On Mon, 05 Oct 2009 12:42 -0400, "Eric H. Johnson" <ejohn...@camalytics.com> wrote: > Hi all, > > (For Peter) I think I found the main problem with tuning the X and Y > axes. I > used the registry values of the old system to set the initial parameters > for > EMC, and goofed on interpreting the accel parameters. In the Galil > world, > these are in encoder counts / sec^2 rather than units per sec^2. So > MAX_ACCELERATION was set much too high. After backing it off, I am > getting > much better results for the X and Y axis. > > My question now is about angular axes. While the X and Y axes have on > the > order of 5000 counts per inch, the rotational axis only has 51.1 counts > per degree (18400 per revolution) If I use 18400 for my INPUT_SCALE, I can > tune the axis rather easily. Of course in this case if I issue: > G1 A1 F50 It will turn 360 degrees rather than 1 degree. > > If I set INPUT_SCALE to 51.1 and adjust MAX_VELOCITY and MAX_ACCELERATION > proportionately, tuning again becomes much more difficult, ISTM due to > the granularity of the scaling.
Write down the PID gains that work when the scale is 18400. Then, since you are dividing the scale by 360 to get 51.1, you should be able to also divide the gains by 360, and the resulting PID results should be identical. Take the old gains, divide by 360, and try them as a starting point for tuning. Regards, John Kasunich -- John Kasunich jmkasun...@fastmail.fm ------------------------------------------------------------------------------ Come build with us! The BlackBerry® Developer Conference in SF, CA is the only developer event you need to attend this year. Jumpstart your developing skills, take BlackBerry mobile applications to market and stay ahead of the curve. Join us from November 9-12, 2009. Register now! http://p.sf.net/sfu/devconf _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
