retrolefty:
Interesting about the stepper encoders not being absolute. Kind of a bummer actually... Does make a simple initialize function seem like the better way to go then.
Well there are industrial absolute encoders available and many would be no problem to wire up to an arduino, but their price can be pretty much a sticker shock. The fact that with one external sensor and one quadrature encoder, you can emulate a absolute encoder function in software, pretty much tells you which way you should proceed. As far as optical Vs magnetic encoders that is pretty much internal details of the encoder that doesn't much concern one, it's just a matter of the electrical interface method and getting the steps per revolution resolutions you require for your application. You might note that most encoders are specified as having X number of 'steps' per shaft rotation, but with standard software encoder decoding methods you can turn that into detection of X or 2X or 4X steps per shaft rotation. So a 100 SPR rated encoder you can resolve 100 or 200 or 400 counts per revolution just by the software decoding method used to decode the A and B encoder signals.
Lefty
Funny you should mention sticker shock. What got me started down this road was just that, sticker shock when I looked at purchasing a prefabricated simulated aircraft compass and found they cost between $500 and $700 US. That said, the lower the cost the better, but I suspect there are many options that would put me well below that mark.
I wonder if you might know of any such steppers absolute encoders that you could point me to as an example? That would allow me to access the cost/benefit as compared to likely less costly options.
Thanks!