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Servo Wiring and Tuning detailed How To example Mesa 7i77.
29 Aug 2019 22:42 #143612
by PCW
Replied by PCW on topic Servo Wiring and Tuning detailed How To example Mesa 7i77.
Sounds like is it running in torque mode ( are there tachometers at all? )
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- randypetersen
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29 Aug 2019 22:49 #143613
by randypetersen
Replied by randypetersen on topic Servo Wiring and Tuning detailed How To example Mesa 7i77.
There is a "TACH" input on the driver, but I don't have anything connected to it, and I checked the old ribbon controller that was connected to the old controller and the TACH pin wasn't used either. Only thing coming from motor is Power and Encoder (i believe) and brake for Z.
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30 Aug 2019 02:25 #143627
by randypetersen
Replied by randypetersen on topic Servo Wiring and Tuning detailed How To example Mesa 7i77.
Having difficulty finding any servo tuning information on servos operating in TORQUE mode. Does anyone know of any tuning resources for me?
Thanks
Thanks
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30 Aug 2019 03:12 #143628
by PCW
Replied by PCW on topic Servo Wiring and Tuning detailed How To example Mesa 7i77.
A _very_ rough guide is this (for a single PID loop/Axis)
Start with FF1=0 and FF2 = 0 and I=0
Chose a small amount of P (say 50 = full torque with 1/5" error)
Then increase D until it gets too "buzzy" and then back off about 30% on D
Then increase P until you get oscillations and again back off about 30%
Then adjust FF2 so that you neither overshoot or undershoot during
acceleration (the FF2 setting is inertia dependent so its better to do this with a typical table load)
Finally increase I until motion becomes unstable (Watch out for WIDE oscillations here)
and back off about 50%
Start with FF1=0 and FF2 = 0 and I=0
Chose a small amount of P (say 50 = full torque with 1/5" error)
Then increase D until it gets too "buzzy" and then back off about 30% on D
Then increase P until you get oscillations and again back off about 30%
Then adjust FF2 so that you neither overshoot or undershoot during
acceleration (the FF2 setting is inertia dependent so its better to do this with a typical table load)
Finally increase I until motion becomes unstable (Watch out for WIDE oscillations here)
and back off about 50%
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30 Aug 2019 18:09 #143677
by BigJohnT
Replied by BigJohnT on topic Servo Wiring and Tuning detailed How To example Mesa 7i77.
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30 Aug 2019 18:16 #143678
by PCW
Replied by PCW on topic Servo Wiring and Tuning detailed How To example Mesa 7i77.
Its still valid (just more conservative)
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- Type_Zero_Design
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30 Aug 2019 19:06 #143684
by Type_Zero_Design
Replied by Type_Zero_Design on topic Servo Wiring and Tuning detailed How To example Mesa 7i77.
Just Bumping this up for any feedback on next step to eliminate the osculation following the command in the video linlk.
Todd,
I posted a link to a video of my hall scope with the error in the post with my current settings a post back, but I know it's kind of an unconventional way to post a video so I've included it here as well( It won't let me upload directly)
photos.app.goo.gl/eiimAkZXWb9CGVqG6
Hopefully that's viewable for others, I'm not 100% sure it's from my Google drive.
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01 Sep 2019 19:30 #143804
by andypugh
Replied by andypugh on topic Servo Wiring and Tuning detailed How To example Mesa 7i77.
That's pretty slow to be P-term oscillation. Do you have any I term?
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01 Sep 2019 19:47 #143807
by randypetersen
Replied by randypetersen on topic Servo Wiring and Tuning detailed How To example Mesa 7i77.
My X and Y are both:
P:1500
I:1000
D:4
BIAS:0
FF0:0
FF1:0
FF2: 0.1
Deadband:.0001
Z:
P:50
I:1
D: 0.7
BIAS:0
FF0:0
FF1:0
FF2: 0.02
Deadband:.0001
Still got work to do.. but performing way better now. Still has issues when command a move less than 1", so I will keep working on it, thanks for everyone's help!
P:1500
I:1000
D:4
BIAS:0
FF0:0
FF1:0
FF2: 0.1
Deadband:.0001
Z:
P:50
I:1
D: 0.7
BIAS:0
FF0:0
FF1:0
FF2: 0.02
Deadband:.0001
Still got work to do.. but performing way better now. Still has issues when command a move less than 1", so I will keep working on it, thanks for everyone's help!
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01 Sep 2019 19:51 #143809
by andypugh
Replied by andypugh on topic Servo Wiring and Tuning detailed How To example Mesa 7i77.
I=1000 with P=1500 looks wrong. I is typically a very small fraction of P.
I think you are seeing an I-term oscillation there.
I think you are seeing an I-term oscillation there.
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