MPG choppy motion

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24 Apr 2024 00:46 #298953 by natholego11
Good evening,
I recently got a 4 axis pendant similar to this one. PCW helped tremendously with getting it wired up and getting the firmware for my 7i96 working.  Thank you Peter!

now that I have motion, I am getting very choppy movements on the actual machine, is there a way to smooth out the motion coming from the pendant?  I read a little about lowpass filters, not sure if that would be a good route to go, but im not entirely sure how to incorporate it into my hal file.

I have a custom hal for the pendant inputs.

Any feedback on this would be much appreciated!
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24 Apr 2024 02:00 #298958 by spumco
Replied by spumco on topic MPG choppy motion
axis.L.jog-accel-fraction is the first thing to try.



"1" = 100% accel value set in the INI file for that axis

Add ("L" is the axis letter):

setp axis.L.jog-accel-fraction 0.5

to your hal file for each axis and see if it helps.  You can even turn it down farther, but be cautious as too low of a setting can result in 'lazy' responses to the MPG.

 
The following user(s) said Thank You: Clive S

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24 Apr 2024 11:21 #298983 by natholego11
Replied by natholego11 on topic MPG choppy motion
Thank you, Ill try this tonight. would it look something like this:
# This file will not be overwritten when you run PNCconf again

# if MPG outputs a quadrature signal per click set x4-mode to 1
# if MPG outputs 1 pulse per click set x4-mode to 0



#             --- JOG INCREMENTS---

# --- JOG-INCR-A ---
net jog-incr-a     <=  hm2_7i96.0.inm.01.input-08-not

# --- JOG-INCR-B ---
net jog-incr-b     <=  hm2_7i96.0.inm.01.input-09-not

# --- JOG-INCR-C ---
net jog-incr-c     <=  hm2_7i96.0.inm.01.input-12-not

#            --- JOINT SELECTIONS ---

 #--- JOINT-SELECT-X ---
net joint-select-x     <=  hm2_7i96.0.inm.01.input-02-not

# --- JOINT-SELECT-Y ---
net joint-select-y     <=  hm2_7i96.0.inm.01.input-03-not

# --- JOINT-SELECT-Z ---
net joint-select-z     <=  hm2_7i96.0.inm.01.input-04-not

# --- JOINT-SELECT-A ---
net joint-select-a     <=  hm2_7i96.0.inm.01.input-05-not


# ---jogwheel signals to mesa encoder
net axis-selected-count     <= hm2_7i96.0.inm.01.enc0-count

# section 5
#       for axis x MPG
# uncomment the jog-vel-mode you want to use
# comment out the ones you dont
# mode 1 is typically used
#setp    axis.x.jog-vel-mode 0
setp    axis.x.jog-vel-mode 1
setp    axis.x.jog-accel-fraction 0.5
#
net selected-jog-incr    =>  axis.x.jog-scale
net joint-select-x       =>  axis.x.jog-enable
net axis-selected-count =>  axis.x.jog-counts

# section 6
#       for axis y MPG
# uncomment the jog-vel-mode you want to use
# comment out the ones you dont
# mode 1 is typically used
#setp    axis.y.jog-vel-mode 0
setp    axis.y.jog-vel-mode 1
setp    axis.y.jog-accel-fraction 0.5
#
net selected-jog-incr    =>  axis.y.jog-scale
net joint-select-y       =>  axis.y.jog-enable
net axis-selected-count =>  axis.y.jog-counts 

# section 7
#       for axis z MPG
# uncomment the jog-vel-mode you want to use
# comment out the ones you dont
# mode 1 is typically used
#setp    axis.z.jog-vel-mode 0
setp    axis.z.jog-vel-mode 1
setp    axis.z.jog-accel-fraction 0.5
#
net selected-jog-incr    =>  axis.z.jog-scale
net joint-select-z       =>  axis.z.jog-enable
net axis-selected-count =>  axis.z.jog-counts   


#NOT USED-----1 of the below axis must be be commented out ( sections 8-10 )----NOT USED
# a and c are typically used
# section 8
#       for axis a MPG
# uncomment the jog-vel-mode you want to use
# comment out the ones you dont
# mode 1 is typically used
#setp    axis.a.jog-vel-mode 0
setp    axis.a.jog-vel-mode 1
setp    axis.a.jog-accel-fraction 0.5

net selected-jog-incr    =>  axis.a.jog-scale
net joint-select-a       =>  axis.a.jog-enable 
net axis-selected-count      =>  axis.a.jog-counts  

