Re: [CAD_CAM_EDM_DRO] sine wave encoder outputs

dave engvall wrote:

> Elliot Burke wrote:
>
> > Does anyone know a way to convert (4 phase)sine wave encoder output
> to allow
> > interpolation of the phases?
>
> I think the usual approach is to count zero crossings and a/d the sine
> wave , scale it and add to the counts.
>
> This is what Heidenhain (sp). does with some of their encoders.
> A post some time ago talked about doing the same thing with optical
> encoders.

There are a number of commercial units on the market for doing this. It
has been
done since the mid 70s, at least. There must be hundreds of journal
articles on
this. For CNC, rather than DRO, however, you need TIME interpolation as
well
as just distance interpolation, so the interpolated encoder pulses are
output so they
look just like a real encoder of higher resolution would produce. Also,
if the CNC
servo update rate is 1 KHz, then the interpolator must be able to update
its output
at at least that rate.

Jon