Gyros and other inertial sensors

In the late '80's I was working at Sperry on chips for Fiber Optic Gyros (FOG's) that were supposed to be so cheap that they could be used in cars. In fact, at one point in the development, we had a demo presented to us by Toyota.

I've lost touch with that end of business... do FOG's still exist? ...Jim Thompson

Yes they do, but the least expensive ones are probably $500 to $1000, with prices going up from there until they intersect with prices for ring laser gyros (out of my league -- I suspect $100000, but I could be off by almost an order of magnitude).

I suppose you could build a FOG for a few bucks in quantity, but there's a whole lot of tweaking and tuning that you wouldn't be able to do, never mind the fact that winding the fiber onto a bobbin then terminating it is going to have no end of yield issues. When you were done, you'd probably have something that cost a whole lot more than a similar performance silicon or quartz MEMS.

AFAIK, the gyro biz kind of goes like this:

order of M: | | | | | silicon MEMS: *************** quartz MEMS: *************** mechanical: **************************************** FOG: ********************************* Ring laser: ******************

You pays your money and you gets what you pays for.

Actually ring laser ones are not that expensive. I think this one at 1 degree/s is only around $15K :

That's an entire 6 DOF IMU- 3 accelerometers and 3 gyros.

"Export licensing restricts operation to a maximum of 18,288 meters and 514 meters per second"

Best regards, Spehro Pefhany

I _did_ say I could be off by a factor of 10!

I.e. don't buy it to put into your best cousin Ahmed's SCUD missile.

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The Inertial Reference device that we buy from GE runs about $50k each. It is about an 8 inch cube and the hi-res GPS antenna gets remotely mounted from it. Works great for keeping a dish pointed at its bird in a mobile setting.