NavList:

I have done a little checking of the available commercial MEMS products that might be used for such a device. A good candidate is the Analog Devices ADXL203 dual axis accelerometer, which costs less than $10. Temperature sensitivity is an order of magnitude better than I had remembered for similar products, only .1 mg per deg Centigrade.

See
http://www.analog.com/en/mems-sensors/mems-accelerometers/adxl203/products/product.html

Also take a look at the application note for using the ADXL203 as a tilt sensor:
http://www.analog.com/static/imported-files/circuit_notes/CN0189.pdf

Temperature sensitivity remains a major concern, but I think that the technology has reached a point where compensation is feasible, either by individually calibrating each device (expensive for a low cost product) or by adding on a constant temperature box to hold the circuitry. But for not much more than $100, a graduate student could experiment with attaching the ADXL203 to a small telescope and measuring altitudes.

One other aspect concerns me. For purposes of celestial navigation, the sensors must resolve the gravitational field to less than a milli g. I wonder if this would ever be practical for a hand held device, even with lots of low pass filtering of the signal. It might be necessary to use a very stable, vibration damped tripod to aim the telescope. And that then leads to the question of the motions of the ship, the pitch, yaw, roll and the mechanical vibrations of the engines.

But go ahead and assign this as a term project or even thesis to an engineering student. It would be interesting to see the results.

Don Seltzer
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