background:
cincinatti 10hc horizontal mill (approx weight 40 thou pounds)
SEM 221 in/lb servos
z-axis: 3rev-inch ballscrews (moving approx 10 thou pounds front/back)
1000-line encoders
Galil DMC 1860 controller
So, after spending several months trying to tune-out velocity-mode amps, using torque-mode methods... :withstupi i finally realized why nothing was working out right!... swapped over to torque mode on the amps.. now everything is going MUCH better...
my problem however is this. I've been using galil wsdk software to tune these, and was running a 1000 line pulse for step response moves. had things tuned out, or so i thought.. 15 cnts following error and decent steady-state holding. then, went to a 100 cnt pulse, and realized my steady-state error was wandering +- 5 counts.
i've tried to damp this out more, but just end up with a servo that REALLY wants to sing on short moves. introduced some pretty hefty pole filter to cut down on that, but still don't feel i'm where i should be.
current settings kP: 275 kD: 2000: kI:havne't decided yet how much to drop in
i'm looking for any ideas/assistance that people might be able to offer. getting SOO close to having this machine up & running where i can be happy, and now i feel like i'm chasing my tail.. argh....
thanks in advance all!
-nate