Re: [CAD_CAM_EDM_DRO] Re: Re: Re: GeckoDrives.. Can anyone Help?

Gentlemen,

Could we step/direction guys bridge this gap with Marris' help? Let me make
a suggestion:

Could we not make a hardware (IC based) adapter which included an enocder
driven counter, a hardware comparator, and another hardware counter driven
by our step /direction signals, and then a D/A converter driven by the
hardware comparator, which would then drive one of Marris' upcoming +_
servo amps? Would we not be thus able to provide the P, and he provide the
I, D, and the actual amplifier to drive the servo motor?

I have already emailed Marris with this idea. I suppose I should have put
the whole thing on this forum rather than bother him, but after I emailed
him, I thought others might have some good ideas related to this.

It does not seem as though the hardware for the P of the PID would be much
to come up with, and maybe it would provide another compromise helping us to
get closer to the true velocity control desired in some applications.

I probably do not see the big picture, but I thought I'd ask.

Tom Eldredge,

----- Original Message -----
From: Jon Elson <jmelson@...>
To: <CAD_CAM_EDM_DRO@yahoogroups.com>
Sent: Thursday, March 15, 2001 2:25 PM
Subject: Re: [CAD_CAM_EDM_DRO] Re: Re: Re: GeckoDrives.. Can anyone Help?


>
>
> Ray wrote:
>
> >
> > Jon is speaking about the electronic packages needed to drive the
> > different motors. But there are other considerations where they are
> > "totally not interchangeable." Velocity control is one additional
> > difference. For this issue I'd include the step and direction servos
with
> > the steppers.
> >
> > Velocity control says, go to this position at this rate. Steppers and
> > step and direction servos, have no equivalent command. The difference
might
> > not be important for hobby uses, but I've seen operators in the shop
> > need to put a 0.0015 taper on a 10" shaft. Using velocity commands, the
> > result is a nice smooth cone. Using step and direction, the result is a
> > set of steps with cylinders between. You might not think that you can
see a
> > difference of 0.0015 but you could see it's reflection by rocking the
parts
> > under a good lamp. You will also see the diference near the quadrants
> > when milling large circles.
> >
> > Hope this muddies the waters, but not to much.
>
> Yes, this is a good part of the reason why I'm a (real, velocity) servo
bigot.
>
> Jon
>
>
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