Training Manual for SimWind2July 2016

Contact Information:McClean Anderson300 Ross Avenue

Schofield, WI 54476USA

Phone: +1 (715) 355 3006Fax: +1 (715) 359 0900

On the Web: www.mccleananderson.comEmail: info@mccleananderson.com

© 2013 McClean Anderson Inc., All Rights Reserved. All information contained in this document is believed accurate at the time of printing. All trademarks belong to their respective owners.

Important note: this manual contains confidential technical information on McClean Anderson software and control systems and is only intended for use by McClean Anderson customers for the operation of our machines. Disclosure of this information to third parties is prohibited without express written consent from McClean Anderson.

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1 Installation, Configuration and Start-Up...........................................................................31.1 Installation..................................................................................................................31.2 Start-Up......................................................................................................................41.3 Configuration.............................................................................................................4

2 Introduction to SimWind2 Interface.................................................................................42.1 Panel regions..............................................................................................................5

3 Files...................................................................................................................................74 Creating a Wind................................................................................................................9

4.1 Generating Fiber Path..............................................................................................104.1.1 Generating Helical Fiber Path...........................................................................104.1.2 Generating Circumferential Fiber Path.............................................................124.1.3 Generating Bottle Fiber Path............................................................................144.1.4 Generating Non-Linear Fiber Path....................................................................17

4.2 Selecting Path Pattern .............................................................................................234.3 Generating Motion...................................................................................................25

4.3.1 Machine Offsets................................................................................................264.3.2 Payout Eye Tooling Options.............................................................................264.3.3 Axis in Use / Axis Velocities............................................................................284.3.4 Override ...........................................................................................................284.3.5 Rate Envelope...................................................................................................28

5 Chain/Transition Wind....................................................................................................305.1 Transition Motion Files............................................................................................31

5.1.1 Segment Flags...................................................................................................325.2 Transition Path Files................................................................................................335.3 Do Not Transition....................................................................................................345.4 Chain File Tips and Troubleshooting......................................................................34

6 Viewing and Editing Motion..........................................................................................356.1 Overview of motion format ....................................................................................36

6.1.1 Mandrel - The Timekeeper...............................................................................366.1.2 Virtual Mandrel [VM].......................................................................................376.1.3 Rate Envelope...................................................................................................37

6.2 View and Edit Motion in Graph...............................................................................376.2.1 Selecting Axis to Display..................................................................................38

6.3 Editing Motion in Graph..........................................................................................396.4 Zoom Tools..............................................................................................................40

6.4.1 Zoom-in.............................................................................................................406.4.2 Zoom-out...........................................................................................................41

6.5 Steps involved in Editing.........................................................................................416.5.1 Deleting Motion Points.....................................................................................436.5.2 Adding Motion Points ......................................................................................446.5.3 Transform Tools................................................................................................46

6.6 View and Edit Motion in Table ..............................................................................486.6.1 Editing Motion via the Table............................................................................51

7 Export/Import CSV.........................................................................................................537.1 Export Motion .........................................................................................................537.2 Import Motion..........................................................................................................53

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7.3 Format of CSV.........................................................................................................548 Visual Rendering............................................................................................................559 Motion Filtering..............................................................................................................58

9.1 Basic Filter Parameters............................................................................................599.2 Additional Filter Parameters....................................................................................639.3 Advanced Filter Parameters.....................................................................................65

1 Installation, Configuration and Start-Up

1.1 Installation

The first step in installing SimWind2 requires the user to navigate to and download the installation package from a download link. Each Operating System [32-Bit and 64-Bit Windows] has a separate download link. The installation package is downloaded as a .zip file. This downloaded file needs to be unzipped to access the contents in the installation folder.

The installation folder has the name: SimWind_xOS_Install, where xOS is either x32 or x64 depending on the operating system platform.

The installation folder has the following installation files. SimWind2 requires the user to install all the three files.

Java Run Time environment Driver for hardware based protection keySimWind2Installer

Java Runtime Environment [JRE]: SimWind2 requires the JRE to run. Installing the JRE is straightforward. Double click on the jre-xxxx-windows-xOS.exe to bring up the installation setup for the JRE and follow the installation procedure.

Driver for hardware based protection key: Make sure there are no hardware key plugged to the system. Double click on Sentinel Protection Installer xxxx.exe to bring up the installation setup for the hardware key driver and follow the installation procedure.

SimWind2Installer: Double click on SimWind2xOS.exe to bring up the installation setupfor SimWind2 and follow the installation procedure.

On successful installation of the JRE, hardware key driver and SimWind2, the SimWind2icon is created on the Desktop and it is ready to be launched.

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Note: The download link can be obtained by contacting personnel at support@mccleananderson.com

1.2 Start-Up

SimWind2 can be launched by clicking on it's icon (see Figure 1) located on the Desktop.

1.3 Configuration

Before SimWind2 can be used, it needs to obtain the parameters of the machine that will execute the program. These are stored in .mct files. Each machine built is given a specificmct file. The mct file is given the name of the machine’s serial number (e.g. “j1234.mct” where j1234 is the machine number). When executing the software for the first time, or ina facility which has different types of McClean Anderson winders, users need to select the machine for which they wish to produce programs. The software remembers and uses this configuration until a new configuration file is loaded.

To load a new .mct file the user navigates to Config > Load New MCT in the Main Menu. This will bring up a typical windows file open dialog box. The user will then need to navigate through folders and select the appropriate .mct file.

After a .mct file is loaded, the user has to restart the software for the changes to take effect. The users can view the .mct file by navigating to Config > View Current MCT

2 Introduction to SimWind2 Interface

SimWind2 has a simple and intuitive application user interface. The interface has three panel regions - main panel, file panel and the feedback panel. Each of these are discussed in Section 2.1. Program control is provided through a set of menus. Certain tasks can be accessed quickly with the help of toolbars and context menus. The context menus are specific to the panel regions and the different objects within the interface. They are displayed by clicking on the right mouse pointer button on the region or object. Menu and toolbar items are enabled or disabled depending on the wind module and the active window.

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Note: When upgrading to a newer version - it is recommended that any currently installed version of SimWind2 be uninstalled. Sometimes it is also necessary to uninstall the hardware key driver. This can be achieved by using the standard Windowsuninstall methods in Program and Features.

Figure 1: SimWind2 icon.

The user can work on multiple files and file types at the same time and switch between them at any point. This is done by selecting the file in the File panel, which is located on the left side of the main window. Feedback is provided in the form of error, information, help and exception messages. Errors are also displayed next to the text boxes when incorrect parameters are entered.

2.1 Panel regions

Figure 2: Main panel displaying various windows.

Main Interface Panel: The main interface panel contains all windows related to a particular wind or motion that is being worked on.

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Figure 3: Main panel with motion displayed as graph. Also shown is the context menu for the graph.

Figure 4: Main panel with motion displayed as table. Also show in the context menu for the table.

File Panel: The panel contains the list of active files being worked on. The files are organized by their file types. The user can switch between the files by clicking on the file names. This updates the Main Panel with all the windows specific to the file. The File Panel has a context menu, which allows the user to do file operations such as Save, SaveAs, Close and Save and Close.

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Feedback Panel: The feedback panel contains the messages related to the file currently active. There are four different types of messages that are displayed.

Information Message: Describes the general information regarding a current event.

Error Message: Describes an error associated with an event. This usually means there were errors in the entered parameters or a solution for the entered parameter could not be reached. The errors can be fixed by following the instructions contained in the error message. The error messages have an error code paired withthem. If the user is unable to resolve the error the support team can be contacted with the error code for a solution.

Exception Message: Describes an exception condition. These are quite rare. This usually means the error handling failed or/and there is a bug in the code. The user can contact the support team for a fix.

Help Message: These are paired with Error and Exceptions to help resolve the issue.

3 Files

SimWind2 introduces a new file format with new extensions for each wind module. The format and the extensions for the motion files (.mmt and .chn) are same as in Composite Designer. This allows backward compatibility of the motion files.

Composite Designer wind module files can be converted into SimWind2 files with the help of the Batch File Converter tool which is included in SimWind2. This can be accessed by navigating to Tools > Convert CD Files in the Main Menu. This opens a newwindow as shown in Figure 5.

The user converts the Composite Designer files by dragging and dropping individual filesor entire folders in the File Panel of the convert tool. The user can also navigate to the file and folder using the File > Load Files / Folder menu. The tool recursively searches the folders for all Composite Designer wind files and creates new SimWind2 files in the same folder maintaining the file and directory structure.

The Convert tool also displays the wind parameters being read and placed into the new file format for inspection.

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File Extension Reference:

The following table lists the file extensions used for each module.

.ang Angle definition file - used to establish fiber angle and/or wind startand end points for non-linear winds.

.aux Auxiliary output file - used to control Flexwind in tandem with amotion file to define conditions for controlling auxiliary outputs.

.bld Dr.Blade control file – generated by Coordinator module in SimWind2to control the Dr. Blade through Flexwind.

.btw Bottle wind parameter file.

.chn; *flt.chn Chain motion file – a multiple segment motion file used by Flexwind.(i.e., several .mmt files chained together in sequence).

.ciw Circumferential wind parameter file.

.chw Chain/Transition parameter file – used to chain multiple segements toresult in either path based or motion based compound motion file withthe .chn extension

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Figure 5: Batch convert Composite Designer files to SimWind2 files.

.hlw Helical wind parameter file.

.mct Machine configuration file - contains information of the machine to becontrolled. This is used by SimWind2 to make machine specificprograms.

.mdf Mandrel definition file - used to describe the geometry of the givenmandrel.

.mfp Motion filter parameter - keeps track of filtering parameterscorresponding to a current motion file.

.nlw Non-Linear wind parameter file

.mmt; *flt.mmt

Machine motion file - a single segment motion file used by Flexwind.

.pth Path file - contain a list of sequential coordinates describing a singlecircuit of fiber path across the surface of a mandrel; used whengenerating motion and for 3D rendering purposes.

.ten Tensioner control file - generated by Coordinator module inSimWind2 to control the Dr. Blade through Flexwind.

4 Creating a Wind

When creating a wind program in SimWind2, the user needs to follow the same basic sequence of steps. Step 1Select required Wind Type. At present, SimWind2 allows the following wind types – Circumferential, Helical, Bottle, Non-Linear, Chain-Transition, Unidirectional and Zero-Degree Wind.

Each of these winds are explained in detail in separate sections.

