M. Adam Davis wrote:
>
> How accurate and repeatable does it need to be?
>
> For instance, if you could rely on the earth's magnetic field, you could
> use a magnetic sensor.  It would be accurate to only a couple of
> degrees, but it would be very repeatable.
>
> But I suspect any mechanical system (gyro, piezio, etc) is going to
> drift and your repeatability would suffer.
>
> You might try a combination of different methods to obtain what you need.


I would use a send/receive IR optical (reflective)
sensor, these are cheap and simple at ranges of
a few inches and will work very quick.
:o)
-Roman

--
http://www.piclist.com hint: The PICList is archived three different
ways.  See http://www.piclist.com/#archives for details.