Servo Tuning Advice

This is a wood working machine, so normal cutting feed speeds are a lot higher. Since this is going to mostly do 2.5-D Carving and engraving I am hoping that it won't matter to much.

Might there be any advantage to messing with the Traj period? My hal and ini files do not currently have any reference to it.

I made a stab to fix this error, please see here:

git.mah.priv.at/gitweb/emc2-dev.git/comm...276efd65f62684b77f57 :

motion: introduce motion.ferror-mode

by default (motion.ferror-mode == 0), ferror is computed based on the last commanded position, which is problematic with velocity-mode drives
if motion.ferror-mode == 1, ferror is calculated based on the new commanded position, and following error checks are postponed until after the new commanded position is calculated.

based on v2.5_branch . this is untested on a real machine.

please let me know if this makes a difference if you

setp motion.ferror-mode 1

- Michael

further to the aforementioned patch, here are two halscope shots taken off a stepper servo config - there is some indication that the patch does what we want:

scoping axis.0.error and pid.0.error

motion.ferror-mode set to 0:
static.mah.priv.at/public/motion-ferror-mode-0.jpg

note wildly diverging shapes

motion.ferror-mode set to 1:
static.mah.priv.at/public/motion-ferror-mode-1.jpg

pretty commensurate

- Michael

Could I get some brief instructions how to apply the patch?

I can't say for sure if I will test it, as the machine in question has been working acceptibly for a month or two, and I have s back log of work I need to catch up on.

I'll push this through the buildbot so we should have a package to test shortly

are you running 2.5 or master?

- Michael

I'm running 2.5

the ferror-mode 2.5-based RIP package is now online: buildbot.linuxcnc.org/dists/lucid/scratc...binary-i386/?C=M;O=D

I think it's this one: buildbot.linuxcnc.org/dists/lucid/scratc...ode~dafe9ea_i386.deb

- Michael

the ferror-mode patch has been merged into v2.5_branch.

- Michael

Now hopefuly someday I will find the time to try it out. It won't happen in the near future.