Step 2Enter the Wind Parameters. This includes part geometry and parameters such as bandwidth and fiber angle. This is discussed in detail in Generating Fiber Path (Section4.1)

Step 3Generate the fiber path patterns. These fiber paths will vary by minor differences. This will result in different wind patterns and other physical wind characteristics. The user canstudy and sort these various possible paths and select the path that will best match the design at hand. In some cases, the user will need to iterate this with different wind parameters to establish a stable or more optimal path. This is discussed in detail inGenerating Fiber Path (Section 4.1) and Selecting Path Pattern (Section 4.2)

Step 4Visualize the selected path pattern in 3D. This is discussed in detail in Section 8.

Step 5

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Enter Machine Motion Parameters. This includes establishing the desired clearances the machine should maintain from the surface of the part, along with determining various types of envelopes to control machine motion. This is discussed in detail in Generating Motion (Section 4.3)

Step 6Examine and tweak the resulting motion. Particularly with complex parts, the resulting motion may require some user-assisted post-processing to improve machine performance and smooth any spikes in machine motion. This is discussed in detail in Viewing and Editing Motion (Section 6)

Step 7At this point the user can also run the filtering function to remove noise and vibration andincrease throughput on complex parts. This is discussed in detail in Motion Filtering (Section 9)

Step 8Execute the program. In some cases, this may be done prior to any motion post-processing since the user may first wish to establish if a particular path is stable.

Once these steps have been completed, the user should have a viable parts program, which is well suited to generating the desired component. This usually requires some iteration between the steps. As the designer gains experience, the process will become more rapid and the user will gain insight into critical design parameters and often be able to quickly form judgments ranging from determining if a part is well suited to filament winding, to selecting the appropriate wind parameters.

4.1 Generating Fiber Path

Generating fiber path patterns is the first step in creating a wind program.

4.1.1 Generating Helical Fiber Path

To begin a new Helical wind program navigate to File > New > Helical Wind. This loadsthe wind dialog where the user has to enter wind parameters. Each of the wind parametersare explained with the help of a diagram, see Figure 8 and their descriptions below.

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Note: Generating chain files is a somewhat more complex sequence of events involving generating and testing individual segments and then combining these and performing some additional tweaking. This is discussed in detail in Chain/Transition Wind (Section 5)

Figure 6: Creating a new Helical Wind

Figure 7: Helical Wind dialog window.

Figure 8: Helical Wind parameters.

Fiber Start Position: The location of the carriage relative to the mandrel origin where the helical path will begin.

Fiber End Position: The location of the carriage relative to the mandrel origin where thehelical path will end.

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Mandrel Diameter: The diameter of the mandrel.

Fiber Bandwidth: The bandwidth of the fiber.

Turnaround Range: The region over which the helical fiber path is allowed to transitionfrom the desired fiber angle towards 90 degrees. This range is also referred to as an acceleration range because it affects the rate at which the carriage axis is required to change directions for the given pattern. Over this distance, the carriage accelerates from zero to the programmed speed and vice versa. It is recommended that at least one (1) inch of linear range be used for every 20 fpm of carriage speed.

Fiber Angle: The angle between the fiber's orientation at the surface of the mandrel and an intersecting surface line that is parallel to the mandrel’s axis of rotation

End Dwell: The amount of mandrel rotation in degrees at the start and the end position before the carriage begins to move towards the opposite direction.

Path File Threshold: This parameter establishes how often the software generates path coordinates. The software will calculate a path point for this increment of mandrel rotation. Typical range for this value is between 5 and 30 degrees. Choose the lower end of the range for simpler winds.

4.1.2 Generating Circumferential Fiber Path

To begin a new Circumferential wind program navigate to File > New > Circumferential Wind. This loads the wind dialog where the user has to enter wind parameters. Each of the wind parameters are explained with the help of a diagram, see Figure 10 and their descriptions below.

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Note: The fiber start and end locations are not bandwidth compensated i.e. they describe the fiber centerline. The final wrap will be approximately 1 fiber bandwidth wider than entered.

The wind can start at either end of the mandrel. If the fiber start is greater than the fiber end Position, the wind will start near the tailstock and move towards the headstock. However, the recommended way to reverse the wind is during path selection.

Figure 9: Circumferential Wind dialog window.

Figure 10: Circumferential Wind parameters.

Fiber Start Position: The location of the carriage relative to the mandrel origin where the helical path will begin.

Fiber End Position: The location of the carriage relative to the mandrel origin where thehelical path will end.

Mandrel Diameter: The diameter of the mandrel.

Fiber Bandwidth: The bandwidth of the fiber.

Fiber Start Dwell: The amount of mandrel rotation in degrees at the fiber start position before the carriage begins to move towards the fiber end position.

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Note: See Note in Helical winds regarding fiber bandwidth compensation and the start and end position of fiber.

Fiber End Dwell: The amount of mandrel rotation in degrees at the fiber start position before the carriage begins to move towards the Fiber End Position.

Coverage Strokes: A Stroke is a single layer of full coverage from the Fiber Start Position to the Fiber End Position. With an even number of strokes - the result is cyclic i.e., the wind starts and ends at the Fiber Start Position. With odd number of coverage strokes, the machine ends at the Fiber End Position.

4.1.3 Generating Bottle Fiber Path

To begin a new Bottle wind program navigate to File > New > Bottle Wind. This loads the initial panel where the user can enter wind parameters. Each of these wind parametersare explained with the help of diagrams, see Figure 12 and Figure 13 and their descriptions below.

Figure 11: Bottle Wind Parameters

The Bottle Wind module handles two types of bottle dome shapes, Ellipsoidal and Isotensoid. Both bottles have a cylindrical section and domes on both ends. The

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Note: The given dwells are applied at the end of every stroke. For example, if the user has the Fiber Start Dwell set to 360, the Fiber End Dwell set to 180, and the number ofstrokes set to 2 - the machine will dwell 360, move from the Fiber Start Position to theFiber End Position, dwell 180 then dwell 360, move from Fiber End Position to Fiber Start Position, dwell 180, and then Stop. If other dwell characteristics are desired, these could be generated via chaining circ winds together.

ellipsoidal dome, when cut along the mandrel axis, has an elliptical shape for its domes while the isotensoid dome consists of two 90-degree circular arc segments and a flat end to connect the two. The diagrams below show examples of the two bottle shapes. In general, ellipsoidal shapes tend to generate better machine motion because they have fewer discontinuities. Often, bottles with an isotensoid shape are more easily wound using an ellipsoidal approximation.

The dialog box has four tabs along the bottom of the parameters. In addition to the two shapes already discussed, the user can also select planar winds for each shape. With planar winds, the machine will try to wind from pole to pole and the fiber angle is automatically adjusted to the lowest possible.

Mandrel Diameter: The diameter of the mandrel.

Cylinder Length: The length of the cylindrical section of the bottle excluding the dome ends.

Ellipsoidal Bottles:

Figure 12: Ellipsoidal Bottle Wind Diagram

Each of the parameters is explained below.

Left Dome Width: The left dome width.

Right Dome Width: The right dome width

The dome widths define the shape of the ellipse. If the dome width is set to the mandrel radius (i.e. ½ of mandrel diameter), then the domes become spherical. Smaller values give flat domes while larger values give pointy ones.

Isotensoid Bottles:

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Figure 13: Isotensoid Bottle Wind Diagram

For Isotensoid bottles, Left and right dome polar opening replace dome width. These define the diameter of the flat ends of the Isotensoid shape. As the polar opening approaches zero, the end becomes spherical; as it approaches the mandrel diameter, the end becomes cylindrical.

Dome Evaluation Points: Establishes how many sample points are taken to describe the profile of the dome on both ends of the mandrel. This affects how accurately the part will be calculated in software, the accuracy of path, and consequently the rendered part and motion. In general, a value around 50 will produce good results and does not require further adjustment.

Fiber Bandwidth: The bandwidth of the fiber.

Fiber Angle: The angle between the fiber’s orientation at the surface of the mandrel and an intersecting surface line that is parallel to the mandrel’s axis of rotation

Left Polar Opening: The opening in the fibers at the left end of the part.

Right Polar Opening: The opening in the fibers at the right end of the part.

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Note: The Polar Opening usually requires some adjustment to achieve a stable (i.e. small dome slip factor) wind. The appropriate value will first depend on the physical layout of the mandrel (e.g. the machine obviously can’t wind through any shaft protruding from the ends). Beyond this, the user may need to decide on the appropriatetrade-offs between polar opening, fiber angle, and fiber stability. If the left and right openings are significantly different in size, this can pose a problem to stability. In suchcases, the user may wish to examine a Non-Linear, which allows for a gradual change in fiber angle along the cylinder. The following section also covers topics of path stability in greater detail. Polar opening takes fiber bandwidth into account (i.e. it is not based on the fiber center line), so the desired opening value should be used.

Cylinder Threshold: Establishes the frequency of path solution points along the Cylinder length.

Dome Threshold: Establishes the frequency of path solution points along the dome length.

4.1.4 Generating Non-Linear Fiber Path

Non-Linear winds are used to generate highly complex helical and hoop patterns on axis-symmetric mandrels other than bottles and tubes. While non-linear winds are quite powerful, several iterations are required to establish stable fiber angles at various points along the mandrel. The resulting motion often requires some degree of post processing. This is discussed in detail in Section 6 .

To begin a new Non-Linear wind program navigate to File > New > Non-Linear Wind. This loads the initial panel where the user can enter wind parameters.

The next step is to establish a mandrel profile. This is done by importing mandrel information either from a .dxf file or from a formatted .csv file. These formats are discussed in detail in Section 4.1.4.3 and Section 4.1.4.4.

To load the mandrel profile - navigate to Mandrel > Import Mandrel menu (Figure 14). This brings up a File-Load Dialog. The user has to select from either .dxf or .csv format from the file extension drop down list. The user then has to navigate and load the mandrelprofile. At this point the user is presented to enter the Mandrel Import Threshold using a dialog box (Figure 15). This value determines how often the mandrel radius is sampled to

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Note: Before doing any post processing on the motion - be sure to exhaust all iterations to establish a stable fiber path by altering the angles and their locations along the mandrel and also to change the wind and the motion parameters.

