On Tuesday 11 December 2012 13:25:35 Jon Elson did opine: > Gene Heskett wrote: > > On Monday 10 December 2012 23:07:29 noel did opine: > >> For a little information on tuning see this > >> http://support.motioneng.com/Downloads-Notes/Tuning/default.htm > > Not sure if any of this is of any use unless you have a drive from > MotionEngineering. > > Jon Well, what I came away with is that while they seem to have a circuit for PID, and another for PIV, our 'PID' with some name changes on the dials, is a bit of a combination of both. In my case, it seems as if I am getting stiffer results by using the .FFx pins instead of the Igain and Dgain. But I am not finished with its configuration yet either, because it also seems that somewhere, there is very noticeable non-linearity. The creep speeds feedback is negative, turns positive at about 5 rps and then goes back negative at speeds above 50% of wide open.
What comes out of axis, if you have a fine enough step size, is a minimum of .01677777 just by clicking the fwd button, but a click on the + button adds "about" 1 to that for every click. By the time I add min-dc etc to get it to creep at about .3 rps for that first click, it seems like the static friction component is enormous. I am not done diddling with this, but atm its working better by using the FFx, where x is not 0, in fairly large quantities, than I can get with P,I,D alone. This after all, is not a position servo, but a velocity servo. And I am getting better results I think, by treating it more like a PIV, than a PID. IMO its nice to have both sets of knobs available. FF0 is currently set at 100 for near zeroing the PID.error output, although that is somewhat dependent on Pgain, currently about 100. In fact, I am thinking of writing a gcode loop to run forever to square wave the requested velocity from say 1 to 10, at 3 secs up 5 seconds down intervals, triggering halscope on that, just so I can get some waveforms that I see in the discussions on tuning PID and PIV stuff. There is a lowpass with a long time constant between the requested speed, and pid.command in, else even a 100 rpm step up request sent without ramping it will clear the fuse at about 90 cents a pop. Even running the loop will probably fatigue the fuse and clear it if I try to make it too fast in the requested path. I'll have to do that before I think I will arrive at any better settings than I have right now. 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! Organic chemistry is the chemistry of carbon compounds. Biochemistry is the study of carbon compounds that crawl. -- Mike Adams 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
