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A Axis creeping - Bias not fixing it - axis not responding to jog buttons
- B.Reilly01
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1 year 9 months ago #319319
by B.Reilly01
I'm attempting to add a 4th axis to my mill, but I'm running into roadblocks. The axis jogs (but still creeps) under "open loop testing" in PNCCONF. When I launch ProbeBasic, it no longer jogs (while the other axes do), and it creeps at a rate of about 1/2 degree per second. Adding bias doesn't seem to effect it. PID is not tuned yet. When I try to jog it it following error errors out instantly. As you can see in my INI file, I set the following error to 5 degrees to be able to see how fast it was creeping. What are reasonable numbers for accel for a 4th axis?
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1 year 9 months ago #319320
by PCW
Replied by PCW on topic A Axis creeping - Bias not fixing it - axis not responding to jog buttons
if you get a continuous creep, it indicates a problem with feedback.
(backwards, noise generating false counts, PID with no P term etc)
(backwards, noise generating false counts, PID with no P term etc)
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1 year 9 months ago #319329
by B.Reilly01
Replied by B.Reilly01 on topic A Axis creeping - Bias not fixing it - axis not responding to jog buttons
I'm seeing the DRO move with the creeping (that's how I identified the creep), I disconnect the analog output to the drive and it stops, I'm measuring 10mv about on the output to the drive, so the creep is being generated by the control. I tried switching the Encoder direction, no change.
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1 year 9 months ago #319340
by tommylight
Replied by tommylight on topic A Axis creeping - Bias not fixing it - axis not responding to jog buttons
Up the P value, check by hand if that stiffens the shaft after clicking on "test".
Are you using the "calibration" from the "machine" menu?
Are you using the "calibration" from the "machine" menu?
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1 year 9 months ago #319343
by PCW
Replied by PCW on topic A Axis creeping - Bias not fixing it - axis not responding to jog buttons
With a 10 mv offset and a P gain of 150 it should only take
0.0000666667 inches of following error to zero the bias.
Continuous creeping means an feedback issue of some kind.
I tried switching the Encoder direction, no change.
If feedback was working, this would cause an instant runaway.
0.0000666667 inches of following error to zero the bias.
Continuous creeping means an feedback issue of some kind.
I tried switching the Encoder direction, no change.
If feedback was working, this would cause an instant runaway.
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1 year 9 months ago #319379
by B.Reilly01
Replied by B.Reilly01 on topic A Axis creeping - Bias not fixing it - axis not responding to jog buttons
Ya'll are great help - I went searching for differences between the axes in the INI and HAL since the encoder switch should have been a major problem and I found that I didn't add the do.pid.calcs to the servo thread for the a axis (addf pid.a.do-pid-calcs servo-thread). Now I got a tuneable axis with WAY too much coast (possibly a drive param issue), but now I have an axis that obeys at least. On to tuning!
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