Yes, I know, "tuning PID controllers is more art than fixed procedure", but I could do with a little help nevertheless.
Some background: this is for a recumbent bike with Grin all-axle motor, baserunner, 52V battery and a CAv3. I've been riding it for more than a year with the max assist speed handled by the controller, which meant I could use the CAv3's max speed parameter to control regen speed (via a potentiometer in analog aux input). Max assist speed regulation was excellent (with the default parameters for the all-axle - P=4 and I=16 IIRW). Regen speed regulation never was very good, but it was good enough that I never was motivated enough to try and fine tune it.
Now I upgraded my CA to firmware 3.2, which allows to set max assist and regen speed separately, so my goal is to have all regulations done by the CA. But the PID parameters I've got are really too bad to get a smooth ride. Huge overshoots, long settling times, instability, I've got them all :-/
I tried to follow the procedure suggested in Appendix F of the unofficial CA guide but that's very time consuming and far from easy. For instance, the suggested initial PSGain already shows a huge overshoot so I'm not sure it makes sense to "Increase PSGain to the point where a single modest overshoot occurs before the speed settles". And instructions like "Increase IntSGain until oscillations die out [...]* are difficult to follow if I have no idea of the approximate value (should I increase 1 by 1? 10 by 10? 100 by 100?).
So if somebody here had an idea of approximate values for P, I and D that should work with this setting, it would help immensely. I could then spend some time fine tuning them, but knowing e.g. if D is supposed to be around 5 or 5000 would make a huge difference!
Some background: this is for a recumbent bike with Grin all-axle motor, baserunner, 52V battery and a CAv3. I've been riding it for more than a year with the max assist speed handled by the controller, which meant I could use the CAv3's max speed parameter to control regen speed (via a potentiometer in analog aux input). Max assist speed regulation was excellent (with the default parameters for the all-axle - P=4 and I=16 IIRW). Regen speed regulation never was very good, but it was good enough that I never was motivated enough to try and fine tune it.
Now I upgraded my CA to firmware 3.2, which allows to set max assist and regen speed separately, so my goal is to have all regulations done by the CA. But the PID parameters I've got are really too bad to get a smooth ride. Huge overshoots, long settling times, instability, I've got them all :-/
I tried to follow the procedure suggested in Appendix F of the unofficial CA guide but that's very time consuming and far from easy. For instance, the suggested initial PSGain already shows a huge overshoot so I'm not sure it makes sense to "Increase PSGain to the point where a single modest overshoot occurs before the speed settles". And instructions like "Increase IntSGain until oscillations die out [...]* are difficult to follow if I have no idea of the approximate value (should I increase 1 by 1? 10 by 10? 100 by 100?).
So if somebody here had an idea of approximate values for P, I and D that should work with this setting, it would help immensely. I could then spend some time fine tuning them, but knowing e.g. if D is supposed to be around 5 or 5000 would make a huge difference!