Note: The Threshold parameters are in units of fiber length (i.e. inches or mm). Path solution points are used during visual part rendering and later to generate machine motion. If these values are too small, the resulting path can have an excessive number of points (generally, a complex single segment should not require more than a hundredpoints or so). This can also lead to some motion stability issues in transition regions. Conversely, if this value is too large, the path may not cover all the nuances of the partmotion and can be even more prone to motion instability in some types of transition regions where the spacing between motion coordinates becomes uneven. This is often a problem on low-angle winds. In general, these values will require adjustment when there are major size differences between parts.

Typical values for the Dome Threshold are around 1/20th the part diameter and about 1/20th the cylinder length for the Cylinder Threshold.

create the profile i.e., establish the distance between axial samples. For example, a value of 0.25 units - samples the mandrel radius at roughly every 0.25 units, where units is mm or inches.

Figure 14: Import mandrel menu.

Figure 15:Mandrel import threshold dialog.

Once the mandrel profile is loaded, the user should see the mandrel profile as a graph (Figure 16) or a table (Figure 17) depending on the chosen view format. The view format can be changed by using the Mandrel menu.

Figure 16: Mandrel definition as a graph.

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4.1.4.1 Wind Parameters

Figure 17: Wind parameters and the mandrel definition as a table.

Wind Path Options:

The Non-Linear wind module offers 3 different types of path, each of which can be chosen by the radio buttons on the bottom right of the parameter panel.

Helical Path: Similar to a bottle wind or helical wind, depending on mandrel shape.

Circumferential Path: Similar to a hoop wind on a cylinder

Planar Path: Fiber path is a near zero-degree wind from end to end.

Mandrel Profile Table:

The Mandrel Profile is described by the Axial and the Radial values through linear interpolation.

Axial Column: The axial value is measured along the axis of mandrel rotation.

Radial Column: The radial value gives the mandrel’s radius at the particular axial point. The mandrel should begin and end with a radius of zero (very abrupt changes are acceptable - e.g. a radius of 0 to start and 10 inches after 0.0001inches down the axis).

Angle Column: The angle column describes the target fiber angle at various locations along the part. Appropriate values depend on the type of wind and also on the desired fiber path.

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4.1.4.2 Entering the target angles

Once the Mandrel profile is loaded, the user can add target angles at different locations inthe angles column.

For helical winds, the user can mark the start and end of the wind by placing a 90 in the angle column. Alternatively, the start and end of the wind can be established by setting the polar openings in the main parameter window. In both cases, the user must enter at least two additional angles between these extremities. The fiber path is calculated by gradually varying the fiber angle so that it reaches 90 degrees at the ends of the dome (or in the turnaround region) and attains the specified angle(s) at the given entry locations.

For planar winds, the angle column is largely irrelevant. However, the user must place at least two values in it - these must lie between the points which correspond to the polar opening entries (the radius values at the entry rows should exceed half the corresponding pole diameter). The software uses them to establish the boundary between the dome and cylindrical portions of the wind. The angle values themselves are ignored (the planar wind always attempts to generate angles near zero).

For circumferential winds, the user needs to enter two values in the angle column signaling the start and end of the wrap. The values themselves are irrelevant (generally, the recommended values are 1 for the starting point and 2 for the ending point). The fiber path will begin at the smaller of these values (so to start winding closer to the tailstock, place the larger value first in the table).

Once the user has completed mandrel definition table data entry, they can finalize the data by clicking on the Accept Edit button on the menu. It is important to finalize the mandrel data after edits of the mandrel table.

Fiber Bandwidth: The bandwidth of the fiber.

Z-Axis Coverage Location: Non-linear winds can have varying radii and fiber angles. Because of this, the software can generally only provide full fiber coverage at a particularradius and fiber angle. Z axis coverage location establishes this location along the mandrel axis (Z-axis) at which the software generates full coverage. Other location on themandrel will have gaps or over laps.

Cylinder Threshold: Establishes the frequency of path solution points along the cylinderlength.

Dome Threshold: Establishes the frequency of path solution points along the dome Length.

Left and Right Polar Opening: Establishes the fiber opening diameter at the left or right end of the part. This option is only available when generating a helical or planar wind.

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Start and End Dwell: These determine how many degrees the mandrel should rotate at the start and end of a circumferential wind before carriage motion commences. This option is only available when generating a circumferential wind.

Because the user directly specifies angles for helical non-linear winds, this can lead to some confusion about the exact definition of openings and thresholds. Actual entry of angle data is covered in subsequent sections, but the start and end of winds can be specified in one of two methods:

Method 1: The user can enter 90 degrees in the angle column of the mandrel data to mark the start and end points of the wind. Between these points, the user must enter at least 2 additional angle values. In this case, the polar opening values are ignored and the software only uses the angle data to establish the start and end of the wind; also, the windwill not have any polar region - the path generation algorithm will only use the cylinder threshold value.

Method 2: The user can enter the desired polar opening. The software will then automatically interpolate a 90-degree point into the mandrel table (no entry is actually made, it simply determines where the mandrel diameter first reaches the given left opening and last reaches the right opening). The user must then add supplemental angle data in the angle column of the mandrel. At least two additional angles must be entered inthe angle column between the resulting start and end points. In this case, the dome threshold value is applied to the region between the polar openings and the closest angle entry. The cylinder threshold value will apply to the rest of the mandrel (between the outermost angle entries).

For planar winds, the software always uses the polar openings to establish the start and end of the wind. However, the user must still enter at least two angle values that lie within the region to be wound. Their actual value is ignored (although typically 90 is used), but their table location is used to determine the transition between the dome and cylinder threshold region. For a bottle, it would typically be placed at the transition point.For other shapes, the selection may be less obvious, but it should be thought of as marking a boundary. If it is set too close to the polar opening, this can result in poor motion.

While many of these parameters are similar to other types of wind programs, the remaining steps are unique to non-linear winds: editing the mandrel and angle data. Theseare done through a graphical and a spreadsheet interface.

If the user is satisfied with the general mandrel and wind parameters, he/she can generate the fiber path by pressing the “Calculate” button. If a circumferential wind is being generated, then no path selection is possible. The user simply enters the number of strokes and the relevant path file is generated.

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4.1.4.3 Format of .dxf file

The mandrel profile can be generated using Auto-CAD®, or a similar package capable ofgenerating .dxf files. Such files should remove all extraneous data and lines, and simply consist of the relevant mandrel profile. The profile should consist of discrete segment entities rather than polylines. These entities should be of type – line, arc, ellipse and circle.

4.1.4.4 Format of .csv file

The mandrel definition can be in a simple comma-separated values file containing the axial, radial and angle values separated by commas. The file should have the .csv extension. This file format can be opened with any spreadsheet program to be created, edited and imported back into SimWind2. Users can create the mandrel definition in a spreadsheet program by assigning the axial, radial and angle data into three separate columns. The user always has to make sure to save the spreadsheet file as a .csv file.

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Figure 18: A mandrel definition created in Auto-CAD as a .dxf file.

Shown in Figure19 is a mandrel definition as a .csv file, and the same file open in a spread sheet program.

4.2 Selecting Path Pattern

On successful completion of the Generate Path Patterns step, the user in presented with anew interface screen, which lists the different possible fiber path patterns. By default the fiber path patterns are sorted by the path deviation. The user can choose a different sort criterion by clicking on the column header. By selecting on the row and then clicking the Select Path button, the user can select the fiber path pattern they wish to convert into

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Figure 19: Mandrel definition as a .csv file.

motion. They may visualize the part in 3D to assist with this selection. At this point the .pth and .mdf files are written.

Figure 20: Path Selection.

Listed below is a brief description of the column headers.

Patterns: The number of patterns on the part i.e., the number of diamond patterns following a circumferential route around the Mandrel. With winds with domes, an alternate method is to count the number of points on the star like pattern which form at the poles. Larger number of patterns indicate a tighter weave.

Figure 21 and Figure 22 show 4 pattern and an 8 pattern respectively.

Circuits/Coverage: The number of carriage circuits (from the start to the end position and back again) needed to close the pattern.

Adjusted Bandwidth: The bandwidth adjusted to give complete coverage.

Adjusted Angle: The fiber angle adjusted to give complete coverage.

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Figure 21: 4 pattern Figure 22: 8 pattern

Natural Path Deviation: Indicates the relative deviation between the natural or base fiber path and the adjusted fiber path required for this pattern. The fiber angle is used as criteria for calculating the path deviation.

Lead/ Lag: Describes on which side of the original fiber later circuits will be placed. On a lead pattern, newer circuits are placed ahead of older ones in the direction of rotation (i.e. they come into view first as the mandrel rotates). On lagging patterns, they are placed behind older ones.

Figure 23: Lead / Lag

Start on Right End of Mandrel: Enabling the checkbox will reverse the normal path (and motion) of the wind.

4.3 Generating Motion

Once the user is satisfied with the wind path and pattern, a motion file can be generated. The motion file is executed on the Motion Control software - Flexwind. The motion files have a .mmt or .chn extension depending if it`s a single segment or multi segment program.

The Generate Motion dialog box is displayed on selecting the path pattern, as discussed in Section 4.2.

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Figure 24: Generate Motion

4.3.1 Machine Offsets

Origin Pattern Offset: The distance between the face of the mandrel or head-stock chuck (or mounting flange) and the start of the mandrel part, as used for fiber path calculation.

Payout Offset: The length of the payout tooling from the face of the mounting plate and the end of the tooling.

4.3.2 Payout Eye Tooling Options

Establishes the clearances indicating the distance to maintain between the fiber payout point and the surface of the part. The fiber payout point is generally defined as lying on the axis of eye rotation (for winders without eye rotation, it would lie inline with the crossfeed, perpendicular to the carriage axis) at the point at which the fiber leaves the tooling.

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Constant Position

The crossfeed is effectively disabled. The crossfeed is fixed at a given distance from the axis of mandrel rotation. In general, this value would be the maximum radius of the mandrel plus any additional desired clearance

Figure 25: Constant Position

Constant Tow

Establishes a clearance distance along a normal to the surface of the mandrel. In general, Constant Mandrel Clearance produces better results by allowing tighter control along both axes

Figure 26: Constant Tow

Constant Mandrel Clearance

The machine motion is scaled such that the fiber payout point is forced to lie on a curve which consists of the points closest to the part that maintain both the Side Clearance and the Top Clearance entered by the user.

Side Clearance

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Establishes the clearance in the carriage’s direction of travel. The desired value should bebetween the tip of the tooling / fiber payout point and the surface of the mandrel.

Top Clearance

Establishes the clearance in the Crossfeed’s direction of travel. The desired value should be between the tip of the tooling / fiber payout point and the surface of the mandrel.

