I've been in the process of setting up a new machine and have been
running into a "Following Error" while jogging and while running
g-code. After doing some experimentation with the FERROR and
MIN_FERROR variables, and reproducing the situation with the halscope
running, I think I have an understanding of the nature of the issue,
but am not sure what to do about it...

Details are as follows:

-Setting the MIN_FERROR=0.001 and FERROR=0.020 to make it easier to
reproduce the problem. It also occurs at FERROR=0.050 and
MIN_FERROR=0.005
-Setting jog velocity to 60ipm
-Setting MAX_VELOCITY=3, MAX_ACCELERATION=10

-Press the jog button for second, release the jog button for a second.
You can jog all day long just fine.
-Press the jog button for a second, release the jog button, and
quickly re-press the jog button, tirggers a "following error"
-Reproducing this while looking at the HAL scope, I have the hal-scope
triggering on f-errored, and probing velocity-fb, pos-cmd, pos-fb and
f-error
--In looking at the scope, I do infact see the f-error trace ramp up
above the 0.001 threshold, correctly triggering the following error
--In looking at the velocity-fb trace however, I see that the f-error
ramps up (or down) from zero during the deceleration phase of the
motter after the jog button has been released, then once the motor
velocity is at zero the f-error trace snaps back to zero. (This
doesn't seem quite right to me...)

My hypothesis is that if I press the jog button again during the
deceleration phase of a previous jog, and the f-error has accumulated,
it's exceeding the FERROR threshold and triggering the "following
error".

Also note, this does happen during executing of G-Code as well...

A little extra info:
-using EMC 2.3.4-pre
-using a Meas 4i65 card with hostmot2 for stepper motor controls, all
open loop for this testing setup


I'm not sure what to do about this?
-I can of course set the FERROR and MIN_FERROR higher, but it seems
like 0.005 is a reasonable number.
-Should I be setting up the HAL file in a different way?


Thoughts?


Thanks,
-Dave

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