[Ether]

Originally Posted by EthanMiller

When I try to have the robot go sideways (Namely, JoyX=-128, JoyY=0), it sort of drives along an arc with a central point about 10 feet in front of the robot, as if the back wheel were going too fast.

Buchanan addressed this in an earlier post in this thread:

Originally Posted by buchanan

It will be surprisingly difficult to make the machine drive in a straight line, especially in directions other than the three where two wheels are turning the same speed and the third is stopped. The problem is that the beautiful theoretical math only works as expected with beautiful theoretical hardware. In particular, the math solves for wheel speeds, and unless you have a good wheel/motor regulation arrangement, what you're actually setting is motor drive (e.g. PWM) level. How this translates to wheel speed depends on the voltage/speed linearity of the motor and even more on the load. While this problem in principle affects other drive systems, it's worse on 3-wheel omni because you're almost always at different speed/load points for each wheel. We dealt with it using gyro feedback. Another approach would be closed-loop PID on each wheel so you really do get the wheel speeds your program asks for.