Figure 27: Constant Mandrel Clearance

4.3.3 Axis in Use / Axis Velocities

Establishes which axes are enabled and set the max velocities based on what Rate Envelop option was chosen.

4.3.4 Override

Establishes the fixed positions for the disabled axes.

4.3.5 Rate Envelope

Establishes the type of motion rate envelope to use.

Constant Mandrel Speed: The rate envelope is based on having the mandrel operate at aconstant speed. The axes will then run as fast as needed such that the mandrel can maintain a constant speed.

Example: Assume a top mandrel speed of 150 rpm and a top carriage speed of 200fpm (feet per minute). If a particular portion of the wind would require the carriage to run at 250fpm to keep up with the mandrel, then all motion in that region would be slowed

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down to run at 80% of maximum, bringing the carriage back down to 200fpm and the mandrel to 120rpm.

Maximum Axis Speed: The rate envelope is based on the speed of each axis during the wind and actual program execution speed at each point in time will be determined by whichever axis has the most restrictive limit.

Example: For example, if mandrel top speed were 150rpm and a particular program had its lowest rate envelope reading at 45%, then the user would go back through the same motion generation process, again selecting “Maximum Axis Speed”, and enter a maximum speed for the mandrel of 67.5 rpm (45% of 150). The other axes would remain unchanged. The resulting motion should have a constant rate envelope indicating constantmandrel speed.

Constant Fiber Speed: This takes into account the maximum axis velocities and a target fiber speed. The software will then use approximation based on the fiber path to calculatethe length of fiber corresponding to each portion of machine motion. The rate at which this fiber segment is added becomes an additional - “Virtual Axis”.

The software then begins with a wind based on constant mandrel speed. It then uses this fiber-based “virtual axis” to determine the proper machine rate envelope (i.e. mandrel speed) for each portion of the wind in order to obtain the given constant fiber speed. Finally, the software will run another check – to determine if at any time any axis is violating its speed limit. If so, the entire rate envelope is rescaled by a factor of the worst violation found. The resulting motion will obtain constant fiber speed, but depending on any final adjustment, the actual fiber speed may be less than the entered value.

Example: As an example, assume a maximum mandrel speed of 150rpm, a maximum carriage speed of 100fpm, and a target fiber speed of 150fpm. The software would calculate an appropriate rate envelope to obtain 150fpm of fiber speed. During final evaluation, the software determines that for a particular portion of the wind, the mandrel would need to run at 200 rpm, while in a different portion, the carriage would need to runat 140fpm. No other violations are determined. The worst violation would be the carriage at 140/100 or 140% overspeed. The mandrel violation is 200/150 or 133% overspeed. Therefore, the entire rate envelope is rescaled by 100/140 or 71% resulting in an average fiber speed of 107fpm.

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CAUTION: When using a constant mandrel speed rate envelope, no speed limits are enforced on the remaining axes. Caution is advised when executing a program based on constant mandrel speed – particularly with large mandrels and high target speeds. With some parts (particularly low-angle winds), execution at too high a feed rate will cause the slaved axes to lose synchronization (due to axis saturation). If the resulting position error exceeds an internal bound, the machine will execute an emergency stop. For this reason, other rate envelopes, particularly “Maximum Axis Speed”, are recommended. Other means of obtaining constant mandrel speed are described below.

The Generate Motion button generates motion. Once completed, a message box informs the user on the success of generating motion and basic information on the wind is displayed. Clicking on the SimWind Logo on the feedback message box closes it.

Figure 28: Wind statistics feedback.

The data is shown at a feed rate of 50%. If the machine were to run at 100% wind time is cut in half.

5 Chain/Transition Wind

Chain/Transition Winds allow users to connect several files together and execute them in sequence. In addition, transition motion can be automatically generated to assist with the generation of smooth and stable motion from the end of one file to the start of the next.

To begin a new Chain/Transition program navigate to New > Chain/Transition Wind.

Figure 29: Chain/Transition Window

Add files to the list using a typical windows file open dialog box.

Remove the selected file from the list.

Reorganize the list by moving the selected file upwards on the list.

Reorganize the list by moving the selected file downwards on the list.

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One important concept in chaining files together is the transition segment. Between each segment, the software will automatically generate transition motion. The user can select one of three possibilities via the Transition Method.

5.1 Transition Motion Files

If this option is selected, the software will generate motion which connects the final state of one segment with the starting state of the next segment by directly extrapolating a trajectory based on various acceleration and velocity limited criteria (i.e. connect the velocities and positions of all axes). The intermediate path is not based on any consideration of either mandrel shape or fiber stability. This process tends to work well for connecting relatively short gaps in fairly similar winds. If this method is selected, the user would enter four parameters in the lower window portion as follows:

Transition Evaluation Points: Establishes the number of points to be extrapolated in each of the transition region to be calculated.

Transition Region Rate: Establishes a limit similar to a wind angle to the transition region – defined as limiting the carriage speed vs. mandrel speed (i.e. number of carriage position units per revolution of the mandrel).

Payout Eye Tooling Offset: Establishes a fixed offset to the crossfeed. This might be used if the designer believes clearance in the transition region to be inadequate (since transition motion does not consider actual mandrel shape, only smooth machine motion). Note that this offset is applied to the entire file, so it may cause problems in terms of pathstability on some shapes.

Transition Motion Tolerance: Establishes a unit-less smoothing factor. A value closer to zero makes the motion in the transition region more abrupt. High values allow acceleration to take place over the entire maneuver. Typical values are between 1 and 100.

Once the user has inserted all the files to be chained and set all the necessary parameters, he/she can click on the Generate Chain button. On a successful event a new interface panel appears allowing the user to select the number of circuits in the wind and also to setthe flags for each segment boundary. The flags apply to the start of the segment.

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Note: This transition segment flag interface panel appears for all types of chained motion files. Cells are enabled and disabled with respect to the type of segment and regions. For example, the Auto Find Path is only enabled for transition regions.

Figure 30: Set segment flags

5.1.1 Segment Flags

Each transition segment has the following wind flags that can be set using the checkbox.

Auto Find Path: Only available on transition segments – this will automatically stop the machine, perform a Find Path for the next segment, and start up again (unless the Hold flag is also set). The motion in the transition segment is essentially ignored.

Auto Hold: Automatically holds the machine at the segment boundary. The user will need to release the hold condition to continue.

Mandrel Offset: When set, the mandrel will not move to the zero degree location at the beginning of the segment. If set in the first segment of the chain, then the mandrelwill not rotate forward to the next zero location during the initial find path. Between segments, if not set the machine will stop and the mandrel will rotate forward. For this reason, it is a good idea to set this flag in all segments, especially after the first.

In general, if the user wants a file which will execute non-stop from start to finish, they should make sure that Auto Find Path and Auto Hold are cleared in all segments and the Mandrel Offset is set in every segment (it can be cleared in the first segment).

In addition to segment flags, this dialog box is also used to override the current entries fornumber of circuits in a given segment and also the names of each segment. Doubling the

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number of circuits effectively doubles the number of layers a particular segment will generate.

Transition Motion Files can combine any type of wind, although they tend to work best on winds which already mesh well (i.e. no major change in fiber angle, end points alreadyclosely aligned). In some cases, they are the only option – e.g. when chaining zero degreewinds. They directly incorporate their component motion files, meaning any already edited motion is left unchanged.

5.2 Transition Path Files

Transition by using Path files is typically more complex and powerful. In this case, the software ignores the data contained in the motion files to be chained. Instead, it goes and fetches path file data from .pth files with the same name and uses these as the basis for generating the chain file. It uses this path data to build a model of the mandrel, and, in turn, uses both of these to generate a transition fiber path, which connects the end of one program to the start of the next. Finally, it takes this resulting fiber path and generates machine motion in a similar manner to how motion is generated for wind files.In general, transition path files have a much better chance at combining diverse segments with stable transition regions – going from a low-angle bottle wind to a final outer hoop wind is relatively straightforward.

Because it works with path files and generates a transition path, this option requires that the .mmt files to be chained are accompanied with .pth files of the same name. This implies that even if the user is generating filtered motion, instead of chaining the filtered motion files, he/she should chain the original files (without the appended “flt”). Filtering can then be applied to the resulting motion.

Two parameters are set for this type of chain wind:

Transition Region Threshold: Establishes the frequency of points generated in the transition region in terms of linear fiber path. The user may need to try a few values for the software to accept the wind parameters.

Transition Region Rate: Establishes a limit similar to a wind angle to the transition region – defined as limiting the carriage speed vs. mandrel speed (i.e. number of carriage position units per revolution of the mandrel).

Once the user has entered all the files to be chained and set the above parameters, clicking on Calculate Chain will generate the new path and display the chain/transition feedback interface panel. At this point, a new path has been generated, meaning the user can generate 3-D visual simulation.

Finally, when satisfied, the user would click on Next. This brings up the Generate Motioninterface panel. Generating Motion has been discussed previously.

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5.3 Do Not Transition

As a final option, the user can have the software simply chain files together with no calculated intermediate motion. The process is similar to that for Transition Motion Files except no parameters are entered on the first screen. This motion option is typically used in the following two cases: either the existing motion matches up extremely well (e.g. various helical winds with only an angle variation) or the operator intends to stop the machine between layers, tie off the fiber and do a find path. In the latter case, the utility of the chain file is primarily simplifying the execution of multiple layers.

If the layers mesh well, the user could use similar segment flag settings as with other chain-wind types (i.e. only set the Mandrel Offset flag). Otherwise, flags should be set such that the machine holds at the end of each layer. Even though no motion is implied, due to software constraints, there will actually be a miniscule motion segment inserted (ofabout two degrees of mandrel rotation). This can cause a need for motion editing if an axis other than the mandrel is moving during the transition.

5.4 Chain File Tips and Troubleshooting

When generating path-based chain files, it is important to use “equivalent” mandrels for each segment. This is because the software uses path file coordinates to reconstruct a composite mandrel shape of all the different layers. For example, even slight differences in part diameter can result in highly erratic crossfeed behavior because the mandrel surface will consist of tightly spaced points with varying diameters resulting in a very jagged part surface. Some tips for obtaining a consistent mandrel are:

Always use the exact same bottle specifications for different layers (i.e. use the same bottle shape type, the same diameter, cylinder length, same dome width, etc.). The same applies to non-linear winds.

To overlap a circumferential wind on a non-linear wind, use the circumferential option of the non-linear wind.

