Servo Tuning detailed How To.

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01 Sep 2019 22:05 #143814 by Type_Zero_Design
Andy,

I'm not sure if you were referring to my post or Randy's with the oscillations but I'm guessing mine.

This is a shot of the settings in that vid.

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01 Sep 2019 22:43 #143817 by andypugh
I have no idea who I am talking to, or about what any more.

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02 Sep 2019 03:26 #143853 by Type_Zero_Design
Andy,

Sorry for the confusion, for clarity and not to muddy the waters anymore I have made my own post to continue my tuning endevor.

forum.linuxcnc.org/10-advanced-configura...ther-tc-225-retrofit

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09 Oct 2019 19:50 #147592 by HueyHQ

On my retrofit, I had a lot of trouble tuning following all the advice I had found because I had entered an arbitrary value for the acceleration parameter (way too high). It wasn't until I bumped it down to something more in line with what I had seen in others config files, that I could even start to tune my servos. My machine works fine now, but doesn't move as fast as it did before the retrofit, so I could go back and refine the tuning with higher accel params.!

Recently, I found my X-axis was oscillating really badly when routing out complex shapes. Straight X and Y cuts were fine but diagonal was the worst, unless I really slowed down the feed.

I was never really satisfied with the tuning, so I re-visited it yesterday.
What I found is, if I reduce to P = 0.1, the movements are now as smooth as silk, leading me to believe that the PID is possibly done in the servo amps? To those who know more about this than I do, does this sound right? (I have attached the driver manual in case that sheds any light, for anyone who is THAT interested!)

Setting P = 0 causes a following error, so what would be the lowest I should set it to, or is 0.1 OK?

I've also tuned FF1 = 0.00727 and FF2 = 0.00001 to get a reasonably flat (albeit very noisy) halscope'd f-error.
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09 Oct 2019 20:21 #147594 by tommylight
If it works at 0.1, leave it at that.
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14 Nov 2020 09:38 #189308 by viesturs.lacis
I am trying to tune servo loop based on this tutorial. What I see during the process is that as I jog the motor and release the arrow button, motor should decelerate and stop. At the moment of key release there is a sudden drop in velocity, which then resumes and after that the motor stops, see attached picture. Is that related to PID tuning or is that a lag in GUI or something similar?
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14 Nov 2020 10:11 #189314 by tommylight
Are you tuning the old Yaskawa drives with encoder feedback from the drives to 7i77? Those should be very easy to tune, just set the P value till the motors start to vibrate then lower it a bit so there is no or very litle vibration, then add FF1 a bit. Leave everything else at 0 excpet the deadband.
That should be it, it literarly took 5 minutes to tune all 3 axis last time i used them.
Make sure you have the drive enable wired to LinuxCNC and working correctly before everything else.

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14 Nov 2020 11:57 #189320 by bevins

I have no idea who I am talking to, or about what any more.


I feel like that all the time.....Time to retire I think.
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14 Nov 2020 13:26 #189330 by viesturs.lacis

Are you tuning the old Yaskawa drives with encoder feedback from the drives to 7i77? Those should be very easy to tune, just set the P value till the motors start to vibrate then lower it a bit so there is no or very litle vibration, then add FF1 a bit. Leave everything else at 0 excpet the deadband.
That should be it, it literarly took 5 minutes to tune all 3 axis last time i used them.
Make sure you have the drive enable wired to LinuxCNC and working correctly before everything else.


I have 7i48 for servo control, but other than that - yes, it was pretty easy to tune motor for X axis. The table is too short to safely jog it at 45m/min, while looking at PC screen... Now I have to sort out missing encoder signal from Y motor.

BTW can you share some suggestions for controlling the VFD? At least some hints about wiring and pinout on VFD control signal terminal?

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14 Nov 2020 18:23 #189358 by tommylight

BTW can you share some suggestions for controlling the VFD? At least some hints about wiring and pinout on VFD control signal terminal?

Vhat VFD? Any schematics ?

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