Anyone installed Mechaduinos on a printer yet?
I’ve got them working on X/Y, but need to tune the PID better.
Here are the settings I’m currently running. Normal operation is ok, but there’s still a fair bit of bounce on error correction
I’ve also tried no integral and no derivative per the recommendations…
Asking out of ignorance here, but is there a library available with a PID autotune? The autotune in Marlin wasn’t implemented from scratch, was it?
Could the bounce be caused by elasticity in the mechanics that isn’t visible to the encoder?
Marlin’s autotune is derived, if you go back far enough, from some LabView PID demo code, if I recall correctly. (By way of some Arduino PID demo code.) That technique (relay method) only works particularly well for first-order processes, so I don’t think it’ll be very effective for a stepper driven drivetrain… Could be wrong though.
Have you checked what the reflected inertia ratio is for the moving mass versus the rotor mass? That’s often an issue with servo tuning. There’s no guarantee PID feedback is suitable for all drivetrain configurations.
@Ryan_Carlyle No, but I just realized that the calibration process was done with no load on it. I’m going to redo that and see what shakes out.
I really need to get mine installed in a printer and do some fiddling. Won’t have a chance for a few months until after we move though.