To overlap a circumferential wind on a bottle, set the start and end coordinates appropriately. For example, if a ellipsoidal bottle has a left and right dome width of 5 inches and a cylinder length of 20 inches, the circumferential wind’s start andend coordinates need to lie within 5 and 25 inches.

This restriction only applies to path-based chain winds. The other modules do not attemptto reconstruct the mandrel shape.

If a particular segment / layer is to be repeated several times in sequence, it is usually a better idea to modify the number of circuits instead. This avoids generating so many transition regions and simplifies any additional editing. It also reduces the final file size.

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When connecting highly dissimilar segments, it is usually better to have their motion startat opposite ends of the part. For example, when chaining a low-angle bottle wind to a circumferential wrap, the user would typically start (and end) the bottle winds at one side of the mandrel and then begin the circumferential wind at the other. This makes it easier for the software to find a reasonably stable path. This left-right setting is typically made when selecting a path or when entering part parameters. See the individual chapters of thewind-types in question for more information. In rare cases, the opposite case may work better (i.e. both segments ending on the same end of the mandrel) so the user may want toexperiment with these settings.

6 Viewing and Editing Motion

Once the user has generated the motion to build a part, for further evaluation and editing -the motion can be opened in SimWind2 either as a graph or table.

To view and edit motion, the user opens the motion file using a typical File Open Dialog.This can be accessed by File > Open. The user then has to choose the .mmt, .chnextension to filter, locate and open the motion file. The default format is the graph. Theuser can switch to the table format with Motion > Table in the Main Menu.

When loading multi segment motion files - the first segment is displayed. The user canswitch segments by using the Segment Info tool bar menu button shown in Figure 31. Onclicking the menu button a new dialog window with a list of all the segments isdisplayed, see Figure 32. The user can navigate and highlight the segment he wants toinvestigate and edit and then click on the Load button. This will update the graph or thetable with the selected segment.

The user can also edit the circuit and flag information using the Segment dialog window.

The segment flags are discussed in 5.1.1.

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Figure 31: Segment info toolbar menu button.

NOTE: Editing motion should only be done after exhausting all possible iterations to obtain a stable fiber path by changing Wind and Generate Motion parameters.

Viewing and editing motion as a graph and table are discussed in Section 6.2 and Section6.6 respectively.

6.1 Overview of motion format

Before getting started on motion editing, it is important to understand how motion isconstructed in SimWind2.

6.1.1 Mandrel - The Timekeeper

All motion is tied to the mandrel, which represents a master timekeeper. The mandrel operates at a constant rate and all other axes coordinates are calculated to correspond to given positions of the mandrel axis. This becomes apparent when editing the motion file - the mandrel axis is generally a straight line which starts at 0 degrees and ends at however many degrees are required for one complete motion circuit.

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Figure 32: Segment information dialog.

6.1.2 Virtual Mandrel [VM]

The software uses an additional axis called the Virtual Mandrel or VM. This allows the mandrel motion to be edited. Before editing, the VM directly corresponds to the mandrel motion. In the various motion editing screens, the horizontal (X) axis corresponds to the VM while the vertical axis (Y) corresponds to the axis being edited.

If the mandrel axis is altered, it no longer corresponds directly to the VM, but is mapped to it - just like the other axes. In effect, the VM axis corresponds to time - with one modification i.e., the Rate Envelope (Section 6.1.3).

6.1.3 Rate Envelope

The rate envelope is used to globally scale the machine’s velocity across all axes. This rate envelope was introduced in order to enforce various limits on machine motion (for example, when generating constant fiber speed or maximum axis speed programs).

6.2 View and Edit Motion in Graph

Once the motion is loaded as a graph, the user should see a graph similar to the one inFigure 33.

The X-axis represents the virtual mandrel (VM) values, and the Y-axis represents the axispositions. In the middle region of the graph panel - the Velocity is displayed in Red and the Acceleration in Green. Velocity and Acceleration are calculated against the VM (e.g. velocity units are inches or mm per radian of VM motion). In general, the magnitude of velocity and acceleration is of limited use, but they allow user to quickly locate potential problem regions.

The graph also displays Major Tick marks of VM and position values along with their units on the X-axis and the Y-axis.

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For example: If a machine has a top mandrel speed of 150rpm, the rate envelope is a flat 100% and the mandrel has not yet been edited (i.e. it simply corresponds to the VM), then the mandrel will run at a constant 150rpm - and the other axes will track the mandrel as needed. If the rate envelope drops to 50% at some point in the circuit, then all axes would effectively run at 50% during that section - the mandrel would drop to 75rpm.

Figure 33:Carriage motion being displayed as a graph.

If the user wants to view all the segments in the motion graph, he can click on View All context menu item. This will update the graph with all the segments.

The VM and Position values at the current pointer location are displayed on right the of the status bar on the main window, see Figure 35.

6.2.1 Selecting Axis to Display

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Figure 34: View all segments

Figure 35: Status bar display of VM and position values at a pointer location.

The user can select which axis to display either by using the Motion menu (Figure 36) located on the Main menu, or the Graph context menu (Figure 37) which is accessed by the right-click of the mouse pointer anywhere on the graph panel.

Depending on the machine configuration, up to 6 axes plus the rate envelope are available to view. Each axis uses the same basic format except for the rate envelope, which does not have velocity or acceleration vectors. Also, functionality such as edits andzoom are not available for the Rate Envelope. It is easier to edit the Rate Envelope in the Motion Table. This is discussed in Section 6.6.1.

Figure 36: Motion Menu Figure 37: Graph Context Menu

6.3 Editing Motion in Graph

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Note: The graph is automatically scaled depending on the size of the Graph panel, which is in turn dependent on the size of the main window. This scaling takes place each time the user switches the axis or when the motion is reloaded.

Various tools exist to assist the user with editing a motion file - these are accessible through the Edit Motion Toolbar at the top of the main window (Figure 38) and/or by using the Graph context menu.

Figure 38: Edit motion tool bar items.

To edit a Motion file - the user can add and delete motion trajectory points. and change the interpolation for the axis. The user can also make changes that affect the entire motion of an axis by using transform tools. These tools are discussed in Section 6.5.3.

6.4 Zoom Tools

6.4.1 Zoom-in

Before getting into editing, the first step is to Zoom into the interested region. To do this, the user clicks on the Zoom-in toolbar menu button (Figure 39). The next step is to drag abox around a region of the graph for closer inspection. To do this, press and hold the left button in one corner of the region, then drag the mouse to move the pointer to the opposite corner of the region. As soon as the left button is let go, the graph is updated with the target region. The user has the ability to zoom in more than once without having to click on the Zoom-in button again.

Figure 39: Zoom-in toolbar button. Figure 40: Zoom-out toolbar button.

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NOTE: Editing tools to add and delete motion points are available when the graph is zoomed in.

Figure 41:Shows the region being selected for closer examination.

Figure 42: A closer look at the region.

6.4.2 Zoom-out

To revert to the original display, the user needs to click on the Zoom-out button (Figure 40). This reloads the axis in the graph.

6.5 Steps involved in Editing

Step 1: Open Motion file

Open the motion file as a graph and choose the axis (section 6.2.1) to be edited using the Motion menu or the Graph context menu. Focus on the region if necessary with the help of the zoom-in operation.

Step 2: Select the Operation - Add or Delete.

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Select add or delete motion trajectory points by clicking on the Add Points toolbar menu button (Figure 43) or the Delete Points button (Figure 44).

Figure 43: Add points. Figure 44: Delete points.

Step 3: Perform operation.

Add or delete the motion trajectory points. These operations are explained in detail in6.5.1 and 6.5.2.

Step 4: Check edits

The user can accept or reject edits by clicking on the Accept toolbar menu button (seeFigure 45) or the Reject button (see Figure 46 ). If motion is edited, the new data appears as a red dotted line superimposed on the original motion.

Figure 45: Accept edit toolbar menu button.

Figure 46: Reject toolbar menu button.

Step 5: Accept or Reject edits

If the new data appears acceptable, clicking on the Accept Edit toolbar menu button againwill finalize the change. Alternatively, the Reject Edit menu button will revert to the previous motion data. At this point, the graph has newly edited data - but not saved to the motion file yet.

Figure 47: Accept toolbar menubutton.

Figure 48: Reject toolbar menu button.

Step 6: Save to motion file or Reload file

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NOTE: The changes are NOT written to the motion file until Step 6 (see next step).

The final step is to write the new motion to a file. This is done by overwriting the existingfile with File > Save or by creating a new motion file using File > Save As in the Filemenu or the File context menu.

To reject all edits before a file was saved, the user can click on the Revert To Originaltoolbar menu button (Figure 49) to reload the motion from the motion file.

Figure 49: Revert to Original motion menu button.

6.5.1 Deleting Motion Points

To delete motion trajectory points, first select the Delete points operation and then drag a box around the region containing the motion trajectory points to be removed. To do this, press and hold the left button in one corner of the region, then drag the mouse to move the pointer to the opposite corner of the region, see Figure 50.

Let go of the mouse button. The user should now see the dotted red line representing the new motion with the motion points removed, Figure 51. If the user is happy with this, he can move on to the next step or repeat the step again by selecting a new region.

The user can now choose to accept or reject the edit into the motion object. As discussed before, the motion is not written to file yet, refer Section 6.3 to save changes to a motion file.

Figure 50: Shows the selection of the motion points.

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Figure 51: The dotted red line shows how the motion would look like with the selected motion points removed.

Figure 52: Shows the new motion on accepting the edits shown in the previous steps.

6.5.2 Adding Motion Points

To add motion trajectory points, first select the Add points operation and then place motion trajectory points on to the graph. To do this, move the mouse pointer to the location of the new motion point and press on the left mouse button. This should create a small red square representing the motion in that position, see Figure 53.

On accepting the new motion points with the Accept Edit menu button, the user should now see the dotted red line representing the new motion with the newly added motion points, Figure 54.

The user can now choose to accept or reject the edit into the motion object. As discussed before, the motion is not written to file yet, refer Section 6.3 to save changes to a motion file.

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Figure 53: Shows new motion points being added.

Figure 54: The dotted red line shows how the motion would look like with the newly added points.

Figure 55: Shows the new motion on accepting the edits shown in the previous steps.

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6.5.3 Transform Tools

Transform motion tools allow the user to adjust the entire motion of an axis. The transform tools are accessed using the graph context menu, see Figure 56. An axis can be mirrored, offset and scaled. These transforms are discussed in the following sections.

