Jaguar Speed Control Only Reaches 50% of Setpoint

[Mr. Lim]

Originally Posted by 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.

My workaround has been to tune the P-only loop to react as best as can be to exactly half the setpoint.

I can confirm that when you crank the P to actually try and hit the setpoint, bad things happen. It'll get you there, only to slam in reverse, and oscillate around the setpoint...

I'll get a chance to add I term to see if it will actually get me to the setpoint in a stable manner.

I'm curious if anyone know exactly how the Jaguars deal with Integral wind-up. Whether it reduces the I-term to 0 once the setpoint is hit, or does it cap the accumulated I value to some kind of ceiling?

Either way, I think we'll get a chance to find out tomorrow!