Re: [CAD_CAM_EDM_DRO] AMAZING STUFF!

> From: "Tim Goldstein" <timg@...>
>
> Terry,
>
> I really don't think it was an original idea. EMC has had the ability to
> handle a closed loop stepper since the Feb 2000 release. In checking the
> archives of this list you can see that Matt Shaver and I discussed it on
> June 1, 1999 and in a wish list for EMC over the past summer Dan Mauch also
> said he would like to see closed loop steppers. Also, Alan up in Canada was
> working on an external PIC based solution a while ago. Finally, if you

check

> out
> http://www.microkinetics.com/motionc.htm
> And look at the OptiTracker card you will see "The OptiTracker can be used
> with MillMaster Pro for encoder feedback."
>
> My point is, just from the little I know it looks like a frequently
> discussed idea that has also previously been implemented by others and can
> not be consider piracy.

I can also add this link to a commercial product:

http://www.orientalmotor.com/automated/newproduct/index.htm

What I wonder is what will the control algorithm do when it senses that the
axis is lagging? In a servo system the amplifiers are commanded to increase
the motor speed. In a stepper system this would imply increasing the step
rate. If the motor has stalled, increasing the step rate won't do any good.
Steve Stallings stopped by today and we discussed this very issue. He felt
that lost steps were most often due to resonance problems and if you've just
lost a few steps because you went over a "resonance bump", then it may indeed
be possible to "catch up".

Matt