Servo Tuning detailed How To.

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08 Mar 2017 04:30 #89189 by Todd Zuercher
Todd Zuercher replied the topic: Servo Tuning detailed How To.
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.
The following user(s) said Thank You: tommylight
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09 Mar 2017 13:18 #89252 by andypugh
andypugh replied the topic: Servo Tuning detailed How To.

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
superlen replied the topic: Servo Tuning detailed How To.
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
tommylight replied the topic: Servo Tuning detailed How To.
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
tommylight replied the topic: Servo Tuning detailed How To.
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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