DRO:Inductosyn
Posted by
Arne Chr. Jorgensen
on 2000-03-16 16:09:35 UTC
Hi all,
Just a few word. ( have some problems with my ISP - just hope I will be able
to get this across )
Ian wrote:
cuts across it" )
I have waited for someone to say something about this. The reason is that I
have suspected that this is one of the commonly used systems.
1. It should be easy to make as a home-brew system ( easier than making optical
strips )
2. It can get very high resolutions
3. It is not affected much by contamination
4. Easy make it into any length
5. No critical alignments, close fits, etc.
6. Can be made cheap
It is called an indoctsyn. ( could have other names too ) It looks much like
a resolver, and the principal is much the same. You have one etched track that
runs all the way like if you would draw a square wave. Then you have to
similar tracks as "pick-up" sensors. The long "square wave shaped" ribbon
that runs all it's length will act as a winding in a transformer, and the other
two "windings" will "pick-up" the induced voltage. These "pick-up sensors"
is placed like you would place "photo sensors" for linear optical strip, -
i.e. 90 degrees out of "phase" . The main "square wave shaped" ribbon is feed
with an AC voltage.
This may be feed to a "Scott-T" transformer, parts of it's output may be feed
to a sin/cos multiplicator, part to a demodulator and VCO.
This can be feed to a up/down counter for position. And you also have the
velocity from the demodulator, - so it could be a very nice unit for a servo
system.
I am not going to say much more about it, - but I would just say that on some
"old and big" printers from IBM, - they used this. ( take a look in your
dumpster - wish I had one, - then I would do a little testing on these :)
Another thing I believe have been used, is "magnetostrictive" systems. I have
seen something that I just can't think could be anything else.
Well, this is all I am going to say about this. I don't have any info on how
high resolution you can get in a cheap "home-brew" system, nor do I have any
schematics. But I have wondered many times why nobody have mentioned this
system.
//ARNE
( let see if I am able to send this .. )
Just a few word. ( have some problems with my ISP - just hope I will be able
to get this across )
Ian wrote:
>( I could be wrong here, as I am not sure about his description -" diagonal
>At a slight tangent to these discussions, does anyone know how the Mitutoyo
>digital vernier works? Mine has a bit of the scale torn off at the very end
>and under it appears to be a length of something like printed circuit board
>with diagonal cuts across it. I assume they must use some form of quadrature
>sensing on these copper parallelograms but I can't think of either how they
>would sense the presence or absence of copper without touching it (it's
>under the thin plastic adhesive scale) or how they would get the required
>resolution of better than .0001" with something which seems so crudely made.
cuts across it" )
I have waited for someone to say something about this. The reason is that I
have suspected that this is one of the commonly used systems.
1. It should be easy to make as a home-brew system ( easier than making optical
strips )
2. It can get very high resolutions
3. It is not affected much by contamination
4. Easy make it into any length
5. No critical alignments, close fits, etc.
6. Can be made cheap
It is called an indoctsyn. ( could have other names too ) It looks much like
a resolver, and the principal is much the same. You have one etched track that
runs all the way like if you would draw a square wave. Then you have to
similar tracks as "pick-up" sensors. The long "square wave shaped" ribbon
that runs all it's length will act as a winding in a transformer, and the other
two "windings" will "pick-up" the induced voltage. These "pick-up sensors"
is placed like you would place "photo sensors" for linear optical strip, -
i.e. 90 degrees out of "phase" . The main "square wave shaped" ribbon is feed
with an AC voltage.
This may be feed to a "Scott-T" transformer, parts of it's output may be feed
to a sin/cos multiplicator, part to a demodulator and VCO.
This can be feed to a up/down counter for position. And you also have the
velocity from the demodulator, - so it could be a very nice unit for a servo
system.
I am not going to say much more about it, - but I would just say that on some
"old and big" printers from IBM, - they used this. ( take a look in your
dumpster - wish I had one, - then I would do a little testing on these :)
Another thing I believe have been used, is "magnetostrictive" systems. I have
seen something that I just can't think could be anything else.
Well, this is all I am going to say about this. I don't have any info on how
high resolution you can get in a cheap "home-brew" system, nor do I have any
schematics. But I have wondered many times why nobody have mentioned this
system.
//ARNE
( let see if I am able to send this .. )