the lateral forces applied to the wheels at the hub. Positive lateral forces act to move the wheels toward the vehicle's right side.

Symmetric Long. Force Enter values for both the left and the right wheel that fix the upper bound and lower bound of the longitudinal force applied to the wheels at the hub. Positive longitudinal forces act to move the wheels rearward.

Adams/CarSuspension Analysis: Create Suspension Curves

618

Symmetric Alig. Torque Enter values for both the left and the right wheel that fix the upper bound and the lower bound of the aligning torques applied to the wheels at the hub. Positive aligning torques act to steer the wheel to the left.

Symmetric OTM Enter values for both the left and the right wheel that fix the upper bound and the lower bound of the OTM applied to the wheels at the hub.

Symmetric Braking Torque Enter values for both the left and the right wheel that fix the upper bound and the lower bound of the braking torques applied to the wheels at the hub.

Symmetric Steer Travel Enter a real value that defines the maximum steer travel. If a steering system is included in your assembly a number of parallel travel analyses are performed at different steer positions starting from the value you have entered in this text box to the corresponding negative value. These parallel travel analyses are used to generate kinematic dependencies. The number of discrete steer positions is determined by the next parameter.

Number of Steer Outputs Enter an integer that determines the number of different parallel-travel analyses that are being performed. For example if you enter 1, Adams/Car perform three parallel travel analyses: one at zero steer position, and two at symmetric steer positions. The total number of analyses is equal to 2*(Number of Steer Outputs) + 1.

Single Travel Outputs Enter an integer that determines the number of different single wheel-travel analyses that are being performed. For example if you enter 2, Adams/Car performs four single wheel-travel analyses for the left side and four for the right: each of those will be performed at a different wheel-center height. The total number of single wheel-travel analyses is equal to 2*(Number of Single Travel Output) + 1.






619Dialog Box - F1 HelpSuspension Analysis: Parallel Travel

Suspension Analysis: Parallel Travel

(Standard Interface) Simulate Suspension Analysis Parallel Wheel Travel

Runs Wheel-Travel Analyses.



Output Prefix Enter a string that specifies the Analysis Output Name. The string can contain only alphanumeric characters and underscores (_). Adams/Car appends the suffix _parallel_travel to form the complete analysis name. For example, if you enter test_45 as the output prefix, the analysis name becomes test_45_parallel_travel.










Adams/CarSuspension Analysis: Parallel Travel

620




Fixed Steer Position (optional)

Enter a real value that fixes either the rack displacement or the steering wheel, depending on the steering input mode you selected:












621Dialog Box - F1 HelpSuspension Analysis: Roll & Vertical Force

Suspension Analysis: Roll & Vertical Force

(Standard Interface) Simulate Suspension Analysis Roll & Vertical Force

Runs a Roll & Vertical Force Analysis.



Output Prefix Enter a string that specifies the Analysis Output Name. The string can contain only alphanumeric characters and underscores (_). Adams/Car appends the suffix _roll_angle to form the complete analysis name. For example, if you enter test_45 as the output prefix, the analysis name becomes test_45_roll_angle.


For example, if you specify five solution steps, -10 degree and 10 degree roll-angle sweep, the loadcase file that Adams/Car automatically generates will contain roll displacement inputs of -10, -6, -2, 2, 6, and 10 degrees.




Roll Angle Upper Enter a real value that fixes the upper limit of roll angle displacement. The orientation of the tables measures the roll angle. A positive value causes the left test-rig wheel to be moved upward and the right test-rig wheel downward.

Roll Angle Lower Enter a real value that fixes the lower limit of roll angle displacement. The orientation of the tables measures the roll angle. A positive value causes the left test-rig wheel to be moved upward and the right test-rig wheel downward.

Vertical Mode • Force - (Total Vertical Force) you can select the total vertical force

• Length - (Fixed vertical length) you can define the vertical length of the center of the table for roll analysis

Adams/CarSuspension Analysis: Roll & Vertical Force

622

Total Vertical Force Enter a real value that specifies the total amount of vertical force available to the left and right actuators. The value represents the sum of the left and right wheel vertical forces measured by the test-rig tires.

