Jumping motion with XHC-WHB04B pendant

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5 months 2 weeks ago #346381 by Ismacr63
I have an XHC-WHB04B pendant set up and everything works pretty well, except that when I turn the wheel in continuous mode it moves in jerks/jumps, while in step mode it moves smoothly. Is there any way to avoid the jumps in continuous mode?

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5 months 5 days ago #346612 by andypugh
I can't help with a fix, but it might help to work out where the fix belongs.
Try plotting the position-cmd in Halscope to see if the problem is in the commands from the WHB or is inside HAL itself.

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5 months 5 days ago #346616 by andrax
You may have set the deceleration and acceleration ramps too steeply 

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5 months 5 days ago #346621 by Ismacr63

I can't help with a fix, but it might help to work out where the fix belongs.
Try plotting the position-cmd in Halscope to see if the problem is in the commands from the WHB or is inside HAL itself.
I'm attaching a short video and my configuration files. I've been trying to use Halscope but I still don't quite understand it. Tomorrow with more time I'll give it another try.

youtube.com/shorts/L8vz-2Y_pZM?feature=share

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5 months 5 days ago #346660 by andrax
Yes, I experience this effect as well. It is caused by the fact that, when using the handwheel, you are constantly commanding a new target position for the axis. Even if you are only moving in small increments—0.01 mm or 1.00 mm at a time—the acceleration and deceleration ramps are still being applied. If these ramps are set too short, the axis accelerates and decelerates with every single increment, which is what causes the rattling sound.
You could address this by generally lengthening the ramps—though this would impact your machine's overall dynamics—or you could implement a specific solution within your XHC HAL configuration

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5 months 4 days ago #346672 by MaHa
Just talking from my experience, on my machine i got good result with ilowpass / multiply stepsize

setting for all axis:
MAX_ACCELERATION = 1100.0

If set Stepsize on mpg to 100 or less, it works very good. Even stepsize 500 worked, larger was not safe.
jog-counts and jog-scale can be set for all axis, only the enabled axis will move finally.
This config was made many years ago, thats all i remember

# The stepsize selected is always multiplied by 0.001
# ilowpass − Low-pass filter with integer inputs and outputs
# mult2 − Product of two inputs
Code:
loadrt ilowpass loadrt mult2 addf ilowpass.0 servo-thread addf mult2.xhc servo-thread # Lowpass Filtering for mpg setp ilowpass.0.gain 0.01 # IMPORTANT to keep ratio ilowpass.0.scale mult2.xhc.in1 setp ilowpass.0.scale 1000 setp mult2.xhc.in1 0.001 net jog-counts_in  <=  xhc-hb04.jog.counts => ilowpass.0.in net jog-counts_out <=  ilowpass.0.out      => joint.0.jog-counts axis.x.jog-counts joint.1.jog-counts axis.y.jog-counts joint.2.jog-counts axis.z.jog-counts net jog-scale      <= xhc-hb04.jog.scale   => mult2.xhc.in0 net scale_div_1000 <=  mult2.xhc.out       => joint.0.jog-scale axis.x.jog-scale joint.1.jog-scale axis.y.jog-scale joint.2.jog-scale axis.z.jog-scale # Switch to mode.manual net man_mode       <= xhc-hb04.button-mode => halui.mode.manual
 

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5 months 1 day ago #346745 by Sascha H.
You can try this in your hal-file:
Code:
setp axis.x.jog-accel-fraction 0.4 setp axis.y.jog-accel-fraction 0.4 setp axis.z.jog-accel-fraction 0.4

This reduces the acceleration of the axes when moving with the pendant.

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1 month 2 weeks ago #349593 by muddiver
Hi Sascha,

i wanted to thank you, you made my day with your hint, that's what it needed to get the smooth Handwheelfeeling i wanted!

Greets, Tom

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