Jaguar Speed Control Only Reaches 50% of Setpoint

[wmarshall]

I'm in the process of tuning the Speed PID loop on my team's Jaguars, and I'm having a similar issue. Using BDC-COMM to set the PID values, I can increase P until I get to just under my setpoint, but when the loop actually hits the setpoint, the Jags start freaking out and flipping the motor direction very quickly, before faulting. This has made it nigh impossible to get anywhere, as the method I'm using to tune the loop (Wikipedia) needs the loop to hit the setpoint.

At a stable P(no sad gear grinding) the output is much lower than the setpoint, and as P is increased to hit the setpoint, the loop gets more prone to the gear grinding. I've yet to even begin to play with the I value, as I fear it may lead to more instability.