Tuning AMC BE25A20 drive

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03 Apr 2020 16:08 #162592 by Catch22
Ok so I have everything wired up to 7i77 and drives in velocity mode with tach and linear scales and all seems ok, but I don't think the drives are properly tuned and before I try tuning Linuxcnc I would like to go back and try to tune them. Can this be done now, I can't seem to run the servo motors without Linuxcnc to get them to run. I read that I need to tune the drives by themselves first. Just not sure how to go about it now.

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03 Apr 2020 16:47 #162595 by PCW
Replied by PCW on topic Tuning AMC BE25A20 drive
You can use LinuxCNC for this tuning by simply setting the P term to 0
When you do this, there is no feedback from LinuxCNC and the velocity
command (analog output voltage) is simply FF1 * velocity in machine
units/second.

So with this setup you can just use jogging to issue velocity commands
and see how well the drives follow the commands by HALScoping the
analog output and encoder velocity signals

Note that with no P term you will have position drift, so adding a tiny bit of P (say 0.05)
will keep the position in control without interfering with the drive tuning
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03 Apr 2020 16:53 #162596 by Catch22
Replied by Catch22 on topic Tuning AMC BE25A20 drive
Thanks again PCW, I don't know how I would ever be able to do this stuff without you and the other nice people on this forum willing to help us out.
Thanks too everyone and if I can in the future I will pay it forward.
Thanks Mike

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04 Apr 2020 08:31 #162651 by cmorley
Replied by cmorley on topic Tuning AMC BE25A20 drive
Do you have the tuning PDF for AMC drives?
I might have a copy if you need.
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04 Apr 2020 12:49 #162671 by Catch22
Replied by Catch22 on topic Tuning AMC BE25A20 drive
Chorley I don't have a copy, that would be great if you could send me a copy.
Thanks very much.

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04 Apr 2020 13:32 #162675 by OT-CNC
Replied by OT-CNC on topic Tuning AMC BE25A20 drive
Some more info in my thread that may be helpful to you. In order to do the velocity tuning with linuxcnc, you need to know and set the motor rpm at 10v first to get your desired rapid. Without encoders on the motor, you can't easily figure out your rpm, you'll need some other method to determine it. I used an external rpm meter pointing at the motor pulley (belts removed). You adjust the drive reference gain to get to your target number at 10v. Check -10v also to confirm if things look correct. You enter ips values in the ini and that should get you a close starting point. Otherwise you're just guessing.

amc drive tuning
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04 Apr 2020 14:46 #162677 by Catch22
Replied by Catch22 on topic Tuning AMC BE25A20 drive
How do you know if it's at 10v just by using a voltage meter?

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04 Apr 2020 15:45 #162683 by Catch22
Replied by Catch22 on topic Tuning AMC BE25A20 drive
Doesn't seem like the 4 potentiometers do anything? You can turn them forever and nothing happens, wondering if they are broken?

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04 Apr 2020 16:43 #162685 by cmorley
Replied by cmorley on topic Tuning AMC BE25A20 drive
here are is a data sheet and a tuning procedure.
There is another available from AMC website - it's too big to post here.
I'll see if I can find a link
Attachments:
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04 Apr 2020 16:44 #162686 by cmorley
Replied by cmorley on topic Tuning AMC BE25A20 drive
ahh they require sign up now - too bad they used to be really great about old drive support.
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