On 7/3/24 15:28, Viesturs Lācis wrote:
Hello!
I need some guidance with getting the 8i20 drive running.
I have pins connected according to PCWs suggestion here:
https://forum.linuxcnc.org/27-driver-boards/45241-8i20#236124
BLDC component is loaded with "cfg=qi"
If I setp bldc.0.init to 1, motor does move a little and initdone also
goes to 1 making me think that it did see the encoder index. But I
cannot get the motor to turn (the belt is removed, it is disconnected
from machine) by jogging the axis, I cannot get it to move if I setp
pid.command to particular value.
I believe that I need to specify encoder-offset parameter, but I do
not understand how exactly encoder-offset value for BLDC component is
calculated.
What would be the recommended sequence to get the motor moving? For
example, first step - setp 8i20.angle and current pins to particular
values? Then connect them to bldc and setp bldc.0.value? I tried this,
does not work at the moment. Hopefully because of wrong
encoder-offset.
And then I hopefully will reach a point where PID will have to tuned.
What is current status of PID autotuning? I know that there is at-pid
(or something like that) component but I am not sure. Is it worth
trying?
Thanks in advance!
Viesturs
For that, the at-pid, my experience has not been good. Using the new
PID, I tuned the first 3 stepper driven axises of my go704 conversion
moderately well, but that rotary A servo oscillated at a fairly high
frequency and burned up the motor I was moving a chinese bs-1 with, and
did it in about a minutes elapsed time. I've since needed a much faster
rotary for another project, and used a 3 phase stepper/servo which
features a PID in the motor driver. Works perfectly driving a 5/1 worm
drive, spinning the A axis up to 500 rpm in perfect sync with X.
Ultimate accuracy is the backlash in the 5/1, less than .2 degrees.
Linuxcnc has no clue there is a PID in the motor controller. It Just
Works. And at reasonable speeds there is very little motor heating, so
much more power efficient.
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