For a little information on tuning see this http://support.motioneng.com/Downloads-Notes/Tuning/default.htm And on the right near the bottom http://support.motioneng.com/Utilities/Bode/default.htm
Body Plot would be great to have. How about an FFT too? Noel R. 'Roguish" -----Original Message----- From: Gene Heskett [mailto:[email protected]] Sent: Sunday, December 09, 2012 4:40 PM To: EMC developers Subject: [Emc-developers] PID tuning, Zeigler-Nichols method Greetings; I haven't tried this method yet, primarily because when it says its supposed to oscillate, I would assume it is meaning a runaway, and will be limited by the rail to rail range of the control at pid.N.out. I can't make Pgain cause more than about a 10% of that range cyclic wibble, not near enough to hear it with the spindle at say 6 rps commanded. At least at Pgains up to 150 or so, with FF0 = 100, FF1 = 20 and FF2 = 10. Should I be able to induce a rail to rail oscillation with Pgain? Also, the sheet I've printed <http:www.linuxcnc.org/2.5/html/motion/pid_tuning> for guidance make no mention of the FF0, FF1 & FF2, whereas the man 9 pid does. But it does make this statement in the man page that I just now noticed: pid.N.feedback-deriv float in The derivative of the actual (feedback) value for the control loop. If no signal is connected then the derivative will be estimated numerically. When the feedback is from a quantized position source (e.g., encoder feedback position), behavior of the D term can be improved by using a better velocity estimate here, such as the velocity output of encoder(9) or hostmot2(9). I hadn't noticed this before, so encoder.0.velocity only feeds the pid.N.feedback pin. It sounds as if I should feed both pins with encoder.0.velocity. Done, but not tested yet. Comments anyone? Thanks. Cheers, Gene -- "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) My web page: <http://coyoteden.dyndns-free.com:85/gene> is up! Fairy Tale, n.: A horror story to prepare children for the newspapers. I was taught to respect my elders, but its getting harder and harder to find any... ---------------------------------------------------------------------------- -- LogMeIn Rescue: Anywhere, Anytime Remote support for IT. Free Trial Remotely access PCs and mobile devices and provide instant support Improve your efficiency, and focus on delivering more value-add services Discover what IT Professionals Know. Rescue delivers http://p.sf.net/sfu/logmein_12329d2d _______________________________________________ Emc-developers mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-developers ------------------------------------------------------------------------------ LogMeIn Rescue: Anywhere, Anytime Remote support for IT. Free Trial Remotely access PCs and mobile devices and provide instant support Improve your efficiency, and focus on delivering more value-add services Discover what IT Professionals Know. Rescue delivers http://p.sf.net/sfu/logmein_12329d2d _______________________________________________ Emc-developers mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-developers