Fixed Steer Position (optional) Enter a real value that fixes either the rack displacement or the steering wheel, depending on the steering input mode you selected:












623Dialog Box - F1 HelpSuspension Analysis: Setup Parameters

Suspension Analysis: Setup Parameters

(Standard Interface) Simulate Suspension Analysis Set Suspension Parameters

Calculates suspension characteristics. You must set Suspension Parameters before you can run a suspension analysis. See Running Suspension Analyses.



Tire Model Select one of the following:

• User Defined

• Property File

If you set Tire Model to User Defined, Adams/Car enables the following two options:

Tire Unloaded Radius Enter a value for the unloaded radius.

Tire Stiffness Enter a positive number that defines the tire stiffness at the input position of the suspension assembly.

If you set Tire Model to Property File, Adams/Car enables the following option:

Tire Property File Enter a tire property file.


Wheel Mass Enter a positive real number that defines the mass of the wheel part.

Sprung Mass Enter the mass of the vehicle supported by the suspensions. For most vehicles, the sprung mass is about 90% of the total unloaded vehicle mass.

CG Height Enter a positive number for the vertical distance from the contact patch to the center of gravity (center of mass) of the sprung mass.

Wheelbase Enter a positive number that describes the longitudinal distance between the front and rear wheel centers.

Drive Ratio Select a number that defines the percentage of the total driving force applied to the front wheels:

• For a front suspension, use a setting of 100 to define a pure front-wheel-drive setup and a setting of 0 to define a pure rear-wheel-drive setup.

• For a rear suspension, use a setting of 0 to define a pure front-wheel-drive setup and a value of 100 to define a pure rear-wheel-drive setup.

• For an all-wheel-drive vehicle, the drive ratio might be, for example, 60.

Adams/CarSuspension Analysis: Setup Parameters

624

Brake Ratio Select the percentage of the total braking force applied to the front wheels. The brake ratio is often called brake bias and is constant. The value defines the proportion of braking force between front and rear axles. For a rear suspension with a constant front/rear proportion of 60/40, this value will be set to 60.

If you set Tire Model to Property File, Adams/Car enables the following option:


Learn about:




Note: • Adams/Car uses the parameters cg_height, wheelbase, sprung_mass, and tire stiffness when calculating:

• Percent anti-dive

• Dive

• Percent anti-lift

• Lift

• Percent anti-squat

• Roll center height

• Adams/Car uses the tire stiffness when calculating:

• Suspension rates

• Total roll rate

625Dialog Box - F1 HelpSuspension Analysis: Static Loads

Suspension Analysis: Static Loads

(Standard Interface) Simulate Suspension Analysis Static Load

Runs a Static Load Analysis.



Output Prefix Enter a string that specifies the Analysis Output Name. The string can contain only alphanumeric characters and underscores (_). Adams/Car appends the suffix _static_load to form the complete analysis name. For example, if you enter test_45 as the output prefix, the analysis name becomes test_45_static_load.


Mode of Simulation Select interactive, graphical, background, or files only.



Cornering Force Enter values for the left and the right cornering force, applied at the contact patch.

Braking Force Enter values for the left and the right wheel that fix the upper bound and lower bound of the braking force applied between the test rig table and the wheels, at the tire contact patch. Positive braking force acts in the direction of the rear of the vehicle. This is in the negative direction of the ISO/Tydex coordinate system (see Notes).

Traction Force Enter values for the traction force, applied at the wheel center.

Vertical Input Select one of the options presented next:

This option: Lets you:

Contact Patch Height

Control the height of the contact patch point. The vertical actuators will move the suspension in the range you specify in the Vertical Length text box.

Wheel Center Height

Control the height of the wheel center points. The vertical actuators will move the suspension in the range you specify in the Vertical Length text box.

Adams/CarSuspension Analysis: Static Loads

626

Wheel Vertical Force

Control the absolute vertical force generated by the tire.

The vertical actuators will move the suspension in the range you specify in the Vertical Force text box.

Wheel Delta Vertical Force

Control the relative vertical force generated by the tire. The vertical actuators will move the suspension in the range specified by the vertical force fields. the force is relative to the vertical tire force generated between the wheel and the pads at static equilibrium position. For example a +-100 N with this option selected means that the test rig will apply +-100 N starting from the static equilibrium load.

Actuator Vertical Force

Directly specify the vertical actuator loads.

Vertical Length/Force Enter values for the vertical wheel input.

