On Sat, 2010-08-07 at 12:07 -0500, Jon Elson wrote: > Stephen Wille Padnos wrote: > >> > >> > > Nothing has been removed, you would just use the stepgen in velocity > > mode, with a PID driving it (making FF1=1 should give you the equivalent > > of open-loop mode, plus or minus a step here and there). > > > > > I have to retract my previous erroneous statement, after some more > reading, Stephen is right (of course!) > By running stepgen in velocity mode and using PID, you convert your > stepper system into a true servo > system. > > > > The real problem is that screw mapping is meant for systems that have > > the screw between the feedback device and the table, but this machine > > isn't like that since the scale is actually on the table. You can't > > drive the PID very well with only scale feedback since it's too loosely > > coupled to the motors, but that's irrelevant since you can't really use > > steppers like servos anyway. > > > > > An excellent point, the "screw error compensation" would not be > correcting error on the LEADSCREW, it would be compensating for errors > in the linear encoder, which may not be necessary at all. > > Jon > Just to confuse the situation and possibly display my own ignorance;
It is possible to take position off the stepper for P and D and feed I the linear scale to get final settling? Dave > ------------------------------------------------------------------------------ > 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-developers mailing list > [email protected] > https://lists.sourceforge.net/lists/listinfo/emc-developers ------------------------------------------------------------------------------ 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-developers mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-developers
