Jumping motion with XHC-WHB04B pendant

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13 May 2026 20:30 #346381 by Ismacr63
Jumping motion with XHC-WHB04B pendant was created 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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25 May 2026 17:12 #346612 by andypugh
Replied by andypugh on topic Jumping motion with XHC-WHB04B pendant
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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25 May 2026 17:30 #346616 by andrax
Replied by andrax on topic Jumping motion with XHC-WHB04B pendant
You may have set the deceleration and acceleration ramps too steeply 
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25 May 2026 21:35 #346621 by Ismacr63
Replied by Ismacr63 on topic Jumping motion with XHC-WHB04B pendant

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
Attachments:

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26 May 2026 07:50 #346660 by andrax
Replied by andrax on topic Jumping motion with XHC-WHB04B pendant
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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26 May 2026 19:16 #346672 by MaHa
Replied by MaHa on topic Jumping motion with XHC-WHB04B pendant
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
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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29 May 2026 18:44 #346745 by Sascha H.
Replied by Sascha H. on topic Jumping motion with XHC-WHB04B pendant
You can try this in your hal-file:
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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