# section 9
#       for axis b MPG
# uncomment the jog-vel-mode you want to use
# comment out the ones you dont
# mode 1 is typically used
#setp    axis.b.jog-vel-mode 0
#setp    axis.b.jog-vel-mode 1
#net selected-jog-incr    =>  axis.x.jog-scale
#net joint-select-b       =>  axis.x.jog-enable 
#net selected-count      =>  axis.x.jog-counts

# section 10
#       for axis c MPG
# uncomment the jog-vel-mode you want to use
# comment out the ones you dont
# mode 1 is typically used
#setp    axis.c.jog-vel-mode 0
#setp    axis.c.jog-vel-mode 1
#net selected-jog-incr    =>  axis.c.jog-scale
#net joint-select-c       =>  axis.c.jog-enable
#net axis-selected-count =>  axis.c.jog-counts 
   

# jog increment

# section 11
# note jog increments are in inches or standard measurements
# 
# make sure the setp jogincr.in## has a - next to its scale number
#
# if you want to reverse the encoder direction remove the -
# from its scale number
#setp hm2_7i96.0.inm.01.enc0-counter-mode 1

net jog-incr-a          =>  jogincr.sel0
net jog-incr-b          =>  jogincr.sel1
net jog-incr-c          =>  jogincr.sel2
net selected-jog-incr   <=  jogincr.out-f
    setp jogincr.debounce-time      0.200000
    setp jogincr.use-graycode       false
    setp jogincr.suppress-no-input  false
     setp jogincr.in00         0.1000
    setp jogincr.in01          0.1000
    setp jogincr.in02          0.0100
     setp jogincr.in03         0.0010
    setp jogincr.in04          0.0010
     setp jogincr.in05         0.0010
     setp jogincr.in06         0.0500
     setp jogincr.in07         0.1000
     setp jogincr.in08         0.1000
     setp jogincr.in09         0.1000
     setp jogincr.in10         0.1000
     setp jogincr.in11         0.1000
     setp jogincr.in12         0.1000
     setp jogincr.in13         0.1000
     setp jogincr.in14         0.1000
     setp jogincr.in15         0.1000        

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24 Apr 2024 15:55 #299006 by spumco
Replied by spumco on topic MPG choppy motion
Yep, looks like a good starting point.

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30 Apr 2024 01:09 #299363 by natholego11
Replied by natholego11 on topic MPG choppy motion
so, that helped on the X and Y axis. but the Z is still very choppy, almost regardless of what value I use there.

other thoughts?

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30 Apr 2024 01:43 #299365 by spumco
Replied by spumco on topic MPG choppy motion
Does it change at all when you set z-accel-fraction way low?  If not, you may have a typo in your hal file.

You can check if it's active using halshow.  Find the z-axis jog-accel-fraction pin/parameter and you can change it directly in halshow.

If the response changes a little, but not much... then do you have any mechanical issues? Backlash or sloppy ballscrew end bearings?

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04 May 2024 14:19 #299736 by natholego11
Replied by natholego11 on topic MPG choppy motion
its certainly working, if I turn it way low its very very delayed, but when I change the jog increments to .010" thats when it gets choppy. I have a gas strut for my counter balance, that could be causing some of the issues I suppose. I need to look at using a weight instead, but its pretty involved to do that.

either way, I turned the jog-accel function down to .1 and again its super delay, but still choppy.

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04 May 2024 21:34 #299752 by spumco
Replied by spumco on topic MPG choppy motion
I'm thinking the next test is to adjust Z-accel in INI file (or halshow) and write a little g-code program to move it up and down over the whole stroke.

Maybe start off with really low accel so it barely gets up to speed, then start increasing the accel.  This might help determine if your issue is jog-related, or a generally grumpy axis.

Unless a single strut is twisting the head, I don't think the gas strut(s) is the issue - I've got two on my mill and no similar issues.

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04 May 2024 21:35 #299753 by spumco
Replied by spumco on topic MPG choppy motion
BTW... what machine is this?  Does it have dovetail or box ways with gibs? Or linear bearings?

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