On Wed, Aug 11, 2010 at 07:47:21AM -0700, dave wrote: > > Hi Chris, > Indeed that is exciting. Far better results than I would have expected. > I wonder if decreasing the servo cycle would decrease the following > error? Not that 0.0005 on acceleration is bad. That is about 13 counts > at the motor shaft if my math is correct. Maybe better is possible. > > Dave
Actually during the acceleration itself the following error is tiny. The little .0005 peaks are at the beginning and end of the acceleration phase, where the jerk is high. I believe this is fundamental in the mechanics and can't be improved without bounding jerk at a higher level. I should have saved a plot... Jeff E suggested I should measure real tach vs generated tach, to see the phase shift. He correctly points out that the shift may be less than a servo cycle, since my thread contains encoder read and then dac write, and the pins are hooked directly together, so the delay may be much less than the millisecond I thought was my starting point. I will try to scope those two things and measure the effect. Chris ------------------------------------------------------------------------------ This SF.net email is sponsored by Make an app they can't live without Enter the BlackBerry Developer Challenge http://p.sf.net/sfu/RIM-dev2dev _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
