Axis Creep

Have you considered the possibility that it could be a noise issue on your MPG encoder inputs?

Monitor the counts for the MPG encoder(s) while you are experiencing the drift problem. You should look at their A&B input pins with Halscope, (looking for signal noise).

Hi Peter.

Below is an extract from the HAL file referring to MPG movement.

To help identify, the MPG is connected to a 7i84 set to encoder mode, it is the first of three 7i84's and is thus addressed 0.
Namely hm2_5i24.0.7i84.0.0..........

I seem to recall a section was included to smooth jogging motion but as I glance over the HAL file it is not apparent to me.

Complete HAL and INI files attached a few posts up.

Thanks,
Marty.


# ---jogwheel signals to mesa encoder - shared MPG---

net joint-selected-count <= hm2_5i24.0.7i84.0.0.enc0.count

# ---mpg signals---

# for axis x MPG
setp axis.0.jog-vel-mode 0
net selected-jog-incr => axis.0.jog-scale
net joint-select-a => axis.0.jog-enable
net joint-selected-count => axis.0.jog-counts

# for axis y MPG
setp axis.1.jog-vel-mode 0
net selected-jog-incr => axis.1.jog-scale
net joint-select-b => axis.1.jog-enable
net joint-selected-count => axis.1.jog-counts

# for axis z MPG
setp axis.2.jog-vel-mode 0
net selected-jog-incr => axis.2.jog-scale
net joint-select-c => axis.2.jog-enable
net joint-selected-count => axis.2.jog-counts

# for axis 4th MPG
setp axis.3.jog-vel-mode 0
net selected-jog-incr => axis.3.jog-scale
net joint-select-d => axis.3.jog-enable
net joint-selected-count => axis.3.jog-counts


# connect selectable mpg jog increments

net jog-incr-a => jogincr.sel0
net jog-incr-b => jogincr.sel1
net jog-incr-c => jogincr.sel2
#net jog-incr-d => jogincr.sel3
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 0.001000
setp jogincr.in01 0.001000
setp jogincr.in02 0.010000
setp jogincr.in03 0.001000
setp jogincr.in04 0.100000
setp jogincr.in05 0.010000
setp jogincr.in06 0.050000
setp jogincr.in07 0.100000
setp jogincr.in08 0.125000
setp jogincr.in09 0.125000
setp jogincr.in10 0.125000
setp jogincr.in11 0.125000
setp jogincr.in12 0.125000
setp jogincr.in13 0.125000
setp jogincr.in14 0.125000
setp jogincr.in15 0.125000

I think what Todd was suggesting is that you monitor hm2_5i24.0.7i84.0.0.enc0.count
(say with halmeter) to see if its possibly creeping due to a noise issue of some kind

Thanks yes. I'll do that tomorrow and report back.
I had the machine running all day and after an initial jog is finished and the drift takes place over the following 3 minutes, after that time the Z axis has no further movement after checking over the course of the following hour.
Then jog again, 3 minutes of slow drift again (in the direction of the jog) then static again at that point onwards (again, checking periodically over the course of an hour).
It was this behavior (i.e. static after the initial creep) that made me lean towards a few residual mpg pulses (encoder filtering?).
As suggested I'll check with HAL meter and let you know.
Thanks again!
Marty.