Jaguar Speed Control Only Reaches 50% of Setpoint

[kamocat]

Originally Posted by Mr. Lim

Can you confirm that a P-Only control loop will only get you half-way to the setpoint?

I have some concerns that the speed control mode on the Jags is missing some important functionality.

If the P term doesn't accumulate in velocity control, it will go to 0 as it gets closer to the setpoint. This usually results in a P-only loop appearing stable, but only hitting about 50% of the setpoint.

A workaround is to have an I term that will get you all the way to the setpoint. However, I've heard elsewhere that the I term goes to zero as soon as the setpoint is attained, so as to prevent overshoot/wind-up. I can't confirm this 100%, but based on some initial testing I'm led to believe this is the case, as an I-only loop seems to hit the setpoint, then cuts out, only to accelerate up to the setpoint and cut out again.

Right now, we're using a P-only loop, setting the setpoint twice as high as we really want it. It's a sloppy workaround, but the best we've come across so far.

Yes, without an I coefficient, you can't expect to ever reach the setpoint; you get partway there, and then don't go any further.

I haven't tried an I-only loop.

If you're intent on using P only, what happens when you double your P coefficient? Is that the point where it starts to oscillate?