03-cad input devices

8/12/2019 03-CAD Input Devices

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3. CAD Input Devices

Yrd.Doç.Dr. Ahmet Zafer Şenalp

e-mail: [email protected]

Makine Mühendisliği Bölümü

Gebze Yüksek Teknoloji Enstitüsü

ME 521

Computer Aided Design

mailto:[email protected]

mailto:[email protected]



Hardware of a CAD System

Computer System

Mainframe Computer and Graphics Terminals Powerful Inconvenient High cost

Turn-key CAD System Dedicated computer systems for CAD applications, consisting of a super-mini computer and several design work stations. Following the "central control concept" Inconvenient and not powerful enough for complex 3D modeling.

Workstations & High-End Personal Computers Supporting multiple tasks Supporting network and file-sharing – convenient Low costs Present and trend

Dr. Ahmet Zafer ŞenalpME 521

2GYTE- Makine Mühendisliği Bölümü




Hardware of a CAD System

Input/Output Devices

Graphical Input

Alpha Numeric Input

Graphical Output

Alpha Numeric Output

Computer(CAD Workstation,

Computer Terminal,Micro computer)






Conventional keyboards are text only devices. Keyboards are the essential and basic input devices for allcomputer applications. They are typically employed to create & edit programs or to perform word processingfunctions.A typical keyboard is shown in the above figure. It is divided into four different areas

• The first area " (A) " is for normal typewriting when entering text strings.• The second one " (B) " is the function key area for simplified handling of common operations.• The third area " (C) " is composed by seperate cursor and control keys. This area presents several different

configurations depending on the supplier of the keyboard, including arrows, thumbwheels etc• The fourth area " (D) " is the numeric keyboard for fast numerical digit input.

Working principals of keyboards are simple. A keyboard has typically two registers whose contents can beread by the computer, one to set a status bit when a key has been struck the other to identify the key by itscharacter code.The value of the status bit is monitored in a continuous repetitive manner. When the user hitsa key, the status bit is set and application program is consequently interrupted to clear the status bit,followed by reading the corresponding code of the key character. The loop is repeated every time the user

strikes a key.




http://upload.wikimedia.org/wikipedia/commons/3/3c/Cherry_keyboard_105_keys.jpg



Tablet is a computer input device that allows one to hand-draw images and graphics, similar tothe way one draws images with a pencil and paper. These tablets may also be used to capturedata or handwritten signatures. It can also be used to trace an image from a piece of paperwhich is taped or otherwise secured to the surface. Capturing data in this way, either bytracing or entering the corners of linear poly-lines or shapes is called digitizing.

A graphics tablet (also called pen pad or digitizer) consists of a flat surface upon which the usermay "draw" or trace an image using an attached stylus , a pen-like drawing apparatus. Theimage generally does not appear on the tablet itself but, rather, is displayed on the computermonitor . Some tablets however, come as a functioning secondary computer screen that youcan interact with directly using the stylus.

Some tablets are intended as a general replacement for a mouse as the primary pointing andnavigation device for desktop computers.




http://en.wikipedia.org/wiki/Stylus_(computing)

http://en.wikipedia.org/wiki/Computer_display


http://en.wikipedia.org/wiki/Stylus_(computing)






http://upload.wikimedia.org/wikipedia/commons/5/57/Tablet_gerber.jpg

http://upload.wikimedia.org/wikipedia/commons/1/16/Wacom_Pen-tablet.jpg



In computing , a mouse is a pointing device that functionsby detecting two-dimensional motion relative to itssupporting surface. Physically, a mouse consists of anobject held under one of the user's hands, with one ormore buttons. It sometimes features other elements, suchas "wheels", which allow the user to perform varioussystem-dependent operations, or extra buttons or featuresthat can add more control or dimensional input. Themouse's motion typically translates into the motion of acursor on a display , which allows for fine control of agraphical user interface .

First mousse of the world (1952)

The first computer mouse,Douglas Engelbart , (1963)




http://en.wikipedia.org/wiki/Computing

http://en.wikipedia.org/wiki/Pointing_device

http://en.wikipedia.org/wiki/Two-dimensional

http://en.wikipedia.org/wiki/Cursor_(computing)


http://en.wikipedia.org/wiki/Graphical_user_interface

http://en.wikipedia.org/wiki/Douglas_Engelbart

http://en.wikipedia.org/wiki/Douglas_Engelbart

http://upload.wikimedia.org/wikipedia/en/2/2d/Firstmouseunderside.jpg

http://upload.wikimedia.org/wikipedia/en/a/ab/DATAR_trackball.jpg







http://en.wikipedia.org/wiki/Cursor_(computing)







http://en.wikipedia.org/wiki/Computing



Cable MouseIn early times of computers mouse work by connecting to serial port. Recently this connection

is adopted to PS/2 port. Today, most cable mouse connects to the USB port of a computermouse. In addition, by means of various adapters, USB ports can be converted to PS / 2 orvice versa.

