Servo Tuning FF
Thanx
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They are set in the HAL file, in exactly the same was as the PGain and IGain.Please tell me just where these 'FF' values are set and how to get there. I am using Mesa 7i43 (small) with 7i33.
The actual values are probably read into the HAL file from the INI file, but putting them in the INI file will achieve nothing without a reference and a setp statement in the INI file.
You probably need to understand a bit about HAL pins and parameters.
linuxcnc.org/docview/2.5/html/hal/basic_hal.html
The pins and parameters of the PID component are described here:
linuxcnc.org/docview/2.5/html/man/man9/pid.9.html
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verry good thread ...
to make SIMulated and optimicing my PID i have on my PC (office) the servo_sim.ini ...
what can i do to work simulated with the PIDs ? actuall i becomes ONLY the f.error joint 0 following error .
(he goes LINEAR from to to max-ferror ..)
i am stupid ? and the SIM its NOT for simulated a servo ? *g*
thanks for help.
PS: what its the POINT - i found NO samples for optimicing the PID and Co ?
PStart = 0
Pn = 0.5
Pmax = 5
.... then combine with the <I> <D> <F1> <F2> ? automaticly with ala pyhton ?
PPs: i goes to update the "office-pc" with the:
deb buildbot.linuxcnc.org/ lucid v2.5_branch-sim
deb-src buildbot.linuxcnc.org/ lucid v2.5_branch-sim
i hope this its the right way
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No, sim is simulated real time, not simulated servo.and the SIM its NOT for simulated a servo ? *g*
MANY years ago, the old EMC had a simulated motor/machine,
but it was not terribly realistic. Unless you make detailed
measurements to the motors electrical and mechanical
characteristics and all the springiness, friction and masses
of the machine, simulation will be totally pointless, anyway.
Trying to develop tuning parameters on a simulation is
only of benefit for NASA, where you can't operate the
device in its natural environment.
Jon
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Following is a copy of my INI
any help would be greatly apprecieated.
Thanks
Rick
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We now have a Servo Tuning area... I'd move this post but seems like you can't move a post that is older than the category.
John
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So _expect_ a runaway and verify that you can power things down or disable the servo quickly before starting. As John says , once you have feedback working and can jog things, then reconnect the motors to the mechanics for tuning.
I would also add that you should verify the drive enable circuitry before starting.
you want a ferror to instantly disable the drives. You will need to have larger values of FERROR and MIN_FERROR as you start to tune
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Thanks guys
Rick
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When I tested my CHNC I made a simple box with a couple of switches, one for enable, and one for jog and the jog input was from a variable voltage power supply so I set it at like 1/10 of a volt just to make sure jog plus and jog minus went the correct way. I did find out that with the drive enabled and no velocity input there was some drift... YIKES. So the moral of that story is don't jumper out the enable from the rear of the machine unless you can see the axis.
John
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The very first thing is to verify that the position feedback works, is scaled properly and has the proper direction (prehaps by hand moving the motor shafts with the drives disabled and watching the Axis DRO)
to check feedback direction, you first determine which voltage input polarity drives the axis which direction This can be done with a custom hal file and manually setp-ing the analog output voltage or simply with a 1.5v battery connected to the drives analog input pins
Once you know which input polarity drives the axis in which direction write this down
Now you disable the servo drives(remove power), set a large FERROR and MIN_FERROR and start LinuxCNC with PID setup with a small P and all other terms = 0
Now when you hand crank the motor shaft the analog output voltage should change such that it would oppose the motion. That is if a positive voltage makes the axis go right, moving the axis by hand to the right should generate a negative voltage on the analog out pins, and moving to the left of the starting point should generate a positive voltage. If these are reversed you will need to reverse the PID output polarity
The other thing to check here is that the analog voltage varies smoothly from -10V to +10V as you rotare the motor shaft
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