Along with axis scaling - the time axis can also be scaled.

Figure 56: Transform motion tools.

6.5.3.1 Mirror Axis

An axis can be mirrored - this results in mirroring the data horizontally (inverting the time axis). Clicking on Transform > Mirror Motion applies this transform.

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Note: Same results can be obtained through some combination of inverting the mandrel rotation, inverting the eye rotation and/or starting the layer on the right side of the mandrel.

Use CAUTION when mirroring - especially on the crossfeed and carriage, they generally need to be mirrored together.

A linear axis can be offset - which moves all axis positions in a particular direction. Clicking on Transform > Offset menu item generates another dialog box (see Figure 58). The user has to enter the offset for the axis and then click on Okay, this value is applied as an offset to all motion points and the motion graph is updated.

Figure 58: Axis offset dialog.

Figure 59: Shows the carriage motion in Figure 33 offset by the value shown in Figure 58.

Offsetting the machine can also be performed in Flexwind - but by using the Offset motion menu item, the change can be made permanent. Offsetting follows the conventional axis definitions (e.g. positive value for carriage offset would cause the program to move closer to the tailstock as shown in Figure 59).

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Figure 57: Shows the motion after mirror transform was applied. The original motion is seen in Figure 33.

6.5.3.2 Rescale Axis

An axis can be rescaled - which allows the user to set different end points for the axis. The resulting motion will be linearly interpolated to lie between the new end points.

Clicking on Transform > Rescale Axis menu item generates another dialog box (seeFigure 60) showing the Start value and the End value. The start value is the minimum value of the axis positions and the end value is the maximum value of the axis positions. The user can change the start and end values and click on Okay. The axis is rescaled and the motion graph is updated.

Figure 60: Rescale dialog.

Figure 61: Shows the rescaled axis with the values shown in Error: Reference source not found. The original motion is shown in Figure 33.

6.6 View and Edit Motion in Table

Once the motion is loaded as a table, the user should see a table similar to the one inFigure 62. The table gives the user very precise access to the motion of all axes at once.The table is arranged as columns containing cells. Each of these columns are discussed below.

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Note: An axis can be mirrored vertically by reversing maximum and minimum valuesin Start and End value.

VM / Indp (ds) Column: Virtual Mandrel column contains relative time entries expressed in seconds. Relative (or incremental) time is used to ease insertion of new data.Actual program execution time is established via this column, modified by a linearly interpolated rate envelope, this is further affected by the execution rate set by the machine operator control.

This column is somewhat difficult to directly edit. It is often easier to use graphical functions to insert new motion points on the axis of interest and then use the table to enterexact positions for those points. However, if the user needs to add fiber length at a particular location (i.e. additional mandrel rotation), then this usually requires new entries(or similar calculations) to be made in this column. For more on altering this column / inserting additional mandrel rotation, see Section 6.6.1.

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Note: Unlike the axis columns, each row of the time column requires an entry – this is fairly intuitive, since the software needs to know the time for each machine coordinate. Also, this column is used by the software to determine the end of the program – which is the first blank entry.

Axes Columns : The next columns represent the present axes. The cells indicate the machine coordinates at any given time point. The Mandrel, similar to time, uses relative (or incremental) coordinates to make editing and inserting new points easier. The remaining axes use absolute coordinates since their motion is bounded and cyclical. The units are degrees for rotary axes and either inches or millimeters for linear axes. To switch units, navigate to Units Menu on the Main Menu and select the unit type.

The user can navigate through the cells, searching for a particular region of the wind and then directly modify the contents of these columns. As with all motion editing, caution is advised. Also, while the mandrel can also be directly edited, this process is more complexthan for the other axes. Changing mandrel entries directly affects the fiber length of the part and can have a significant affect on the pattern and fiber stability. This issue is covered further in Section 6.6.1.

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Figure 62: Motion table

Rate Envelope Column: The rate envelope scales the time in the VM column. For example, if the rate envelope is at 20% and a time-column entry is 0.4, then the motion from the previous row to the given row would take 2 seconds (if the machine is running at 100%). The rate envelope itself is linearly interpolated from one entry to the next - gradually accelerating or decelerating all axes along the way.

6.6.1 Editing Motion via the Table

The following section describes how to modify a motion table. Note that doing this will significantly alter program behavior, but it can be quite useful to generate specific winds. Examples include hoops or other recurring patterns within a more complex wind such as a bottle, or local fiber build-ups at fixed carriage locations. These are often difficult or tedious to automatically generate and properly chain. Editing the motion file should always be done with care. It should generally be the last step in a programming process because if motion needs to be regenerated later, all editing is lost and needs to be repeated. Finally, if the resulting file (or segment) is still expected to form a closed pattern, then any inserted mandrel length needs to be chosen with care. Ensuring a particular pattern with pattern closure requires some detailed analysis of the mandrel's motion, but one simple case always maintains the original pattern - adding any number ofcomplete hoops (360 degrees).

Along with editing cells directly to modify the motion table, SimWind2 also offers context menu to modify by inserting rows, deleting rows and deleting sections of the motion table. The context menu can be accessed by first selecting a row or multiple rows and then by the right click of the mouse pointer.

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Note: Individual position cells can be left empty. Only the first row in each segment and the final row of the entire program requires entries for each present axis (as well as the rate envelope). The software will automatically apply the given interpolation method to generate intermediate points where these are left empty.

Figure 63: Edit Motion context menu with a newly added row.

Add Row: Inserts a row of empty cells for the user to edit at the current pointer location.

Delete Selected Rows: Deletes all the selected rows.

Delete Selected Area : Deletes all the axes and rate cell values except the VM cell values of the selected rows.

Before starting to edit the table, it is helpful to have plenty of entries in the mandrel column. Ideally, the table will have sequential mandrel entries on both sides of the insertion point like in Figure 63.

The first step is calculating the mandrel’s speed in deg/sec. To do this, divide the change in mandrel angle (entries in the Mandrel column) by the change in time (the VM column). Note that these are both incremental measures. For example, if the mandrel has no entry in the previous 3 rows, the user would need to sum the independent entries in these rows plus the row containing mandrel data and divide by this value.

With this information, the user can now insert some motion. It is often easiest to insert a few rows with the Edit Motion context menu, although existing entries can also be alteredto achieve the same effect. When inserting rows, simply enter mandrel values which sum to the desired additional rotation (e.g. 4 entries of 360 would add 4 hoops). In the VM column, enter the duration of each motion - generally keeping with the current speed, although gradual accelerations or decelerations are also possible.

Using the example figure, consider the second row. The mandrel is rotating 3.261247 degrees in 0.010871 sec or 300 deg/sec. So, if the user wished to enter 4 new rows of 360deg each, the independent time column would contain 1.2 seconds for each mandrel entry. This would maintain the same constant speed. If altering existing segments, the user should add any changes to the current entries in those segments – e.g. the mandrel entries in the figure would change from 3.2612476 deg to 15 deg and the time entries from 0.010871 to 0.05 sec.

Finally, once the mandrel motion has been inserted, all editing functions can be used to further refine, insert, smooth and otherwise alter the remaining (and even the mandrel) axis to obtain the desired result.

Once the edits are made, the user then accepts or rejects the edits by clicking on the Accept Edit button or the Reject Edit tool bar button.

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Figure 64: Accept Edit Figure 65: Reject Edit

As is always the case, the machine operator should be very cautious when executing any program for the first time, particularly edited ones.

7 Export/Import CSV

The Motion Table can be exported as a .csv. The .csv file can be opened in Microsoft Excel or a different spreadsheet utility. Once the file is opened in Excel, wide assortmentsof powerful spreadsheet features and tools are available to edit the motion. Once edited the motion can be imported back into the Motion Table.

7.1 Export Motion

Step 1Open the motion file - File > Open.

Step 2Click on the Motion > Export menu, this opens a typical File Save Dialog. The user can now enter a file name and save it.

Step 3Edit the motion, and save the file back as a .csv file. While saving, make sure the format of workbook remains unchanged.

7.2 Import Motion

Click on the Motion > Import menu, this opens a typical File Open Dialog. Navigate to the .csv and click on the Open button to load the motion contained in the .csv file.

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Note: Save and Close the .csv file in Excel before importing it back into SimWind2. This is because, sometimes Excel locks resources to the .csv file. This causes issues when trying to open the file in other software.

IMPORTNAT: Once the user is satisfied with the edits, the user then has to register the edits to the motion file with a File Save, which can be accessed File > Save or the File panel context menu.

Figure 66: Shows a simple motion .csv file opened in Excel.

7.3 Format of CSV

When the .csv file containing the motion is opened as a spreadsheet, the user will find theformat to be the same to the motion table in SimWind2. The .csv file also contains a header with information regarding the units used, various flags, circuits and interpolation values for the axes present.

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Note: It is advised the user only change the Name and Circuits in the header if needed, and leave the rest of the header as it is.

8 Visual Rendering

The user can visualize the 3D rendering of the mandrel profile and the fiber path before and after selecting the path pattern.

Before deciding on the path pattern for generating motion, the user can simulate different path options by using the Simulate button on the Pattern Selection dialog window shown in Figure 20.

The user can also render the mandrel definition and the fiber path using menu option View > View Simulation. SimWind2 at this point reads the mandrel definition (.mdf) and fiber path (.pth) files generated during the path selection to generate the rendering. If the.pth and the .mdf files are missing, SimWind2 brings up appropriate message indicating the missing files.

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Note: When rendering using the Simulate button - SimWind2 is NOT rendering using.mdf and .pth files, as these files at this point have not been created. The creation and writing of the .mdf and .pth files take place only after selecting the pattern using the Select Path button.

Figure 67: Simulation window.

The simulation window offers menu buttons for additional features.

The user, with the help of these menu buttons can Zoom in and out of the rendering scene, the user can rotate and have the rendering animate the rotation.

The user can also change format of the graphic by clicking on the settings button. This brings up a new dialog box shown in Figure 70.

Mandrel Surface points: This determines how many sample points the software should make during this revolution. The larger the number, the more circular the part cross-section becomes (e.g. a value of 4 would yield a square mandrel). Generally, the user can leave the original default of 90 unless their computer is particularly slow.

Augment Path: The fiber rendering algorithms use the fiber path points calculated during wind path generation. They then use straight lines to connect

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Figure 68: Simulation menu buttons.

Figure 69: Simulation settings menu button.

Figure 70: Simulation settings dialog window.