Overturning Tor. Enter values for the overturning torque.

Roll. Res. Torque Enter values for the rolling resistance torque.

Damage Force Enter values for the damage force. Adams/Car applies damage forces perpendicularly to the plane containing the wheel part. They are expressed in the ISO-C (TYDEX C) axis system (for more information, see the Adams/Tire online help).

Damage Radius Enter values for the left and right damage radius. The damage radius determines the position of the point of application of the damage forces:

• A damage radius of 0 corresponds to damage forces applied directly at the wheel center (therefore, at the origin of the ISO-C (TYDEX C) axis system).

• A damage radius of 100 mm corresponds to damage forces applied to a point 100 mm in the negative z direction of the ISO-C (TYDEX C) axis system.





../../adams_tire/master.htm

627Dialog Box - F1 HelpSuspension Analysis: Static Loads

Steer Upper/Lower Limit Enter values that fix the upper bound and the lower bound of the rack displacement (if Steering Input = Length), or of the steering wheel (if Steering Input = Angle). Positive rack displacement moves the rack towards the vehicle's right side. Positive steering-wheel angles rotate the steering wheel counterclockwise, typically steering the vehicle to the left.











Adams/CarSuspension Analysis: Static Loads

628

Notes: • Positive values for bump and rebound travel move the wheel centers upward from the design position. Negative values move the wheel centers downward.

• Positive steering-wheel angle rotates the steering wheel counter-clockwise as if making a left turn.

• Positive rack displacement moves the rack toward the right side of the vehicle.

• Forces and torques are expressed as follows:

Force: Point of application: Reference frame:

Lateral force (cornering) Contact patch TYDEX H ISO-W

Longitudinal force (braking) Contact patch TYDEX H ISO-W

Longitudinal force (acceleration) Wheel center TYDEX C ISO-C

Overturning moments Contact patch TYDEX H ISO-W

Rolling resistance torque Contact patch TYDEX H ISO-W

Aligning torque Contact patch TYDEX H ISO-W

629Dialog Box - F1 HelpSuspension Analysis: Steering

Suspension Analysis: Steering

(Standard Interface) Simulate Suspension Analysis Steering

Runs a Steering Analysis.



Output Prefix Enter a string that specifies the Analysis Output Name. The string can contain only alphanumeric characters and underscores (_). Adams/Car appends the suffix _steering to form the complete analysis name. For example, if you enter test_45 as the output prefix, the analysis name becomes test_45_steering.





Upper Steering Limit Enter a real value that fixes the upper limit of steer travel. Adams/Car interprets this value as:

• Rack travel, if Steering Input = Length

• Steering-wheel angle, if Steering Input = Angle

Lower Steering Limit Enter a real value that fixes the lower limit of steer travel. Adams/Car interprets this value as:

• Rack travel, if Steering Input = Length

• Steering-wheel angle, if Steering Input = Angle

Left Wheel Fixed Height (optional)

Enter a real value that fixes the left vertical wheel-center height relative to the design configuration. For example, if you enter -50 mm, Adams/Car displaces the left wheel center 50 mm downward from its input position and then sweeps the steering from its lower to upper bound.

Adams/CarSuspension Analysis: Steering

630

Right Wheel Fixed Height (optional)

Enter a real value that fixes the right vertical wheel-center height relative to the design configuration. For example, if you enter -50 mm, Adams/Car displaces the right wheel center 50 mm downward from its input position and then sweeps the steering from its lower to upper bound.










The icon shows the difference between the vehicle and iso coordinate systems.If you use the iso coordinate system, and the left and right wheel heights are different, the results will vary slightly than if you use identical wheel heights but use the vehicle coordinate system.

When comparing the results obtained from the iso coordinate system and vehicle system, the results will be identical if the wheel heights are the same. The results will vary if the wheel heights are different. This is because of the way the tire forces are calculated in different coordinate systems, and specifically because the different orientation of the road-tire vector for each analysis.


631Dialog Box - F1 HelpSuspension Analysis: Steering







Adams/CarToggle Driveline Activity

632

Toggle Driveline Activity

(Standard Interface) Adjust Driveline Activity

Toggles the driveline (Drivelines) activity of a suspension subsystem, if a driveline is part of the suspension template.


