Re: DC motor controller - servo errors

--- In CAD_CAM_EDM_DRO@yahoogroups.com, Leslie Newell <lesnewell@...>
wrote:

>
> Hi John,
>
> >
> > I can follow along with that, But doesn't overshoot & undershoot
> > still equate to missed steps or even added steps? Ruined work?
> >
>
> No. Inside the drive are two counters. One is controlled by the
> step/direction inputs and one is controlled by the encoder. The drive
> does it's best to make sure the counters match. If the motor

overshoots,

> the counts don't match up so the drive turns the motor back until they
> do match.

The difference has to occur before the motor moves. if they are both
matched, there is no need for movement, but as soon as one move a
little, the other needs to follow.

In our minds, we usually think there is no difference, but in reality,
there has to be a difference. A good driver will keep that difference
very small. in fact, tuning is about keeping that difference small.

Dave