Note: All entries made in the settings dialog box have no effect on any other portion of the software or the part itself – they only affect how the part is rendered on the screen.

Note: The 3-D part model is calculated by taking a 2-D part outline and revolving it.

these (linear interpolation). In some cases, particularly with circumferential winds, there are significant gaps between points. This leads to coarse, blocky interpolation. Selecting “Augment Path Data (display only)” will generate many intermediate points using smooth interpolation methods. In many cases, the resulting display is more accurate. However, if the display is blocky on bottle or non-linear winds, this usually indicates too few path points – it is a better idea to use smaller dome / cylinder threshold values.

Fiber bandwidth and Circuits are self explanatory. As noted before, they only affect how the part is rendered and not the actual part itself.

Wire Frame: Enabling the option turns on the meshes used to render the mandreland the fiber.

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Figure 71: Rendering with Wire Frame option enabled and the circuit number changed from the original value to 4.

9 Motion Filtering

Motion filtering provides a powerful mathematical tool to automatically smooth out motion files by reducing noise and vibration on the machine, while winding complex parts.

To filter a motion file - first open the motion file and click on the Motion filter toolbar menu button (Figure 72). This brings up a Motion Filter Parameters dialog box (Error: Reference source not found). The user can change the parameters and click on Filter Motion button.

Figure 72: Filter toolbar menu button.

The Motion Filter Parameter dialog box provides the user with parameters to tweak and smooth generated motion. If a motion file is edited and resaved, the user may re-apply filtering.

The initial, displayed filter parameters are the machine defaults. Only the available machine axes are enabled.

Upon filtering, a Filtered motion file is generated. The filtered file has the same name as the unfiltered file, but with the letters flt appended. For example when a motion file called bottle.mmt is filtered, a filtered file called bottleflt.mmt is created.

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NOTE: A filtered file is not automatically created when generating a wind. The user has to first open the unfiltered file, examine motion of all the axes, edit them if necessary and then apply the filtering tool.

Only apply filtering tool to non-filtered motion files and NOT already filtered files.

Figure 73: Motion filter parameters dialog box.

9.1 Basic Filter Parameters

Velocity Limit: The maximum allowable speed for the given axis. In general, only the mandrel's velocity limit needs to be adjusted according to size of the mandrel. Based on the resulting filtered motion, other axes may be adjusted down or up to improve the result.

Allowable Over Speed Factor: Filtering will ensure that that no axis' speed exceeds this limit times the allowable Over Speed Factor. This Over Speed Factor is used during acceleration filtering to correct position errors - axes may momentarily exceed their speedlimit during such corrections, up to the Over Speed Factor. To enforce a hard limit, reduce the axes' limit by dividing by the Over Speed Factor (e.g. if a hard limit of 150rpmis desired and Over Speed Factor is set to 110%, then set the axis' limit to 150 / 1.1 or 136.36rpm). The Over Speed Factor itself does not normally require adjustment.

Motion will follow a path in which one axis is at its velocity bound at any given time and other axes' velocities are scaled accordingly. Currently, the filtering algorithms do not have provisions for constant fiber speed or constant mandrel velocity, although a master axis (e.g. constant mandrel velocity) can be simulated by setting the desired axis' speed limit sufficiently low and the remaining axes' speed (and possibly acceleration) limits

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extremely high. This effectively slaves all axes to the axis with the low speed limit.

Acceleration Limit: The maximum acceleration limits for each axis. In general, only the mandrel's acceleration limit needs to be adjusted according to the size of the mandrel. (more importantly, its rotational inertia). If machine errors occur during program execution or machine vibration is excessive, reducing this parameter will help. The carriage axis is also a good target for reduced vibrations. Finally, reducing acceleration limits can act as a rather limited, low-pass filter if a given axis’ trajectory is particularly noisy. Depending on the generated motion, acceleration limits may also be raised, particularly on low-mass axes such as eye rotation and yaw. Ideally, machine defaults arebased on continuous motor torque and drive settings. However, some configuration files are known to have excessively high or low values. The following can serve as a rough guideline:

Axis Light Load Medium Load Heavy LoadMandrel 150 rad/s2 50-100 rad/s2 10-20 rad/s2

Carriage 100 in/s2

2.5 m/s2100 inch/s2

2.5 m/s250 inch/s2

1.25 m/s2

Elevation 50 in/s2

1.25 m/s250 in/s2

1.25 m/s230 in/s2

0.75 m/s2

Crossfeed 150 in/s2

3.75 m/s2100 in/s2

2.5 m/s2100 in/s2

2.5 m/s2

Eye Yaw 200 rad/s2 200 rad/s2 200 rad/s2

Eye Rotation 250 rad/s2 250 rad/s2 250 rad/s2

Table 1: Approximate acceleration values for different scenarios. The scenarios are based on overall machine and mandrel size and should be adjusted for additional loads on individual axes (particularly the carriage). * - For heavy / high rotational inertia mandrels, use of constant mandrel speed is recommended

Using these levels as baselines, the acceleration levels may be raised or lowered based onmachine behavior.

Unlike velocity, acceleration limits are applied to each axis individually and do not generally affect other axes (an exception is at the segment boundaries of chain files). Such multi-axis enforcement is more complex and the resulting motion can be undesirable. Instead, during acceleration reduction, local position errors are permitted. After a local acceleration region has been filtered, the resulting position errors are then

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Caution: The code does not enforce any limits on the user's entries - users should verify that a given motion is feasible and safe by studying the motion graph. Users should check the graph to ensure that the peak velocity on each axis does not exceed the factory specified velocity limit for that axis by more than a few percent. Specifically, if an axis exceeds the velocity range of the drive circuitry, then excessive position error may result if the program is run near 100% (the drive will saturate).

filtered out by applying low-level maneuvers at the start and end of the region (these in turn can introduce small overspeed conditions).

Position Error Limit: This limit is the tolerable path deviation from an ideal fiber pay-out motion path. This error is required for acceleration filtering to operate well. Very low settings can result in very slow machine operation because upon exceeding a position error limit the approximation method will lower an axis' speed limit until acceleration andposition errors are within bounds. In general, raising acceleration limits will reduce position errors - since this allows the axis to better track the original trajectory (but then the point of filtering is to reduce such high level maneuvers).

Filament winding is more tolerant of position errors. On stable paths, fibers typically move small amounts on any path, which is not truly geodesic. Furthermore, the smoothness of the motion is also important since large accelerations can cause vibration of the fiber. Users may wish to experiment with various levels of position error limits to evaluate tradeoffs in terms of part throughput and ultimate fiber path accuracy.

Note that position errors are not random errors. Examining the motion graph will show how and where these errors occur - they are introduced in regions where axes experience high acceleration levels. The lowered, filtered acceleration causes position error during the maneuver and also generates residual position error at the end-points. The filtering algorithm adjusts the start and end point of this maneuver to minimize this residual error and applies low-level maneuvers to eliminate them.

While paths with significant position error often still generate stable fiber paths which arenearly identical to the original fiber path, users must be cautious in setting limits and evaluating the results.

Using a bottle wind as an example, if a crossfeed begins to plunge-in slightly earlier, it may cause the payout system to strike the mandrel. To compensate the user can do some combination of the following:

- reduce the tolerable error on the offending axes (which tends to slow down the program)

- when generating motion, increase the eye side clearance, eye top clearance, and/orpayout eye tooling offset

- consider using the Min. Internal Err.

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Caution: Position error represents a path deviation. Excessive position error - particularly on the carriage and crossfeed axes - can generate a motion file in which the payout system can strike the mandrel or other tooling. To avoid problems, users should first examine the actual generated path and check the magnitude and location of the position error. When running any program for the first time, operators should use a minimal feed rate, especially any time the crossfeed is active (e.g. the ends of bottles) and be prepared to stop the machine.

Some final notes on position errors:

- Position errors are non-cumulative - cycles on all axes still close properly and without any steps in velocity or acceleration. This also applies to segment boundaries on chained files.

- Users may note a constant position error on the mandrel in the filtered motion graph. This is due to the mandrel's unique property which forces the mandrel to start at a particular angle. If an acceleration is adjusted which wraps around from one cycle to the next, then a position error is introduced at the start of the segment. The entire trajectory is then shifted so it begins and ends at the correct mandrel angle. Note that in almost all cases, this constant error is safely ignored.

Figure 74 shows how acceleration filtering operates and introduces position errors. This is a fragment of a motion graph. The light blue line shows the original velocity profile. It experiences a high-level acceleration at around 1.4 seconds (the brown line). Filtering causes the maneuver to start earlier and at a lower acceleration level (the purple line). Theyellow line shows the resulting velocity profile. The algorithm attempts to minimize the resulting position error (blue-green line indicates magnitude) at the maneuver end-points. On this particular graph fragment, acceleration was reduced from a peak of about 10.1m/s^2 to 2.4m/s^2 and a peak position error of 1.6cm was introduced (note – scale ongraph is normalized).

Figure 74 – a graph showing acceleration filtering

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9.2 Additional Filter Parameters

Lower Acceleration: This first set of checkboxes allows the user to turn on an additionalapproximation algorithm which will attempt to further reduce the acceleration limit on a given axis until it either reaches 1/8 of its original level or the position error becomes excessive (a binary approximation algorithm is used). This can be very useful on the mandrel and carriage axis since these tend to have the greatest affect on machine vibration. If a motion profile consists of brief spikes in velocity, then this option is very effective, while it tends to have no affect on an axis which is already operating near its acceleration and velocity bounds over much of the trajectory. In such cases, if vibration isstill excessive, the user should reduce an axis’ acceleration limit (which will reduce the axis’ velocity limit until a compliant trajectory is found).

Min. Internal Error: The second set of checkboxes applies a different criteria during position error compensation stage of the acceleration filtering algorithm. Normally, the algorithm attempts to minimize the end-point errors introduced during acceleration filtering – these are the errors which must then be removed through further maneuvering. The algorithm does not evaluate the error levels encountered within the filtered (i.e. constant acceleration) region. If this box is checked, after establishing the filtered region, the algorithm will also determine the minimum and maximum position error encountered and adjust the start and end position to minimize these.

