Re: [CAD_CAM_EDM_DRO] DRO ENCODER TOOL

>
> From: "jguenthe" <jguenthe@...>
>
> Ok, let me throw some of my ignorance in on this subject! When you say
> absolute encoder are do you mean a strip that really has say 1000 lines per
> inch for example?

We are comparing apples and oranges here.

What I mean when I say "Absolute Encoder" is a strip that has the
current position encoded directly on the strip.
There needs to be a bunch of sensors, rather than 2 or 4.

The Quadrature encoders we are talking about have no such info.
You must "home" to a known position, then count the pulses to
determine a location at any given point in time.

A full absolute encoder would have one bit change at each step, .001 in
your example.

Say we used 16 bits, The high order bit would change only once for
the length of the strip, the low order bit, on the other hand would
change every other step, and would have 500/inch, the second bit would
have 250....

A hybrid setup that combined an absolute position, and a higher
resolution secondary sensor may be a good option.

Maybe a system with 128 position/inch that knows where it's at to within
1/128th of an inch, until it moves slightly and can pick up the full
resolution of .001 maybe.

> If so then would that mean that a 250 line per inch strip
> with a quadrature reader would give you .001 or better resolution?

You would get 1000 signal changes/inch,
but NOT better unless you redesigned the reader.

>
> John Guenther

Marc