8i20 brushless servo drive output amps
24 Apr 2014 19:21 #46286
by andypugh
Is the PID output still limited to 1?
The code in the version of the driver you are using is as follows:
251 norm_current = *hal->pin.hm2_current
252 * hal->param.hm2_max_current
253 / hal->param.hm2_nv_max_current
254 * i_const;
So, the "current" pin value is multiplied by the max-current parameter and then divided by the value from the nvram (which you have changed).
In the hal file you posted earlier the line
#setp hm2_5i25.0.8i20.0.0.max_current 15
was commented out, so the max_current defaults to nv_max_current.
So, actually, PCW was correct that the net effect is a current command that scales from 0 to 1.
Looking at the code in 2.6 / master you will need to be aware that the input value becomes actual amps in that version, and all the pin names change.
wiki.linuxcnc.org/cgi-bin/wiki.pl?UpdatingTo2.6
Sorry about that.
Replied by andypugh on topic 8i20 brushless servo drive output amps
I have it set to 15 amps and it made a huge difference. The motor has lots of torque and is practically unstoppable with my hands.
Is the PID output still limited to 1?
The code in the version of the driver you are using is as follows:
251 norm_current = *hal->pin.hm2_current
252 * hal->param.hm2_max_current
253 / hal->param.hm2_nv_max_current
254 * i_const;
So, the "current" pin value is multiplied by the max-current parameter and then divided by the value from the nvram (which you have changed).
In the hal file you posted earlier the line
#setp hm2_5i25.0.8i20.0.0.max_current 15
was commented out, so the max_current defaults to nv_max_current.
So, actually, PCW was correct that the net effect is a current command that scales from 0 to 1.
Looking at the code in 2.6 / master you will need to be aware that the input value becomes actual amps in that version, and all the pin names change.
wiki.linuxcnc.org/cgi-bin/wiki.pl?UpdatingTo2.6
Sorry about that.
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- johns00056
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25 Apr 2014 01:09 #46290
by johns00056
Replied by johns00056 on topic 8i20 brushless servo drive output amps
The motor is running great today. The moving parts weigh more than 2 tons. I have the maximum speed set to 100 inches per minute (that seems plenty fast for me) but it will go faster with no problem.
I ran it for a little while with the min following error set to .0001 inch and .020 max following error (which was my goal) and it was able to do it. ( except when I spun the MPG jog wheel really fast on .010 per increment setting)
#setp hm2_5i25.0.8i20.0.0.max_current 15 --- I commented out this line because it had no effect.
The PID output does not appear to go above 1.
Thanks for all your help. I am sure that I will have many more questions before this project is complete.
I ran it for a little while with the min following error set to .0001 inch and .020 max following error (which was my goal) and it was able to do it. ( except when I spun the MPG jog wheel really fast on .010 per increment setting)
#setp hm2_5i25.0.8i20.0.0.max_current 15 --- I commented out this line because it had no effect.
The PID output does not appear to go above 1.
Thanks for all your help. I am sure that I will have many more questions before this project is complete.
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25 Apr 2014 06:52 #46294
by andypugh
I think that that is because you have limited it to 1 in the HAL.
If you upgrade to 2.6 you will have to change the PID limit to the max current in amps, and probably re-tune a bit, due to the changes I mentioned earlier.
Replied by andypugh on topic 8i20 brushless servo drive output amps
The PID output does not appear to go above 1.
I think that that is because you have limited it to 1 in the HAL.
If you upgrade to 2.6 you will have to change the PID limit to the max current in amps, and probably re-tune a bit, due to the changes I mentioned earlier.
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