Servo tuning / debugging help - clarification of context….

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5 years 8 months ago #198135 by db1981
Then your axis scaling is wrong, with this numbers i get 83.33mm/s.
the max_velocity from each axis should be ~ the theoretical mechanical speed at max Output. (you can correct this with ff1, but normaly in an velocity controll loop this should be 1.0. )

So, if you only want 2100mm/min then [Axis]max velocity should be 35.0 and [Axis] Outputscale = 4.2 (if your servo drive is set to 10V=2000rpm), ff1 = 1.0.

Then Limit the Pid output to near your output scale for example +5 / -5 so the controller would never output more than 1000rpm. 5V becaus you will need some
headroom for the controller to correct moves at max speed.

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5 years 8 months ago - 5 years 8 months ago #198182 by Jaro
Thanks DB.
please, can you explain me how to calculate max velocity and outputscale?
servo has 2000rpm/10V
gear ratio is 1:2 so i get 1000rpm/10V behind the transfer
balscrew pitch is 5mm

1000 x 5 / 60 = 83.33mm/sec (this is maximal theoretical velocity)
meantime i corrected MAX-VELOCITY = 16.6 (last ini file )
but how this everything I can calculate on OUTPUT_SCALE, OUTPUT_MIN_LIMIT , OUTPUT_MAX_LIMIT and MAX_OUTPUT?
please, try to explane. what is necessy to stet or change?

when I set servo 800rpm/10V (i think it is possible configure driver for that)
and set
MAX_LINEAR_VELOCITY = 33.33
(TRAJ)
MAX_VELOCITY = 33.33
(AXIS X,AXIS Y,AXIS Z)
MAX_OUTPUT = 10
OUTPUT_SCALE = 9
OUTPUT_MIN_LIMIT = -10
OUTPUT_MAX_LIMIT = 10
is this correct?

thanks
Jaro
Last edit: 5 years 8 months ago by Jaro.

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5 years 8 months ago - 5 years 8 months ago #198183 by Jaro
thank you very much PCW and TODD.
today I manualy comment: net x-vel-cmd => pid.x.command-deriv and
uncommented #setp pid.x.error-previous-target true.
now I can use FF1 and FF2 for F-error tuning with halscope.
thanks again
Jaro
Last edit: 5 years 8 months ago by Jaro.

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