Cordless MouseInfrared mouse : This mouse uses an infrared communication with the computer. System isconnected to computer’s serial, PS/2 or USB port, and mouse connects to the system bymeans of infrared rays. If an object is present between the mouse and the system mousemovements won’t be detected. Today this type of mouse is no longer available in the market.

Radio wave mouse: Different from infrared mouse this mouse use radio wave signals forcommunication. Coverage areas is generally measured in tens of meters.Bluetooth mouse : This mouse use Bluetooth cordless technology for communication. Hasadvantages compared to above two types: Can be used wiyh every device as uses a standardprotocol (PC, Apple and even Pocket PC)






Types according to motion detection methods:Mechanical miceMechanical mice detects motion by means of a ball which can rotate by the mousemovement. This ball is coated by rubber and inside core is metal. As dust can coverthe movement ball by passing time maintenance should be performed.






LEDed Optical MiceThese types of mice enable motion by reflection of the LED emitted. Top versionmodels has 1000-2000 dpi resolution.






Laser Optical MiceThese types of mice enable motion by light emitted by laser light source. Bu türAppropriate choice for those desire high resolution. Resolution can be 3000 dpiand more. If mice are categorized according to motion detection, most expensiveis the laser optical mouse.






A trackball is a device which is very similar to a mouse. Itconsists of an “upside -down” mouse, in which the ball on thebottom of the mouse has been turned up to the top. As the ball isrolled by the hand of user it moves and the cursor on the screen. Itcontrols the position of the cursor on the screen with the directionof rotation controlling the direction of cursor movement and thedistance the cursor travels controlled by the number of revolutions

of the ball. Also some functional buttons can be added to thetrackball similar to mouse.

In CAD applications large balled models are preferred for betterprecision. Before the invention of touchpad the usage of trackballwas common in laptop computers.

With the end of 1990’s with the invention of scroll wheel that isused in mice the usage of trackball is decreased.

Still used in cartography and similar applications.

The world's first trackballinvented by Tom Cranston, (1952 )

Logitech trackman




http://upload.wikimedia.org/wikipedia/en/a/ab/DATAR_trackball.jpg

http://upload.wikimedia.org/wikipedia/commons/6/68/Logitech-trackball.jpg



A Lightpen is an input device which allows interactionwith a display from a computer screen.The lightpens can be used to input data as well as to

draw as shown in the figure. The idea behind the lightpenis the familiarity of an ordinary writing. It is a direct andnatural form of input.

A light pen can work with any CRT-based display, but notwith LCD screens.

A light pen is fairly simple to implement. A light pen worksby sensing the sudden small change in brightness of a pointon the screen when the electron gun refreshes that spot. Bynoting exactly where the scanning has reached at thatmoment, the X,Y position of the pen can be resolved.




http://en.wikipedia.org/wiki/Liquid_crystal_display

http://en.wikipedia.org/wiki/Electron_gun

http://en.wikipedia.org/wiki/Electron_gun

http://en.wikipedia.org/wiki/Liquid_crystal_display



Even invented in 1952 became popular in 1980 ’s.

First

Light pen




http://en.wikipedia.org/wiki/Image:Handyusbpenlight.JPG

http://en.wikipedia.org/wiki/Image:Penlight.JPG



A touchpad (also trackpad ) is a pointing device consisting of specialized surfacethat can translate the motion and position of a user's fingers to a relative positionon screen. They are a common feature of laptop computers and also used as asubstitute for a computer mouse where desk space is scarce. Touchpads vary insize but are rarely made larger than 40 square centimeters

Touch pads consist of single plastic mylarmembrane silkscreened with a silverconductive grid and two resistive strips andworks in a similar way with touch screensexcept the fact that it works on a flatpad. When a key is pressed, two electricalresistances are reflected between a commonline and the x and y output lines.





http://en.wikipedia.org/wiki/Mouse_(computing)

http://en.wikipedia.org/wiki/Desk

http://en.wikipedia.org/wiki/Centimetre

http://upload.wikimedia.org/wikipedia/commons/b/b6/Touchpad.jpg

http://en.wikipedia.org/wiki/Centimetre

http://en.wikipedia.org/wiki/Desk

http://en.wikipedia.org/wiki/Mouse_(computing)




Windows 7 supports touchscreen usage






Buttons and function switches are either toggle or push-button switches. They may

be either continuously closed, continuously open, or momentary-contact switches. Themost common convenient type of function switch incorporates both capabilities. Softwarecontrolled lights indicating which switches or buttons are active are usually provided.Buttons and switches are frequently incorporated into other devices. Switches make theon/off settings for input or mode of operations.






