On Sat, 25 Apr 2020, David Berndt wrote:
Date: Sat, 25 Apr 2020 14:21:45 -0400
From: David Berndt <[email protected]>
To: "Enhanced Machine Controller (EMC)" <[email protected]>,
Peter C. Wallace <[email protected]>
Subject: Re: [Emc-users] Encoder reset on homing to index
Thanks for the feedback Peter.
I took the time to re-order my hal file (it's a bit of a disaster with all
the other non motion going-ons in there).
Here is the relevant start of m addf's
addf hm2_5i25.0.read servo-thread
addf motion-command-handler servo-thread
addf motion-controller servo-thread
addf pid.x.do-pid-calcs servo-thread
addf pid.y.do-pid-calcs servo-thread #rotary
addf pid.y2.do-pid-calcs servo-thread #linear
addf pid.z.do-pid-calcs servo-thread
addf pid.a.do-pid-calcs servo-thread
addf pid.s.do-pid-calcs servo-thread
addf sum2.3 servo-thread #pid.y.output +pid.y2.output ->
'y-output' -> hm2_5i25.0.7i77.0.1.analogout1
addf hm2_5i25.0.write servo-thread
I excluded all the stuff below which is are things like servo amp ready, amp
fault, coolant, spindle speed, spindle amp draw, f-error tracking, stuff that
happens in servo-thread but isn't exciting or relevant to motion in a
realtime way.
Yes, PID.y.index-enable, pid.y2.index-enable, hm2....encoder.03.index-enable,
and hm2...encoder.01.index-enable are all plumbed up and I show them going
TRUE during homing.
When I went out to the cold mill this AM and started fooling around I noticed
I was getting some following errors even in my previously configured
"acceptable" config which was driving axis.1.motor-pos-fb from the rotary
encoder still. Some hal-scoping around shows that maybe with the change I
need some re-tuning at higher speeds.
The need for retuning made me think that perhaps if the tuning was
questionable and that lead to a bit of runaway condition at higher speeds
then perhaps if I just decreased the max speed and tried assigning the linear
encoder pos fb to axis pos fb I might see an improvement.
So I did that, and it did. I'm now jogging back and forth at half the old max
speed and doing some basic G-code tests with the linear axis being
axis.1.motor-pos-fb. Which is nice because the GUI displays more enjoyable
numbers.
I'm not sure which change contributed to what, HAL reorder/cleanup, or
tuning.
My homing situation hasn't really changed. I still have to home twice to get
a completed homing cycle. I once got persistent runaway after homing (caught
quickly by f-error), but it wasn't self correcting, turning the machine on
again (f2) just led to another immediate runaway. Restarted linuxcnc to try
again and all was well. Interesting problems.
So as it stands now, homing (i have no idea what to actually try/change, it's
broken but also kind of fine...) , and more tuning (assuming it's not a fools
errand to change tuning with the addition of a linear scale...) are my next
steps.
-Dave
I suspect you will have to track down whats going on with halscope (triggered by
index-enable going low) and monitor the commanded position, feedback position
and PID output
On Sat, 25 Apr 2020 09:44:14 -0400, Peter C. Wallace <[email protected]> wrote:
On Sat, 25 Apr 2020, David Berndt wrote:
Date: Sat, 25 Apr 2020 03:23:20 -0400
From: David Berndt <[email protected]>
Reply-To: "Enhanced Machine Controller (EMC)"
<[email protected]>
To: "Enhanced Machine Controller (EMC)" <[email protected]>
Subject: Re: [Emc-users] Encoder reset on homing to index
After a few more hours tonight putzing around with this thing. Here's
where I'm at.
I've wired up the shared index. It completes both the encoder's
index-enable cycles. encoder.NRotary.position and encoder.nLinear.position
both reset to ~0. Home is also at 0 as is homeoffset, so once index is
found there should be no need for the axis to move. However it takes off
and gets caught by a fairly strict ferror.
If I then home it again the result seems to be close enough that the small
post-index-enable completion jump is within f-error. The axis moves a few
.001" and settles. I'm not sure what's causing this jump in the
first/second homing. Because of the ferror the first homing attempt does
not actually complete the homing cycle, ishomed is not set.
For the homing thing, I may setup a mux to turn off the
pid.yLinear.output. Maybe leave it off until everythings homed, or
everythings homed + some time, or some other benchmark. My machine spends
very little of it's time in an unhomed state and the control tends to stay
on 99% of the time so homing/rehoming isn't really much of a priority. Or
maybe abandon indexed homing.
It would also be nice to be able to feed pid.yLinear.feedback into
axis.1.motor-pos-fb. But that's a recipe for the axis taking off/tripping
ferror instantly. I'm not sure why, I can watch the pid.yRotary.feedback
and pidyLinear.feedback and they're quite close to each other. I think
this works fine pre-homed and breaks after homing but I'd have to re-run
that experiment to be sure. Seeing the machine @actual position being off
a few thou is really disconcerting. I can always press the @ to switch to
machine commanded, which is (hopefully, if the linear is more accurate)
much closer to reality.
-Dave
Is the index enable signal wired to both PID components in hal?
Also What is the thread order?
(it should be hardware_read, motion, PID, hardware_write)
Peter Wallace
Mesa Electronics
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Peter Wallace
Mesa Electronics
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