Howard Chan wrote: > Dear Jon, > Today I tune the PID again. Would you mind help me to check the value > and give me some suggestion? Thank you! > > [TRAJ] > DEFAULT_VELOCITY = 13.30 > MAX_VELOCITY = 33.34 > DEFAULT_ACCELERATION = 45.0 > MAX_ACCELERATION = 50.0 > > [AXIS_1] > MAX_VELOCITY = 50.0 > MAX_ACCELERATION = 50.0 > BACKLASH = 0.000 > INPUT_SCALE = -2835 > > When P=20, I=50, D=0, FF1=0, FF2=0 and click 'F2' > http://myweb.polyu.edu.hk/~icwfchan/p1.png > > When P=20, I=50, D=0, FF1=0.198, FF2=0 and run 'Y=20' > http://myweb.polyu.edu.hk/~icwfchan/p2.png > > When P=20, I=50, D=0, FF1=0.198, FF2=0.00021 and run 'Y=20' > http://myweb.polyu.edu.hk/~icwfchan/p3.png > First trace is just the settling of the servo when it goes from open- to clesed-loop. 2 later traces show you need more FF2, increase in small increments. I think you could use more P gain, less I (at least until all other tuning is done) and a bit of D to damp out the fluctuation in the error. If that error scale factor is 2 milli-mm (2 um) per division, then maybe just work on the FF2 and damping, I doubt you can improve much on the rest.
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