Re: [CAD_CAM_EDM_DRO] Quadrature?

In a message dated 23-Mar-02 03:24:17 Central Standard Time,
scotr@... writes:

> Now, more questions. If an encoder, say a rotary encoder, has a count per
> revolution of 2500, and I have a pitch on a screw that is say 10 tpi. Then
> its possible to have a dro with .00001"? (one hundred thousanth of an
> inch)
> Or does the initial count of the encoder mixed with th pitch of the screw
> make the difference? Or does the screw have anything to do with it at all.

Scott! You flatter me! So I will try: I have actually done very, very
little breadboarding with "quadrature" stuff. I read a buncha "short
articles" twenty-five years back, but I don't now even recall which
file-drawer all that is now in! Let's see if I can make enough sense of this
to answer: First, I am very flattered that my simple-minded response was
useful to you. Best I could do, anyway! If your screw moves 0.1" linearly
with one turn, and your encoder has 2500 "counts" per revolution, do you mean
2500 "HI-LO" transitions in "A" and 2500 [same] in "B"? Then, each
"full-wave count" would be 0.1"/2500, or 40 millionths per count. WOW! With
proper "edge-detection techniques", you could count each "LO-HI", and "HI-LO"
transition PER channel, for 4 TIMES 2500, or 10,000 "edges" per tenth-inch
linear move, but I suspect you have the number-definition confused. Too,
this is about the extent of MY wisdom, so I best stop and let one of our
sages in this group respond! Jan Rowland


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