Current Mode Select one of the following:

• Active - Activates the driveline.

• Inactive - Deactivates the driveline.

Note that Active/Inactive corresponds to the parameter variable driveline_active = 1/0 in the suspension template. See Parameter Variables.

Appendix

Adams/CarAdams/Car Solver

640

Adams/Car Solver The Adams/Car Solver is a demand-loaded library that consists of automotive-specific solver elements that are not supported in the standard Adams/Solver. Some of the elements modeled in the Adams/Car Solver include springs, dampers, bushings, conceptual susp

ension analyses, and suspension characteristics.

When the standard Adams/Solver is started and specific routines are required, the Adams/Car Solver is automatically loaded as an extension. You can also add your own extension by creating user-defined libraries as explained in Introducing Adams/Solver Libraries.

641AppendixAdams/Car Standard Interface

Adams/Car Standard Interface

Adams/CarAdams/Car Template Builder

642

Adams/Car Template Builder

643AppendixAnalysis Log File

Analysis Log FileAdams/Car names the analysis log file after the output prefix and an output suffix, depending on the full-vehicle analysis you selected. The log file contains information about the type and success of the analysis, date and user, analysis parameters, and the active subsystem used in the analysis.

Adams/CarCentroidal Inertia

644

Centroidal Inertia Centroidal inertia is inertia measured about the center of mass.

645AppendixCourse Marker

Course Marker When you create the assembly, Adams/Car creates a marker on the ground part. (Learn about Markers.) Because Adams/SmartDriver uses this marker to determine the position, velocities, and accelerations of the vehicle, the orientation of this marker is critical.

You should orient it depending on the road data file that you want to use for your Analysis: the positive x-axis of the course marker should point towards the positive direction of travel in the road data file.

Adams/CarData-Driven Analysis

646

Data-Driven AnalysisThe inputs for a data-driven analysis are defined in the driver_loadcase_file used in the analysis. A driver loadcase specifies inputs to the vehicle as: steering value, desired velocity, braking pressure, and so on.

Adams/Car creates an event file (.xml) that defines the analysis and the different parameters. It uses the .xml file for the analysis and then leaves it in the working directory so you can refer to it as needed.

See Working with Event Files (.xml).

647AppendixDrivelines

Drivelines If you modeled a driveline in the suspension template, you can toggle the driveline between active and inactive states.

Adams/CarError Checks

648

Error Checks To avoid nonphysical conditions, you must carefully select the desired mass and inertia values. Sometimes, Adams/Car cannot match the desired aggregate mass properties you input because the properties result in negative mass or in negative principal inertias for the part you select to modify.

For example, assume the aggregate mass of the model is 2000 kg, and the mass of the part is 400 kg. If you input a desired aggregate mass of 1500kg, then to match the desired mass the modified part must have a mass of (400+(1500-2000))=-100 kg, which is nonphysical. Two conditions lead to error:

• If the calculated mass for the part < 0, Adams/Car cancels the adjustment.

• If the principal inertias < 0, Adams/Car adjusts the mass and the location of the center of gravity (CG) of the part (so that the overall location of the CG of the model is the one you entered), but does not modify the moments of inertia.

649AppendixFull-Vehicle Assembly

Full-Vehicle AssemblyA full-vehicle assembly is comprised of:

• Front suspension and front wheel subsystems

• Rear suspension and rear wheel subsystems

• Steering subsystem

• Body subsystem

It can also consist of many other subsystems and nonstandard subsystems. For example, you may want to create an assembly that contains particular control systems.

Adams/CarGeneral Parts

650

General Parts General parts are rigid parts that you define using their location, orientation, mass, inertia, and center of gravity. If you want to, you can add geometry to general parts. Adams/Car uses either geometry-based or user-entered information to determine mass properties for general parts.

651AppendixInterface Part

Interface Part An interface part is a massless general rigid part that is rigidly fixed to a specified node. You can use interface parts to connect flexible bodies to the rest of your mechanism.

Adams/CarKeyword

652

KeywordA word that represents a command or parameter.

653AppendixLoadcase Files

Loadcase Files Loadcase files are text files that contain the vertical wheel travel and other parameters needed to control a suspension analysis.

