On Mon, 26 Nov 2012, Jon Elson wrote: > craig wrote: >> >> What useful information can be extracted from sensing stepper voltage >> and current responses? >> >> > Mariss Freimanis of Gecko did quite a bit of work on this a while ago, > called the > "unstallable stepper", I think. There should still be some info on the > Geckodrives > web site about it. The problem, of course, is if one motor slows down > to prevent > a stall, all the other motors need to also slow down by the same amount, or > you still make a mess of the part. I think this is where Mariss fell > down, as > he didn't have a sensible way for the drive to report what it was doing > back to > a CNC control with software-generated steps out the parallel port. >> Are there useful differences in the waveforms for missing steps? nearly >> missing steps? >> > Once you've missed a step, all is lost as the stall is in progress. > What Mariss was doing > was measuring the phase angle between current and voltage, and he could > keep the > stator pole just less than 90 degrees ahead of the rotor pole, to > develop maximum > torque. When the phase angle exceeded this, you had to back off or move > into > the stall territory. >
with an encoder on the motor shaft and a linear encoder on the axis gantry could linuxcnc be configured to detect a stall maybe as simple as a loose motor connector ------------------------------------------------------------------------------ LogMeIn Rescue: Anywhere, Anytime Remote support for IT. Free Trial Remotely access PCs and mobile devices and provide instant support Improve your efficiency, and focus on delivering more value-add services Discover what IT Professionals Know. Rescue delivers http://p.sf.net/sfu/logmein_12329d2d _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
