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Unread 15-08-2012, 17:07
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Levansic Levansic is offline
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AKA: Len Evansic
FRC #0585 (Cyber Penguins)
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Re: Encoder with CAN for Drive Train

Do you have a gyro setup and connected to the holonomic drive?

The default for the cartesian holonomic drive is a field-centric control, meaning a forward command would move the robot away from the driver, no matter which way the robot actually faced. It sounds like you may have a drifted gyro accumulator, which makes the vi interpret your side to side commands as a diagonal movement, relative to the local coordinates of the robot.

Our robot could rotate much faster than our gyro could handle. This would "upset" the gyro accumulator, and cause the robot to move in un-intended directions. The gyro vi may need to be sent a reset signal.

On the drive wheel encoders for mechanum wheels and CAN Jaguars, good luck. We attempted to do that this year, but the onboard PID in the Jaguars was just too fragile. Maybe that's not the correct word, but is probably the most euphemistic I can muster today. Probably the best example we hit this year to illustrate the difference between theory and practice. In our case, no matter how much we practiced, we could not make it match the perfect theory. In the end, we just used %VBus, and attempted to scale our inputs so that we wouldn't approach the rotation speeds that upset our gyro.

-- Len

Last edited by Levansic : 15-08-2012 at 17:19.
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