John Kasunich <jmkasun...@...> writes:
> > No, for two reasons: > > 1) A lowpass filter will not solve PID of instability - if anything it > will make it worse since it introduces a lag. > > 2) ilowpass is an _integer_ filter, it can't be used for floating point > signals (which include the command, feedback, and output of PID loops). > > The correct solution is to tune your PID loops (using D and deadband as > needed) until they are stable. You must use halscope to view the > resulting waveforms and decide what to adjust. > > Once you have the axes tuned as well as possible, halscope will tell you > the maximum error you have during a rapid. Assuming that is acceptable, > you set the following error a bit higher so it doesn't trip. > > Regards, > > John Kasunich OK, got that. Since I have not had the opportunity to witness other EMC2 servo conversions, I am guessing / interpreting what you refer to as "stable". I assume you mean that the mid frequency moaning/buzzing goes away. My mill will quiet down after sitting at rest for about 30 seconds. I can see this on halscope in the form of a sawtooth trace that hovers close to zero. Perhaps my deadband and D term can be adjusted so that it quiets down in a few seconds. But then, from experience I find that following error goes up. Question: If I tune the PID for the lowest following error while making the buzzing sound (sawtooth trace) go away, (and set MIN_FERROR & FERROR accordingly), but then if I am not happy with the accuracy of my cuts at normal feedrates (20-70 ipm), will I then need to change to higher count encoders? (Currently Renco 500 line / 2000 ppr) Thanks to all for helping me here... Tom ~ Kasuga (large Shizuoka type) EMC2 conversion: Mesa 5i20/7i33 - brush servos - Advanced Motion PWM brush amps - Renco RCML15 500 line encoders: 2000 ppr in quadrature. All the the encoders mounted directly on the back of the servos on the rotor/tachometer shaft. ------------------------------------------------------------------------------ This SF.net email is sponsored by: High Quality Requirements in a Collaborative Environment. Download a free trial of Rational Requirements Composer Now! http://p.sf.net/sfu/www-ibm-com _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
