MPG causing axis oscillations.
31 Mar 2016 18:28 #72484
by PCW
Replied by PCW on topic MPG causing axis oscillations.
That really makes no sense, what is the ilowpass scale? (I would not reccomend less than 1000)
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31 Mar 2016 19:01 #72486
by PCW
Replied by PCW on topic MPG causing axis oscillations.
There does seem to be something wrong with the stepgen but its not obvious what
as this is not a common problem.
Can you plot the following error and velocity during a jog with halscope and post it here?
That would help at lot to understand whats happening here
as this is not a common problem.
Can you plot the following error and velocity during a jog with halscope and post it here?
That would help at lot to understand whats happening here
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31 Mar 2016 19:16 #72488
by eman5oh
Replied by eman5oh on topic MPG causing axis oscillations.
I will run the test tonight and post the results. The issue only occurs when jogging with the mpg in .100 per click mode. I have not cut any parts on the machine yet but have run several g-code files without issue. The machine jogs fine with the keyboard as well. I am not an expert programmer so there may be an error in my hal files. I have attached my latest one with ilowpass . Thanks for the help with this.
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31 Mar 2016 22:37 #72494
by eman5oh
Replied by eman5oh on topic MPG causing axis oscillations.
Here is the hal scope log file.
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31 Mar 2016 23:47 #72497
by PCW
Replied by PCW on topic MPG causing axis oscillations.
Hmm... a halscope screenshot would be a bit easier to interpret ![:-) :-)](/media/kunena/emoticons/smile.png)
Looks like something basic is broken maybe servo thread rate is not as expected or PCI clock is wrong
I would try setting the maxerror to 0 and seeing if that helps
The other option is to tune FF1 (assuming a clock issue)
Is this a 5I25 card? (you can easily break the stepgen on a 6I25 by getting the clocks wrong)
![:-) :-)](/media/kunena/emoticons/smile.png)
Looks like something basic is broken maybe servo thread rate is not as expected or PCI clock is wrong
I would try setting the maxerror to 0 and seeing if that helps
The other option is to tune FF1 (assuming a clock issue)
Is this a 5I25 card? (you can easily break the stepgen on a 6I25 by getting the clocks wrong)
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01 Apr 2016 01:04 #72498
by eman5oh
Replied by eman5oh on topic MPG causing axis oscillations.
It is a 5i25, What does FF1 do? The odd thing is running gcode max error following error is around .00007in. This only happens when using the MPG.
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01 Apr 2016 03:23 - 01 Apr 2016 12:30 #72502
by PCW
Replied by PCW on topic MPG causing axis oscillations.
Strange, you might try reducing the P gain
Also your example file has
setp ilowpass.0.scale 1
This means that smoothing cannot work (as I said 1000 is a reasonable minimum for ilowpass scale)
Make sure you reduce the jog increments to match the scale change
Also your example file has
setp ilowpass.0.scale 1
This means that smoothing cannot work (as I said 1000 is a reasonable minimum for ilowpass scale)
Make sure you reduce the jog increments to match the scale change
Last edit: 01 Apr 2016 12:30 by PCW.
The following user(s) said Thank You: eman5oh
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02 Apr 2016 00:51 #72540
by eman5oh
Replied by eman5oh on topic MPG causing axis oscillations.
So I set ilowpass scale to 1000, ilowpass to .01 per the exampl and adjusted my jog incremants by 1000 offset the ilowpass scale. This looks to have completely fixed my issue. I just jogeed the machine around for about 1/2 hour with the mpg on all axis and not a single following error or oscillation. Thanks for the help, I can now say for sure that my future cnc builds will be running Mesa cards.
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02 Apr 2016 20:11 #72579
by PCW
Replied by PCW on topic MPG causing axis oscillations.
I'm glad the low pass filter fixed the following error during jogging problem.
I have been thinking about how this can happen and after looking at the plot, I suspect its a combination of
MPG jogging slight exceeding the stepgens accel limits, your quite low machine acceleration settings
and the fact that once the stepgens acceleration limits are exceeded, the PID loop is no longer running
in proportional mode so can become unstable. I will see what can be done about this so it does not bite anyone else
I have been thinking about how this can happen and after looking at the plot, I suspect its a combination of
MPG jogging slight exceeding the stepgens accel limits, your quite low machine acceleration settings
and the fact that once the stepgens acceleration limits are exceeded, the PID loop is no longer running
in proportional mode so can become unstable. I will see what can be done about this so it does not bite anyone else
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04 Apr 2016 11:55 #72701
by andypugh
I am pretty sure you can open the file in Halscope then zoom / pan scale etc. In principle it is a lot more useful than a screen shot.
Replied by andypugh on topic MPG causing axis oscillations.
Hmm... a halscope screenshot would be a bit easier to interpret
I am pretty sure you can open the file in Halscope then zoom / pan scale etc. In principle it is a lot more useful than a screen shot.
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