Low-Cost MEMs-Based Gyroscopes

Chris writes "Recently, Analog Device released their new line of MEMS based gyroscopes. The release was announced in this article on Small Times about a week ago. The gyroscope is roughly 7mm. x 7mm. x 3 mm. While MEMS gyroscopes have been commercially available from other companies for a while (e.g. Silicon Sensing), these are fairly expensive ($100+ per gyroscope). The Analog Device's gyroscopes cost $10! In fact, you can request free samples from the Analog web site! Mmmm, new low cost Lego Mindstorm sensors."

Comments

It's a gyrometer ...

[fini]

... not really a gyroscope. You must integrate to get an absolute indication. Also, at 0.05 /s/Hz^1/2, don't count on it for your next homemade ICBM. Still, it's really tiny cute cheap and all that. I guess the main applications will be in cars (or Segways ...)

Re:It's a gyrometer ...

[Anonymous Coward]

You are right that it isn't going into any ICBM's because it has too much noise and drift, and it is an angular rate sensor, not an angle sensor.

Still, it could be useful in conjunction with a cheap GPS in some kind of unmanned vehicle to keep track of sudden yaw events. You could build a relatively low-cost IMU from three angular rate sensors and three accelerometers, and you would use the gps position and heading data to eliminate long timescale errors.

Actually, it's kind of exciting.

Re:Pardon my ignorane

[Merlin42]

Actually it measures angular rates ... you can integrate to get angles. It has a range of either +- 150 deg/sec or +- 300deg/sec depending on model. the 'noise density' is .05deg/sec/sqrt(Hz) meaning (if i am reading this correctly) that the faster you measure the more accurate each measurement is, but you have to integrate more ... btw i dont usually work w/ hardware so I might be misreading the specs a little. So with it saturating(or going nuts) beyond 25rpm or 50rpm this will be just fine to measure the orientation of a robotic arm but will not keep track of how fast your spinbot is spinning.
Also remember that this is a single axis gyro so that you need at least 3(4 if you want to avoid the dreaded gimbal lock) if you are interested in a complete orienation.

What gimbals?

[Spamalamadingdong]

Also remember that this is a single axis gyro so that you need at least 3(4 if you want to avoid the dreaded gimbal lock) if you are interested in a complete orienation.

No, just three. Gimbal tables are used on rotating gyros so that you can't get two of the axes into the same plane (the "lock" condition) and then twist along the perpendicular axis. Using rate gyros like the AMD units, you are just sensing rotation rate around 3 axes referenced to your sensor array; there are no gimbals to lock and if your sensors are on 3 perpendicular axes (and why wouldn't they be?) you will always be getting data from 3 mutually perpendicular axes. The orientation of these axes will vary in space (unlike a gimballed table carrying rotating gyros), but you really don't care; you're unwinding your gyrations with arithmetic instead of wheels and bearings.

Me, I'm waiting for the cheap unit that's sensitive enough to measure the 24 hour rotation of the Earth. Not because I have any wonderful use for it, but just because I think it would be cool to have something that sensitive which I could buy for ten bucks.