My unqualified thoughts :-) I've seen these spikes a lot whilst tuning the servos on my mill. I think they are a characteristic of FF1 tuning. It is very tempting to tweek FF1 and watch the f-error generally tumble, only to be left with these spikes. Note from Screenshot4 that the spikes occur at the transition from acceleration to constant velocity or vice versa. When there is a reversal of the contribution made by FF1, it is almost instantaneous and it simply isn't possible for the the servo to respond fast enough. I found by improving the tuning at the amp and then EMC2's P (I don't find I and D help much if at all), resulted in using much less FF1 (the spike is always present, though much reduced). Having said all that, I suspect these spikes have little or no effect on the quality/accuracy of the machined part as the machine simply can't respond fast enough (a point I've been unable to verify as sadly my machine is down at the moment).
Regards, Richard > http://www.mpm1.com:8080/machines/Screenshot1.png > http://www.mpm1.com:8080/machines/Screenshot2.png > http://www.mpm1.com:8080/machines/Screenshot3.png > http://www.mpm1.com:8080/machines/Screenshot4.png > > The pictures show some of the progression during tuning. Number 4 is the > final result. My questions have been trying to figure out why the traces > have the spikes like they do. ------------------------------------------------------------------------------ Beautiful is writing same markup. Internet Explorer 9 supports standards for HTML5, CSS3, SVG 1.1, ECMAScript5, and DOM L2 & L3. Spend less time writing and rewriting code and more time creating great experiences on the web. Be a part of the beta today. http://p.sf.net/sfu/beautyoftheweb _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
