PID

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01 Feb 2022 15:46 #233716 by Todd Zuercher
Replied by Todd Zuercher on topic PID
Did you follow one of the servo tuning tutorials, to tune your PID settings?
Such as this one:
gnipsel.com/linuxcnc/tuning/servo.html

You also need to view your f-error with a bit of perspective, the movement you are seeing there in that photo is only +/- a few encoder counts, with the largest peak only -7 counts. What is your encoder scale? Do you have a value for the dead band setting? Sometimes setting that to 1.5-2x the encoder scale can help to quiet a nervous joint at rest.

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02 Feb 2022 01:24 #233766 by cmorley
Replied by cmorley on topic PID

No movement, change in axis values, or halscope vibrations take place when drive is disabled...., I already tried a lot of values for pid..

 

Did you try the open loop test in pncconf?
It is used to confirm the analog setting actually moves the motors and that the encoders count in the right direction.

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03 Feb 2022 22:43 #233919 by Bahaa_Asem
Replied by Bahaa_Asem on topic PID
Why set the deadband to 1.5-2X the encoder scale? And how to know the encoder scale or check them if I calculated it wrong?

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05 Feb 2022 01:54 #234011 by Todd Zuercher
Replied by Todd Zuercher on topic PID
The encoder scale is the distance your machine moves for one encoder count. It is a setting in your ini config file. If the scale is set wrong the machine won't move the correct distance.

Having a small dead and setting can help to quiet servo dithering by telling the pid "your close enough.

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