Adams/CarLongitudinal Acceleration Controller

654

Longitudinal Acceleration ControllerThe longitudinal acceleration controller uses vehicle information (position, velocity, gear, engine speed, and so on) as feedback to control the longitudinal acceleration of the vehicle. The controller is able to control both positive (acceleration) and negative (deceleration) acceleration.

The longitudinal acceleration controller forms part of the Driving Machine that is used to control the majority of standard full-vehicle analyses.

655AppendixLongitudinal Deceleration

Longitudinal Deceleration This parameter controls the brake signal: a longitudinal closed-loop controller acts on the brake to maintain the desired rate of change of longitudinal velocity.

Adams/CarMode of Simulation: Graphical

656

Mode of Simulation: GraphicalWhen you set Mode of Simulation to graphical, your template-based product uses the internal Adams/Solver to run the Analysis.

657AppendixMount Parts

Mount Parts Mount parts are massless parts that attach to other parts. By default, mount parts are fixed to ground. Mount parts represent the vehicle body or subframe and act as place holders.

When you create a mount part, Adams/Car automatically creates an input communicator for it of class mount. The input communicator requests the name of the part to which the mount part should connect. If Adams/Car finds a matching communicator during assembly, it replaces the mount part with the part that the output communicator indicates. The replacement part is from another subsystem. If Adams/Car finds no matching output communicator, it replaces the mount part with the ground part.

Adams/CarNotes About Dependent/Independent Suspension Curves

658

Notes About Dependent/Independent Suspension CurvesThe suspension analysis dialog box calls an analysis submission macro that executes the generate_scf.exe utility using a system command. The generate_scf.exe utility creates suspension characteristics files (scf) by reading and extracting data from different request files. The amount of information written to the scf file depends on the number and type of request files it finds in the working directory. It also creates a log file that lists warnings and execution errors.

After the dialog box successfully completes the analyses, it copies the generated suspension characteristic file to the suspension_curves.tbl directory in the Default Writable Database. It also leaves a copy of the scf file in the local working directory for future examination.

You can also invoke generate_scf.exe from the command line as a stand-alone utility:

generate_scf.exe output_prefix_scur flag

where:

• output_prefix_scur identifies all the different requests

• flag identifies whether the suspension is independent or dependent

The generate_scf.exe utility uses one of the .nam files, that Adams/Car creates, as the key to determine the request ID corresponding to a given result name; to successfully execute generate_scf.exe, the name file *_pw0.nam must be in the working directory.

The type of results and components that generate_scf.exe is looking for in the different requests is predetermined, and you cannot change it. It relies on the definition of the suspension characteristic requests as they are formulated in the .__MDI_SUSPENSION_TESTRIG.

Dependent and independent suspension curves are very different. Adams/Car does not know if your suspension is dependent or independent. It is up to you to use the appropriate dialog box that generates suspension curves.

659AppendixRoad Data File

Road Data FileA road data file (.rdf) specifies the road model and the associated data to be used during the Adams/Solver Simulation. The road data file describes the three-dimensional road geometry with which the tires interact.

Adams/CarRoll & Vert. Force

660

Roll & Vert. Force(Standard Interface) Simulate -> Suspension Analysis -> Create Loadcase -> Select Loadcase Type = Roll & Vert. Force

Creates a roll and vertical force loadcase file (see Loadcase Files).


Roll Angle Specify the Roll Angle.

Total Vertical Force Specify the total vertical wheel force available to both the left and right actuators.

Fixed Steer Position(optional)

Define the steering positions held during the Simulation.








661AppendixRoll Angle

Roll Angle Roll angle is measured by the inclination of the Test Rig tables.

Adams/CarSetting Initial Toe and Camber Variables

662

Setting Initial Toe and Camber Variables

To set the initial toe and camber variables to the desired values:

1. From the Adjust menu, point to Parameter Variable, and then select Modify.

The Parameter Variable Modification dialog box appears.

2. Right-click the Parameter Variable text box, point to Variable, point to Guesses, and then select a toe variable.

Adams/Car retrieves the original variable value.

3. Replace the original value with a new value.

4. Select Apply.

5. Repeat Steps 2 and 3, this time modifying a camber variable.

6. Select OK.

663AppendixStatic Load

Static Load(Standard Interface) Simulate -> Suspension Analysis -> Create Loadcase -> Select Loadcase Type = Static Load

Creates a static load loadcase file. Learn about loadcase files with Setting up Suspension Analyses.



