Re: [CAD_CAM_EDM_DRO] DRO: Inductosyn-2

"Arne Chr. Jorgensen" wrote:

> I just add a few more words:
>
> If " the square wave shaped ribbon" - that is the primary inductor,
> (pick-ups=secondary ) is driven with a voltage U, then the secondary
> windings
> would have:
>
> u1= U*sin("omega" t) *sin("theta"),
> u2= U*sin("omega" t) *cos("theta").
>
> "omega" = angular frequency
> "theta" = mechanical angle
>
> ( You would probably write this more correctly - but I don't have
> "greek"
> letters )
>
> These secondary windings is placed 90 degrees out of position to each
> other.
> (just like "optical" sensor)
>
> Often used frequency is between 400-1200Hz on the primary. Because
> the
> "pick-up" windings will cover several of the primary windings, - the
> mechanical
> layout is not critical, as you will have an average measure. It is
> not
> sensitive to voltage, but phase.

No, the amplitude varies sinusoidally with position, and the phase flips
as the signal goes
through the zero. You need the amplitude of both pickups to
interpolate, because the
winding pitch (equivalnt to the grating pitch on an optical encoder) is
fairly coarse.

> ( If any have some schematics of the electronics, I would like to
> know. Even
> close up pictures of a pcb board could in fact help. Also anyone
> having
> anything on ordinary rotary resolvers, could help here. )

Look in an Analog Devices databook Data Converter Reference Manual, Vol
II, for the
Synchro/Digital chapter. They make the 2S80 series of chips, that do it
all. There is now
a monolithic converter, (the older ones were hybrids) but it is still
about $100 each.
It can do interpolation up to 16,384 x the fundamental resolution of the
inductosyn or
resolver.

Jon