Mecanum Drift/Shift

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During autonomous testing, we noticed that the robot is drifting during Mecanum 
(left-right motion).

1) When driving straight right, the robot's right rear moves farther than the 
right front, so robot is at an angle.
When driving straight left, the robot's right rear moves farther than the right 
front, so robot is at an angle.

2) When transitioning from "drive straight back" to "drive right", the robot 
appears to jerk a bit, causing an initial rotation to be introduced.

These two behaviors compounded are causing significant drift in the autonomous 
software.

Analysis:

1) Review of the feedback from the encoders and the motors amps:

- All encoders (and thus the wheels) are moving at the same speed.
- The front motors are being driven at a higher amperage than the rear.

This suggests the front wheels are slipping, likely due to uneven weight 
distribution.

2) We have no analysis yet of the cause of the "jerk" at the transition from 
driving backwards to driving right.  Attempts to add a "wait" were no 
successful, but this appears to have been a coding error.

Original issue reported on code.google.com by scottlib...@gmail.com on 9 Mar 2012 at 5:53

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See picture for a suggestion on a modified autonomous path.

Original comment by kttn...@gmail.com on 10 Mar 2012 at 6:57

Attachments:

• ModifiedAutonomous.png

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Original comment by scottlib...@gmail.com on 14 Feb 2013 at 2:05

• Changed state: WontFix