Joint 0 following error. Error on axis 0, command number X

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12 Dec 2017 14:17 #102997 by AndrewHsasku
I am trying to develop my configuration.
At the moment I am having problem with error
Joint 0 following error
printed in linuxCNC and
Error on axis 0, command number X
printed in terminal.
No idea what I miss in .ini/.hal/.c. Projects uses trivkins and pid. FERROR for each axis is set to 1. LinuxCNC is installed on VirtualBox. When starting I also receive an error
Unexpected realtime delay on task 1
. Latency is nearly 1s (nothing strange when it is installed on virtual machine).
What would be a reason of this error: something missed or just latency?

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12 Dec 2017 14:34 #102999 by BigJohnT
You can't run LinuxCNC from a Virtual Box as it's not real time.

JT

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12 Dec 2017 15:37 #103004 by PCW
If you are just testing the driver and don't care about motion behaviour you can loop back the
commanded position to the feedback position and avoid following error faults

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12 Dec 2017 16:26 #103008 by AndrewHsasku
Looping feedback and position changes nothing.
Thats part of my hal:
# THREADS
# ################################################

addf driver.read servo-thread

addf motion-command-handler servo-thread
addf motion-controller servo-thread

addf x-pid.do-pid-calcs servo-thread
addf y-pid.do-pid-calcs servo-thread
addf z-pid.do-pid-calcs servo-thread
addf a-pid.do-pid-calcs servo-thread

addf driver.write servo-thread

# PID
# ################################################

setp z-pid.Pgain 1.0
setp z-pid.Igain 0.0
setp z-pid.Dgain 0.0
setp z-pid.FF0 0.0
setp z-pid.FF1 1.0
setp z-pid.FF2 0.0
setp z-pid.deadband 0.01
setp z-pid.maxoutput 200.0

net z-enable	axis.2.amp-enable-out				=> z-pid.enable driver.axis_z.enable
net z-pos-cmd	axis.2.motor-pos-cmd				=> z-pid.command
net z-pos-fb	driver.axis_z.position	=> z-pid.feedback	axis.2.motor-pos-fb
net z-vel-cmd	z-pid.output						=> driver.axis_z.velocity

net z-fault		driver.axis_z.fault		=> axis.2.amp-fault-in

My functions write and read do not execute

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12 Dec 2017 16:50 #103012 by PCW

net z-pos-cmd axis.2.motor-pos-cmd => z-pid.command
net z-pos-fb driver.axis_z.position => z-pid.feedback axis.2.motor-pos-fb



You did not loop back command to position, that would be done something like this:

net zpos axis.2.motor-pos-fb axis.2.motor-pos-cmd

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12 Dec 2017 16:59 #103014 by AndrewHsasku
Yeah, pasted one is my original code before changes. I have tried suggested changes rather like below and it didn't helped
net z-pos-cmd	axis.2.motor-pos-cmd				=> z-pid.command
net z-vel-cmd	z-pid.output						=> z-pid.feedback	axis.2.motor-pos-fb

Anyway just feed backing this way will just omit my driver.
Inside driver code, in read function, just for current tests, there is cloning data from driver.axis_z.velocity to driver.axis_z.position. However as far, read function do not execute.

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12 Dec 2017 17:15 #103016 by PCW
if you want to avoid the fault and still be able to run without looping back command to feedback, you could always set ferror
and min_ferror to 1e30 or some such

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12 Dec 2017 19:07 - 12 Dec 2017 19:09 #103028 by AndrewHsasku
ferror and min_ferror doesn't help.
Commenting my code and using just:
net x-pos-cmd	axis.0.motor-pos-cmd	=> axis.0.motor-pos-fb
works, but it skips my driver. Adding PID crashes again:
net x-pos-cmd	axis.0.motor-pos-cmd	=> x-pid.command x-pid.feedback
net x-vel-cmd	x-pid.output	=> axis.0.motor-pos-fb

Do I miss sth in PID conf?
I also can't execute anything from driver. Read and write functions don't execute. rtapi_print_msg doesn't print anything. Values changed on rtapi_app_main are not changed in Hal Meter
Last edit: 12 Dec 2017 19:09 by AndrewHsasku.

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