> > Here's a trace of the commanded velocity (after going > through limit3), > > encoder velocity (*60) and the lowpass output. > > > > http://www.franksworkshop.com.au/img_bin/Velocity.png > > > > The encoder scale is 12000; 12000 pulses representing 1 > revolution. > > The encoder velocity output is then multiplied by 60 to > give rpm. The > > graph shows acceleration to 20rpm and stop. > > Wow, that looks terrible. > > It looks like the command starts moving, then it takes a full > 200 ms before the encoder responds at all, and it immediately > overshoots by a factor of two. > > This is a servo-spindle, right? If you disable the PID and > PWM, and turn the spindle by hand, does it look any better? > I know it's hard to say what the real velocity should be in > that case, but this test would remove the PID tuning question.
Yep, servo spindle. I've really struggled to tune it. Initially I tried to tune it as a rotary axis, but I couldn't get it stiff. I didn't have any problems with X and Z, two smaller servos. Here's a scope of it turning by hand... http://www.franksworkshop.com.au/img_bin/Velocity2.png I'm not sure what the irregular pattern is from. Could it be motor cogging? > I did all my encoder velocity testing using the stepgen in > quadrature mode, and i'm pretty sure it looked much better. That was my original plan, to use a step generator to create a position signal that the spindle could follow. Is that possible? ------------------------------------------------------------------------------ The NEW KODAK i700 Series Scanners deliver under ANY circumstances! Your production scanning environment may not be a perfect world - but thanks to Kodak, there's a perfect scanner to get the job done! With the NEW KODAK i700 Series Scanner you'll get full speed at 300 dpi even with all image processing features enabled. http://p.sf.net/sfu/kodak-com _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
