Difference between revisions of "Twitch"

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==Twitch or Linkage Drive==
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==Twitch or Biaxial Drive==
  
FRC 1565 Think Tank Tech in Cambridge, Ontario created a linkage drive in 2007/2008.  The intial video's showed good mobility and speed.  This drive was one of the canidate drives to prototype.  
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FRC 1565 Think Tank Tech in Cambridge, Ontario created a biaxial drive (which they called "Twitch") for the 2008 (Overdrive) seasonVideos showed good mobility and speed (albeit using omni wheels).  This drive was one of the canidate drives to prototype.  
  
The drawings below show our interpretation of the drive setup.  
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The drawings below show our hypothetical chassis design basen on "Twitch" principles.  
  
 
<gallery widths=360 heights=220>
 
<gallery widths=360 heights=220>
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File:Twitch dwg y.jpg|Twitch - y drive
 
File:Twitch dwg y.jpg|Twitch - y drive
 
</gallery>
 
</gallery>
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Some principle points:
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* The design employed 6" KitBOT wheels.
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* Each wheel is independently driven by a CIM motor with a Bainbots 2-stage 12:1 reduction planetary gearbox.
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* (4) wheel independent suspension is provided
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* Chassis weight (as shown above) is 42.4 lb
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* Drive orientation is changed pheumatically, so the robot requires a pneumatic system with compressor & storage
  
 
== VEX Prototype ==
 
== VEX Prototype ==
In the summer of 2008 we built a prototype version of the linkage drive.  Each wheel had a direct drive  motor.  The twitch action was performed by rack/pinion gear set up.  It took about five second to do a full cycle.  The software was set up to be arcade drive on the right joystick, the left joystick controlled the twitch function.  The software allowed the driver to pick the "virtual" front of the robot.
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In the summer of 2008 we built a ½-scale prototype version of the linkage drive.  Each wheel had a direct drive  motor.  The twitch action was performed by rack/pinion gear set up (in lieu of pneumatic cylinder).  It took about five second to do a full cycle.  The software was set up to be arcade drive on the right joystick, the left joystick controlled the twitch function.  The software allowed the driver to pick the "virtual" front of the robot.
  
 
In the pictures below you can see the cycle take place.  
 
In the pictures below you can see the cycle take place.  
  
 
<gallery widths=200 heights=300>
 
<gallery widths=200 heights=300>
File:Twitch VEX 2008 1.jpg|Twitch wheels in N/S position
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File:Twitch VEX 2008 1.jpg|Twitch wheels in N/S (x) position
 
File:Twitch VEX 2008 2.jpg|Wheels 1/2 through the travel
 
File:Twitch VEX 2008 2.jpg|Wheels 1/2 through the travel
File:Twitch VEX 2008 3.jpg|Twitch wheels in E/W position
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File:Twitch VEX 2008 3.jpg|Twitch wheels in E/W (y) position
 
</gallery>
 
</gallery>
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The capability to pick any of the (4) robot sides as the front was viewed as a very positive feature.  Always drive forward.  If we implemented this on FRC-scale, we would use different colored bumpers for each side, and use the same colors on the user interface for intuitive control.
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In testing the prototype, we learned that it maneuvered well in the y-orientation, but poorly in the x-orientation.
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 +
Despite x-orientation steering problems, the robot is very agile.

Revision as of 12:08, 14 June 2009

Twitch or Biaxial Drive

FRC 1565 Think Tank Tech in Cambridge, Ontario created a biaxial drive (which they called "Twitch") for the 2008 (Overdrive) season. Videos showed good mobility and speed (albeit using omni wheels). This drive was one of the canidate drives to prototype.

The drawings below show our hypothetical chassis design basen on "Twitch" principles.

Some principle points:

  • The design employed 6" KitBOT wheels.
  • Each wheel is independently driven by a CIM motor with a Bainbots 2-stage 12:1 reduction planetary gearbox.
  • (4) wheel independent suspension is provided
  • Chassis weight (as shown above) is 42.4 lb
  • Drive orientation is changed pheumatically, so the robot requires a pneumatic system with compressor & storage

VEX Prototype

In the summer of 2008 we built a ½-scale prototype version of the linkage drive. Each wheel had a direct drive motor. The twitch action was performed by rack/pinion gear set up (in lieu of pneumatic cylinder). It took about five second to do a full cycle. The software was set up to be arcade drive on the right joystick, the left joystick controlled the twitch function. The software allowed the driver to pick the "virtual" front of the robot.

In the pictures below you can see the cycle take place.

The capability to pick any of the (4) robot sides as the front was viewed as a very positive feature. Always drive forward. If we implemented this on FRC-scale, we would use different colored bumpers for each side, and use the same colors on the user interface for intuitive control.

In testing the prototype, we learned that it maneuvered well in the y-orientation, but poorly in the x-orientation.

Despite x-orientation steering problems, the robot is very agile.