Sorry, Viesturs, that was a language glitch of mine. "Servo" is used in German as a general classification for anything moving with power assistance, above all in the motor vehicle sector, e. g. Servolenkung (power steering) or Servobremse (power brake) as well as in "Ruderservo" (RC model actuator) etc. Only as a specific technical term it is used in the field of control technology as a name for a feedback controlled continous motor drive. At this moment, regarding my own (stepper) gear I didn't even think of someone else using servomotors for moving machine elements.
Peter Viesturs La-cis schrieb: > Peter, just as the name of threads says, I am trying to tune servo > motors, not steppers :) > I just checked - the supply voltage is 27,9 VDC, because 7i39 drives > have 28 VDC limit. > > Ohh, and there is update: > The motor that yesterday worked fine at 4000 mm/min, today is not > working fine at that speed - it also stalls and starts oscillating at > relatively high frequency... Just as the name of thread says - I have > no idea wtf is wrong with this machine. > > I just remembered one thing that I had not mentioned, but which > probably might make a difference - Keling servos are equipped with CUI > AMT102 encoders. I recall that Jon Elson wrote some time ago that > these encoders have a lag during change of acceleration, so I looked > at that thread again. > > Is there anything I can do to confirm, if the encoders are the real > problem of the instability of the feedback loop. > > Viesturs > > 2012/1/29 Peter Blodow <p.blo...@dreki.de>: > >> Viesturs, >> regardless of possible tuning questions, if I recall right, you are >> using a 24 volts supply for the stepper amplifiers. This seems a little >> low to me as I was using 90 volts on my dual Parker Hannifing >> amplifier/driver. I had stepper motors attached to the two slides of my >> lathe and never experienced any oscillations. The amps came to a maximum >> of about 30 kHz, but as the steppers were coupled directly to the >> spindles (no gears) they reached the spindle ends before frequency could >> grow any higher anyway. The motors have about 85 mm diameter and are >> labelled for 3 volts so there is a lot of momentum in this drive. When a >> slide accidentally hit the physical end of a way (no limit switches >> there), it usually turned off the 3 mm steel dowel I am using in the >> couplings. >> >> I think at your 24 volt level and the resulting maximum motor forces or >> angular momenta, you are working near the physical resonance limit where >> anything can happen. Try a higher power supply voltage in any case. >> >> Peter >> >> Viesturs La-cis schrieb: >> >>> 2012/1/28 Peter C. Wallace <p...@mesanet.com>: >>> >>> >>>> OK so commutation is ok, but somthing is funny here. You said it oscillated >>>> even with a P of 1 and all else 0. Did it not oscillate with a P of 3? >>>> what is the difference between the setup now and when it oscillates? >>>> >>>> >>>> >>> I will try to explain: >>> I am trying to tune 2 motors simultaneously, because it is a gantry machine. >>> So what I did few minutes ago: >>> For both motors: all PID parameters set to 0 >>> P = 3 >>> I tried to jog the gantry at slow speed. >>> At 240 mm/min it is smooth, at 480 mm/min still smooth, but at 676 >>> mm/min there are spots, when one of motors stalls and oscillates in >>> small amount at high frequency. I suspect that the stalling is due to >>> some uneven load to motor, when moving forward. >>> Anyway, I d not know, how to overcome such stalls and subsequent >>> oscillation. >>> Hitting F2 to disable and re-enable motion stops oscillation and I can >>> jog forward. Until one of motors stalls and starts vibrating again. >>> >>> I do understand that final settings for both gantry motors might >>> differ, I just think that in the beginning they could be tuned >>> together as both of them are stalling now. >>> >>> Viesturs >>> >>> ------------------------------------------------------------------------------ >>> Try before you buy = See our experts in action! >>> The most comprehensive online learning library for Microsoft developers >>> is just $99.99! Visual Studio, SharePoint, SQL - plus HTML5, CSS3, MVC3, >>> Metro Style Apps, more. 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