autotuning servo motor

[unsaint32]

I am autotuning a servo motor (with Kinetix 300) using Motionview Onboard.

#1) About autotuing's travel limit. I don't know what it is. When I first opened the autotune dialogue box, the travel limit was 0.0832 User Unit. With that, the autotune was done successfully. Then, I changed the travel limit to 0.5 User Unit. Again, the autotune was successful.
So, I assume the travel limit has to be large enough for the motor movement required for autotuning. But also the travel limit has to be limited so the tuning's motor movement does not cause some load crashing into obstacle? Am I right?


#2) Also, everytime I do autotune (even with the same travel limits), I get slightly different values like the following 3 sets of values. Are the differences here non-important?

Velocity P-Gain : 13770.619
Velocity I-Gain : 2567.7988
Gain Scaling : -3

Velocity P-Gain : 14229.682
Velocity I-Gain : 2752.6543
Gain Scaling : -3

Velocity P-Gain : 14032.166
Velocity I-Gain : 2714.4458
Gain Scaling : -3

 

[treellama]

1) I don't remember. It's been a couple years since I've tuned in MotionView. I suspect that's just a limit that stops the motor if it moved too far during the autotune.

2) Those values look "the same" to me. The gains look they change about +/- 2%. That's well within the range I would expect, especially for MotionView.

I had poor luck with the onboard autotune - it didn't really seem to have any knobs to turn to adjust the results.

 

[Peter Nachtwey]

Ditto treellama's points 1 and 2

The gain values may be relatively consistent but they don't look right.
I good question is why don't they look right.
The integrator gain should be larger than the proportional gain unless the system is very ( extremely ) sluggish.
Why?

I should start a thread about auto tuning some time.

There are auto tuners and then there are real auto tuners. Many auto tuners are very crude and exist only so the marketing guys can claim they have an auto tuner.