Servo Tuning detailed How To.

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08 Mar 2017 04:30 #89189 by Todd Zuercher
In that case you should be good, and you shouldn't need to mess with the drive tuning, as it should have already been done. Just tuning the position loop in Linuxcnc.
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09 Mar 2017 13:18 #89252 by andypugh

superlen wrote: The drives are configurable so I can configure them for velocity or torque mode and let Linuxcnc do the tuning if necessary. I take it that is the most common way of configuring Linuxcnc (with it handling motion control). I keep thinking that the motion control should be outside the PC in embedded hardware, but I realize that with the power of Linux & RTOS this isn't as prevalent as it once was, particularly with a FPGA doing some of the heavy lifting in between.


The most common setup is a velocity-controlled servo drive (velocity loop in the drive, an tuned in the drive) and a position loop in LinuxCNC (tuned after the velocity loop is tuned)

The fundamental point of EMC (which became LinuxCNC) was to be a motion controller that ran on commodity PC hardware rather than on specialised hardware. Whereas Mach3 had commercial reasons to support external motion cards like the Smoothstepper, LinuxCNC has no such commercial incentives, so the philosophy is that LinuxCNC is a motion controllerm and if you don't want it to do that, then use something else. But I digress.

after studying the current setup in more detail, they aren't. They are receiving an analog voltage from a PCI motion card (similar to Mesa, but not supported by Linux CNC),


Are you sure? What card is it?

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14 Mar 2017 03:36 #89567 by superlen
Andy,

Thanks for the information on the velocity loop vs. position loop.

The drives are KollMorgen ServoStarCDs. The PCI card is an Acroloop 8020. With the reasonable price of the Mesa Cards it was way more obvious to just purchase and play, rather than write a driver. The Mesa ethernet version(s) simplifies some wiring for me as well.

Len

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14 Mar 2017 05:51 #89571 by tommylight
Had a look last night on some servostar drives, series 6 looks very nice. Found some 606 in Germany for 400 euro a piece used but i have no clue if they are worth that. Some new ones on fleebay go for over 1000. I like the adjustability of the output voltage, encoder passthrough, tacho feedback, several control types etc. Will have to check them in more detail.

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07 May 2017 21:59 #92791 by tommylight
Added to the original post:
some more info and details on I and D values,
some minor editing for easier understanding.
Regards,
Tom

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12 Apr 2018 22:05 #108912 by DaOne
Replied by DaOne on topic Servo Tuning detailed How To.
Is there a link to this axis screen with all the widgets somewhere?

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12 Apr 2018 22:14 #108915 by tommylight
Here you go.
Attachments:
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12 Apr 2018 22:39 #108919 by DaOne
Replied by DaOne on topic Servo Tuning detailed How To.
Thank you!

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13 Apr 2018 22:19 #108974 by tommylight

DaOne wrote: Thank you!


You are welcomed, always.
Also there is a button under each post for "thank you", if you have missed that.
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06 Aug 2019 05:38 #141478 by Type_Zero_Design
Tommy,

This was extremely informative! I'm excited to start my running. I have a few questions I hope you don't mind me asking here. (I think they may help other people as well)

First, my joint.N.f-error on all three joints dose not seem to be producing any results. I'm assuming that is because it is not using the encoder feedback for some reason. Under .hal configuration tool I can see my encoder counting and used it to determine my steps per rev initially, but I'm guessing that I missed something somewhere to tie this in and close the loop?

Second, when talking about the p value and it's initial adjustment. When you talk about the vibration, I can not physically feel a vibration in the servo motor itself, but after a jog I can audibly here faint vibration noise and if I put my hand on the screw I can feel the motor ever so slightly "vibrating" attempting to hold the position. Putting even very light pressure on the rotation of the screw physically and audibly changes that "vibration" it's almost more of a buzzing sound. My question being is this what you are considering vibration or is what your referring to something more aggressive? Also I'm guessing before messing with this and the P to much I should figgure out the joint.N.f-error situation first.

Lastly, will my accel/decell and velocity affect the tune. Should they be solidified prior to running? I'm not to sure on how to decide those numbers yet.

Thanks for any info!

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