Clasical Joystick: Literally only 1 or 2 button +

direction, functions as a control tool




http://upload.wikimedia.org/wikipedia/commons/b/b8/ControlSurfaces.gif

http://en.wikipedia.org/wiki/Image:Aptch.gif

http://en.wikipedia.org/wiki/Image:Aileron_roll.gif

http://upload.wikimedia.org/wikipedia/commons/1/10/Joystick.jpg



Input output functions: In old times control devices only reflectthe choice of the player to the game but by improvingtechnology joysticks are changed and joysticks that response tosense are developed. These respond according to the

movement they sense and generally vibration property ispresented by game devices such as PlayStation (dual shock)Example: A crash in a car race is responded by the vibration ofthe joystick.

Second Generation JoystickSecond generation joysticks have more than two buttons and haveperfect ergonomic structure, the routing function is analog and detectsall kinds of precise orientation and most important is that it is a controldevice with input output function.

analog controlled nintendo; first 64 then game cube applied




http://upload.wikimedia.org/wikipedia/commons/d/dd/PlayStation.jpg

http://en.wikipedia.org/wiki/Image:Joyopis.svg



The best example to the last generation joysticks: Nintendo wii control device

Cordless controlInput output functionSensing function: Sensing function enables the player’s the movements to besensed and converted to the game.Example: In a tennis play the movement of player’s hand is simulated as amovement of tennis racket




http://upload.wikimedia.org/wikipedia/commons/b/bc/Wii_Remote_Image.jpg



Nintendo wii






3D Data Acquisition Systems

2D Image: (for each pixel: X and Y coordinates and light intensity).The intensity could be gray (8 bits: 0 – 255) or color RGB (24 bits). 3D Range Image/Data from Range Sensing Devices and 3D Camera –data points defined by their x, y, z coordinates (cloud point data).

• Mechanical probe (measurement and scanning)• Laser scanning

Triangulation-based range sensing devices Time-of-flight based range sensing devices

Machine vision based CAD model generation for:• reverse engineering• machine vision and intelligent robot• vehicle size measurement and traffic monitoring• scanning of 3D object, human body, and art work






Automotive Design andCAD Model Generation

Scanning of Clay Model toObtain Surface Data

Design Details Using CAD System






Full Size Foam ModelMachined Using a 5-Axis CNC Millfrom 3D CAD Model






Scanners withMechanical Probe






CAD Modeling Basedon a 3-D Vision System

• 3D Range Sensors (3D Cameras): 3D Cloud Data Points – Triangulation-based: visible laser light,short range, accurate – Time-of-flight-based: laser light & micro wave, long range, less accurate

• Processing of 3D Range Data – 3D Cloud Data Points Cross-section-based CAD Model – Generation of a Complete Description for Objects and Workspace –

Sensor Fusion

• Forming a Surface Model and Carrying out Reverse Engineering – Cross-section -based CAD Model Surface Model CNC Machining;

RP; etc.






Multiple View Fusionand Model Integration

Dr. Ahmet Zafer ŞenalpME 521 34GYTE- Makine Mühendisliği Bölümü




Global Model Generation withMultiple View Fusion





Automated Vehicle DimensionMeasurement System for Commercial andOversize Vehicles

Implemented at BC Ferries Terminal

• Real -time Vehicle Dimension Measurement• Complex Vehicle Shapes

• Dimensions Measured at Speeds up to 120 km/hr

• Adverse Weather Conditions • Height and Width Accuracy: 15 cm • Length Accuracy: 30 cm





Automated Real-time Dimension Measurement ofMoving Vehicles Using Infrared LaserRangefinders





Automated Real-time Dimension Measurementof Moving Vehicles Using Infrared LaserRangefinders





Reverse Engineering and Automated CNC ToolPath Generation for Efficient and High QualitySculptured Part Machining

Geometric Modeling Based on 3D Scanning• Challenges:

– Accuracy/Lighting/Range (Selecting Right 3D Sensing Tech) – Occlusion (Obstruction)/Multiple View Fusion – Multiple Level Modeling: Cloud Data Points/Crosssections/

Surfaces/Solid• Applications: – Reverse Engineering (e.g. Face Mask) – Size Measurement (e.g. Moving Vehicle) – Object Recognition (e.g. Moving Vehicle) – 3D Log CAD Model Generation – 3D Sculpture Documentation – Shoe Making – Character Modeling in Movies/Computer Games


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