Re: Tuning a PIDF follower on a robot with high gearing
PID(F) assumes linear dynamics; the high voltage and low voltage operating points of DC motors attached to a substantial load behave quite differently.
You will have the best luck if you tune the feedforward terms near the setpoints you care about (or if you want, gain schedule so that no matter what the velocity setpoint, you have a suitable set of feedforward gains).
On 254 we typically tune around a "nominal" speed and accept that at very low speeds, the feedback part of the controller is doing more of the work (which for us usually only occurs briefly at the beginning or end of a motion profile). If we had to spend a large amount of time cruising at a different speed, we would probably gain schedule.