Cornering Force Enter values for the left and the right cornering force.

Braking Force Enter values for the left and the right wheel that fix the upper bound and lower bound of the braking force applied between ground and test rig wheels at the Test Rig wheel center of mass location.

Traction Force Enter values for the traction force.

Vertical Length/Force Enter values for the vertical wheel input.

Vertical Input Select one of the following:

• Contact Patch Height

• Wheel Center Height

• Wheel Vertical Force

• Actuator Vertical Force

Overturning Tor. Enter values for the overturning torque.

Roll. Res. Torque Enter values for the rolling resistance torque.

Damage Force Enter values for the damage force.

Damage Radius Enter values for the left and right damage radius.




Adams/CarStatic Load

664

Steer Upper/Lower Limit Enter values that fix the upper bound and the lower bound of the rack displacement (if Steering Input is Length), or of the steering wheel (if Steering Input is Angle). Positive rack displacement moves the rack towards the vehicle's right side. Positive steering-wheel angles rotate the steering wheel counterclockwise, typically steering the vehicle to the left.

Coord. System Select one of the following:





665AppendixSteer Axis

Steer Axis You need the steer axis of a suspension to compute suspension characteristics such as caster angle, kingpin inclination, scrub radius, and caster moment arm.

When you create a suspension template in Adams/Car, you must select the method that Adams/Car will use to compute the steer axis, and provide the necessary input information. You can use two methods to calculate suspension steer axes:

• Geometric - Adams/Car calculates the steer axis by passing a line through the points you selected in the Coordinate Reference text boxes.

• Instant axis - Adams/Car calculates the steer axis as the instant axis of rotation of the wheel carrier parts. To calculate the steer axis, in physical terms, Adams/Car first locks the spring travel and applies incremental steering torque or force. Then, from the resulting translation and rotation of the wheel carrier part, it is able to calculate the instant axis of rotation for each wheel. The instant axis of rotation corresponds to the steer axis.

Adams/CarSteering

666

Steering(Standard Interface) Simulate -> Suspension Analysis -> Create Loadcase -> Select Loadcase Type = Steering

Creates a steering loadcase file. Learn about loadcase files with Setting up Suspension Analyses.


Steering Limit Enter values for the upper and lower bounds of steering input.

Fixed Wheel Center Enter values for the wheel vertical positions.








667AppendixSuspension Assembly

Suspension AssemblyAn suspension assembly is comprised of suspension and steering subsystems and a suspension Test Rig.

A steering subsystem, however, does not have to be present in a suspension assembly. For example, a rear suspension assembly, in most circumstances, would not contain a steering subsystem.

Adams/CarSuspension Parameters

668

Suspension ParametersSuspension parameters describe the vehicle in which you want to use the suspension. Adams/Car uses, for example, the parameters wheelbase, cg_height, and sprung mass to calculate the fore-aft weight transfer during braking and acceleration. Adams/Car then uses weight transfer to calculate dive and lift suspension characteristics.

Once you set the parameters in an Adams/Car session, Adams/Car uses those settings for all suspension analyses until you reset the parameters.

669AppendixTorque versus Engine Speed and Throttle Position

Torque versus Engine Speed and Throttle Position

Adams/CarWelcome Dialog Box

670

Welcome Dialog Box

Image courtesy of Wyatt Turner Design (http://wtdesign.flashex.com/)

http://wtdesign.flashex.com/

671AppendixWheel Travel

Wheel Travel (Standard Interface) Simulate -> Suspension Analysis -> Create Loadcase -> Select Loadcase Type = Wheel Travel

Creates a wheel travel loadcase file. Learn about loadcase files with Setting up Suspension Analyses.


Parallel/Opposite/Single Select a type of wheel travel.

Bump Travel Enter the upper limit of wheel-center displacement.

Rebound Travel Enter the lower limit of wheel-center displacement.

Fixed Steer Value Enter a constant value for the steering input.







If you select Opposite, Adams/Car enables the following option:





If you select Single, Adams/Car enables the following options:

Fixed Wheel Center Enter a constant value for the wheel vertical position.

Side Select one of the following:

• Left

• Right

Adams/CarWheel Travel

672

using adams/car - md adams 2010

Documents