In general, this will result in additional position error compensation maneuvers because the end-point errors will increase. However, for some maneuvers, this trade-off can be useful. This is especially the case on the carriage (and sometimes the cross-feed) axis if these are generating peak position errors at the ends of a bottle (which often tend to reduce clearance) – setting this box can reduce the peak errors which can yield additional surface clearance. The following graphs show such an example:

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Figure 75: Shows two motion graphs indicating the effect of minimizing the internal position error of a high-acceleration region (Min. Internal Err. is turned on for the right graph)

The first graph shows a normal motion fragment, while in the second graph internal position error minimization it is turned on. The pink line represents the original position information while the purple line is the filtered position information. The blue-green line represents position error. As is clearly visible, the pink and purple lines cross each other more often when internal error minimization is turned on. Also, more residual error is introduced, so the axis is in error for a longer time, although this residual error is still quite small. However, the axis as a whole experiences significant improvement in peak position error. In this fragment, peak error is reduced from about 1.61cm to 1.16cm (note:the blue-green line is normalized and cannot be directly compared) – and for this particular trajectory as a whole, peak error was reduced from 1.92cm to 1.16cm and the crossfeed axis experienced a similar improvement from 0.68cm peak error to 0.36cm.

When applied to an appropriate trajectory, this algorithm tends to increase velocity and position overshoot at the end of the axis’ travel – in the example case, the position went from 0.08cm undershoot to 0.96cm overshoot and velocity went from 1.8% overspeed to 3.8% overspeed (in both cases, some overspeed was needed to eliminate position error, although neither case came close to the 10% default margin).

Soft Velocity Enforcement: Velocity enforcement takes place across all axes simultaneously – the violating axis causes the remaining axes to slow down. In this way, no position error is introduced. However, such enforcement can introduce significant acceleration spikes and velocity reductions on the other axes.

In a few limited cases, it may be desirable to disconnect the axes during speed enforcement – for example, at the ends of a bottle, the payout eye must do a rapid rotation of up to 180 degrees while the other axes experience little motion. Depending on the payout system, there may be a significant level of error tolerance in this motion. Turning Soft Vel. Enforce on will allow the given axis to attempt to correct for speed

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violations without slowing down the other axes. In general, this introduces significant position error, and is not appropriate for the major axes. However, if significant, momentary misalignment of the payout system (i.e. eye rotation / eye yaw) does not adversely affect fiber path stability or cause problems in the payout system, it can improve program throughput on some files. It is best suited to files where motion nearly stops while the payout system rotates.

If turned on, the user may select which portion of the overall position error may be “used up” during velocity enforcement (as opposed to acceleration enforcement). This value is unlikely to require adjustment. If velocity enforcement introduces a greater error, then themethod fails and the axis reverts to “normal” velocity enforcement (i.e. across all axes).

Reduce Mandrel Velocity Spike: Some mandrels (typically bottle winds) have a tendency to introduce velocity spikes on the mandrel axis due to rapid changes on the other axes. Such spikes do not significantly improve the program throughput and can be asource of significant machine vibration.

Setting this option on will cause the software to reduce the velocity limit of the mandrel by a certain factor (based on the entry in: % velocity step) and check to see how much this extends a program’s execution time. If the change is minimal (based on the entry in: less than % acceptable growth per), then the procedure continues until the growth in time is too large. This is the only algorithm which is turned on by default. It rarely needs to be turned off unless there is some compelling reason to squeeze every last fraction of asecond out of execution time.

9.3 Advanced Filter Parameters

These options adjust various parameters which affect the internal operation of the filtering algorithms. They generally do not require user adjustment, although they may improve performance in some cases. They fall into two categories – the first three parameters affect the oversampling algorithm while the next seven affect the acceleration filtering algorithm. Of these, the user will probably find the first set more useful.

Some caution is advised when adjusting these parameters. If any set of parameters cause problems, click on Restore Defaults to return to a stable state.

The first three parameters establish how the oversampling algorithm operates. The first step in filtering is to oversample the original trajectory. This gives filtering finer control and is especially important for simple paths such as helixes where the original trajectory consists of very few points. The parameters are as follows:

Max Evaluation Pts: This establishes the maximum number of trajectory evaluation points to use when filtering. Most modern computers can handle quite a large number of points for calculation. However, there are limits to how many points can be processed by Omniwind or Compositrak – see note below. On simpler files, this threshold is rarely reached, although with large files (and especially chained files), it can begin to lower the

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oversampling factor. Note that regardless of the number, the oversampling algorithm will never eliminate original points. In other cases, it will reduce the oversampling factor suchthat:

Original Points * Oversampling Factor < Maximum Evaluation Points

Oversample Factor: The original number of trajectory points is multiplied by this factor and new points are generated at equal intervals between the original points. If the trajectory has 3 points at t=1, 2, and 4 seconds and the oversample factor is set to 4, then the resulting trajectory will have points at: 1, 1.25, 1.5, 1.75, 2, 2.5, 3, 3.5, and 4. Information for these new points is interpolated from the original data. The default value is 10, which is reasonable in many cases. If a trajectory has a very limited number of points and the resulting filtered trajectory shows significant overshoot at transitions, then raising this value may improve results. Lowering this value will improve execution speed. Finally, if a trajectory is noisy (the acceleration axis has regions with very frequentand abrupt changes in acceleration which looks like noise on an oscilloscope), then this value should be set to 1 – oversampling will often generate even wilder oscillations in such cases.

Pruning min dt: After filtering is complete, the algorithm will prune oversampled points.Points closer than this threshold (in seconds) are pruned (deleted) such that the final set of points will have an average separation of this value. Original points are never pruned. Setting this value very low (e.g. 0.0001) will effectively turn off pruning.

A note on file sizes: The oversample factor greatly influences how many points are in thefinal file. Due to the integral nature of the oversample factor and pruning (see below) the final number of points in the filtered .mmt file is generally less than the number entered atMax Evaluation Pts. The actual number of points in the file can be determined from the motion graph, if the file is too large and the operating system seems to spend too much resources on handling it and is slow - the user may adjust the values in this dialog box. If the original data was already too large, the user may need to reduce the path thresholds which generated the original data: Cylinder Section Threshold and Dome Section Threshold are used for bottle winds and non-linear winds, and Path File Threshold for helixes.

The final seven parameters control how the acceleration filtering algorithm works. The algorithm consists of two parts – first scanning the trajectory for larger trends and evaluating and adjusting these. Then rescanning both these regions and the entire trajectory with a small window, looking for local acceleration violations.

The first part scans for acceleration regions based on moving pointers along the trajectoryand checking if certain conditions are met. The pointers track points of minimum and maximum velocity for a particular acceleration region. As long as a set of conditions is met, one pointer is dragged along until a threshold condition is met. If this threshold is not attained and the general trajectory trend changes (e.g. acceleration changes to deceleration), then the pointers are reset and the process continues. Once this threshold is

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attained, a region is considered to exist – it will continue to grow until another set of terminating conditions is met.

Once all regions are established, the region with the greatest velocity change is checked for acceleration violation. If found, the region will continue to grow until its starting and ending velocities divided by its duration is below the acceleration threshold – then a straight-line acceleration is applied between these points. The growth of the region is set-up to minimize error at its endpoints (unless the Min Internal Error checkbox for the given axis is set), and a compensating maneuver at low acceleration and velocity levels issuperimposed to eliminate this residual error.

The second type of scan passes a window over the trajectory. The algorithm verifies that the acceleration within this window is below the given threshold. If so, the window continues moving the length of the trajectory. Otherwise, the local region is adjusted in a similar manner as described above.

The following parameters affect this process:

Minimum Trajectory dv: This establishes the minimum change in speed (dv) over an entire trajectory before any acceleration enforcement occurs. This value is given as a factor of the axis’ speed limit. The value prevents trajectories with zero or near-zero speed change from causing problems during enforcement due to floating point issues. Trajectories with such minimal dv's on a particular axis often require no filtering even if they have significant acceleration due to noise. The default setting of 0.02 rarely requires adjustment, although if a particular trajectory has little dv but unacceptable noise, the value can be adjusted downward which may trigger acceleration enforcement.

dv Threshold: This establishes the threshold at which an acceleration trend is established.This is given as a factor of the total velocity change in the trajectory (i.e. maximum minus minimum speed). An acceleration/deceleration trend must cover at least this magnitude velocity change before being considered a region.

dv Turnaround: Once a region is established, this value affects one of the two terminating criteria. If acceleration changes polarity and the change in velocity exceeds this magnitude (defined as a factor of the total velocity change in the trajectory), then the region is fixed at its current start and end points.

Acceleration Hysteresis: This parameter has two functions – before a region is established, it establishes a minimum acceleration rate between start and end points. If this rate isn’t met, the region collapses. Once the region is established, its function is reversed – this minimum acceleration rate must be met between end point and the new evaluation point, otherwise the region won’t grow. It is defined as a factor of the axis’ acceleration limit.

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Min Shoulder: This parameter establishes the second condition for terminating an acceleration region – the width of its shoulder: if a velocity plateaus (i.e. it cannot grow due to the hysteresis defined above), and this plateau exceeds the duration of the region times this factor, then the region is fixed. For example, if an acceleration region has a duration of 0.3 seconds and Min Shoulder is 0.2, then the region would be fixed if its shoulder exceeds 0.06 seconds (assuming the turnaround condition didn’t kick in prior to this).

Local dv Threshold: the equivalent to dv Threshold for the windowing acceleration algorithm. This combined with the acceleration limit determines the minimum width (in seconds) of the scanning window. This scanning window then slides along the trajectory and if the average acceleration within any given scan exceeds the limit, then the region is again expanded and acceleration reduced in the same manner as described in the introduction above.

In general, dv Threshold, dv Turnaround, Accel Hysteresis, and Local dv Threshold are adjusted in tandem, because they closely interact. Reducing them all makes the acceleration filtering algorithm more sensitive to minor velocity changes, while large values require larger changes before filtering kicks in (which can be more effective at establishing trends on noisy trajectories – in some cases, it can be better to use large values for all of these except Local dv Threshold which is left small to filter noise).

Accel Region Growth: Acceleration regions grow in order to reduce the acceleration level within them. Once this level is acceptable, this parameter establishes if they can grow further in order to reduce residual error (the remaining position error at the endpoints). The algorithm will check the resulting residual error if the region grows at either extremity by one sample. If this error is less than the current residual error, growth continues until the duration of these added segments exceeds this factor of the initial region’s duration. For example, if an acceleration region requires 0.5 seconds to obtain anacceptable acceleration level, and Accel Region Growth is set to 0.2, then it may grow upto 0.1sec more as long as such growth continues to reduce residual position error (note that this does not ensure that peak position error within the region is also minimized – theaffect on it is indeterminate).

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