Holonomic drive weirdness

[Levansic]

We've used holonomic drive in several previous robots, but this weekend we saw something that we had not previously seen. Unfortunately, I don't have captures of the code, but we opened up a four-motor drive reference, and passed it to an unmodified WPI cartesian holonomic drive vi. We used X, Y, and Z axes for x and y translation and rotation respectively. We did not hook up a gyro, as we were only looking to use robot-specific rather than field-specific control.

Once the motor directions were properly set, we could correctly rotate left or right. Pushing the stick forward (Y+) gave the expected motor rotations to drive that direction. Pulling the stick backward (Y-) caused the robot to rotate - all wheels turning the same direction, rather than two clockwise and two counter clockwise.

Has anyone else seen this?

Our next moves are to deadband the three axes of the joystick, and to assemble our own holonomic drive vi.