> On Wed, May 06, 2009 at 04:37:07PM +1000, Frank Tkalcevic wrote: > > I've just configured my first emc project, a 9x20 lathe > conversion. I'm > > using a large servo for the spindle - I'm hoping to be able > to use it as a > > 4th axis for some light engraving down the track. > > > > My problem - I've set up the servo for the spindle, but > like a servo, it > > responds imediately to change requests. I haven't put a > chuck on it yet, > > but it I'm sure it will break the belt when it tries to > stop from 1000rpm to > > 0, instantly. > > > > Any ideas on how I can soft start and stop it? > > Send the commanded spindle speed through a limiter before pid, so that > the pid 'command' value varies slowly. > > "limit2", "limit3", and "lowpass" are three built-in components that > limit a signal: > > "limit2" limits the range and first derivative of a signal. > > "limit3" limits the range, first and second derivatives of a signal. > > "lowpass" uses an exponentially-weighted moving average to track an > input signal.
Thanks. I used "limit3" and it produced nice looking s-curves. Start up was fine, but the stop was a bit painful. I use the motion.enable signal to enable the pid and pwgen on my 5i20. When the spindle is stopped, the motor would halt. I had to use a combination of "near", "or2", and "not" to monitor the output of "limit3" and not disable the drive until the commanded speed was near 0. Thanks, Frank ------------------------------------------------------------------------------ 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
