On Tue, 2009-12-22 at 22:38 -0700, Dustin Monroe wrote: > Ok, I messed around with a 9v battery and adjusted the reference gain > and loop gain and got all three axis working without any following > errors. Now I have a new problem to solve, I am getting oscillation that > I cant get rid of and when I adjust the gain enough to solve it, i get > following errors. The oscillation doesn't seem bad except on the y axis. > the z and x feel almost like they are going back and forth between faces > on the encoder but the y has a pronounced vibration. Im thinking i will > need to rent an oscilloscope to fine tune the motors.
I must be missing something here as halscope normally does a great job of helping you tune servo axes. IIUC you adjusted gain on the amp to get max velocity and then tach gain so with the amp input shorted you get significant tendency to hold position. A battery box ... 9 V battery with a couple of lugs on it to attach leads to the amp and a DPDT switch to flip polarity can be a real help here. You can even use this with halscope to watch what happens with step inputs. Halmeter can be used to observe velocity. These tools are really good and not hard to use. If I can make them work anyone can. Get halscope running so you can observe following error. On some interfaces you may have to fiddle a bit .... using ddt ( in hal ) to get velocity and acceleration. Maybe scale following error at 100 mv to start with. Some interfaces have velocity and acceleration hal pins which makes it easy. You will adjust easily as you observe what happens. It IS comforting to know that your estop chain is in place and working before you tune. Just keep your body parts clear and not much bad can happen. Do short moves using jog or mdi and P first then work on FF1 and finally FF2. I've never had much luck getting I or D to improve following error from that point on. Realize that I'm talking about my machines and yours may respond quite differently. Once you get under 0.001 following error at max velocity then the real work begins. Making slight adjustments in parameters attempting to reduce the following error. Unfortunately, servo tuning is as much art as science. Someday we will have autotune tools that take out most of the pain. You are making progress it just takes time. Keep asking questions, there is lots of good help on this list. Good Luck. Dave > > ------------------------------------------------------------------------------ > This SF.Net email is sponsored by the Verizon Developer Community > Take advantage of Verizon's best-in-class app development support > A streamlined, 14 day to market process makes app distribution fast and easy > Join now and get one step closer to millions of Verizon customers > http://p.sf.net/sfu/verizon-dev2dev > _______________________________________________ > Emc-users mailing list > Emc-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-users ------------------------------------------------------------------------------ This SF.Net email is sponsored by the Verizon Developer Community Take advantage of Verizon's best-in-class app development support A streamlined, 14 day to market process makes app distribution fast and easy Join now and get one step closer to millions of Verizon customers http://p.sf.net/sfu/verizon-dev2dev _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
