Gyro question

Hello,
I'm working on a small mobile robot and I wanted to add a gyro for rotation sensing. Has anyone used one of those commercial gyros (the ones
used in RC helicopters and planes) for sensing angular velocities?
Thanks for your help.
RaX
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RaX,
I saw a demo of the Analog Devices rate gyro at a show. They had a 3-D gyro in a box attached to a PC which would display a graphic representation of the box on the screen in the same orientation. It was a cool demo, and I didn't see much drift. These sensors designed for cars to sense rollover for correct airbag deployment based on car attitude. I think a single axis sensor from analog.com is about $36/unit; but you'll have to interface it to your controller.
The rate gyros for helicopters drift a bit (check the manufacturer for drift rate spec); however, they usually have a seperated sensity input to adjust how much to effect the servo output. They cost more, but are complete units.
For absolute rotation sensor on robots, you can use an electronic compass. Precision Navigation has some small 2D compass modules for $50 that interfaces via SPI bus. I think they have a readout accuracy of +-1deg. They have raw (uncalibrated) mode and a calibrated mode, where you can map out soft iron declination. I have used them and they work pretty well.
I don't know what the availability of any of these are in your country.
See ya, -ingo

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/* Ingo Cyliax, snipped-for-privacy@ezcomm.com, Tel: 812-391-0895 */


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What are you trying to sense? Low-end rate gyros are not very accurate. Do you want to know which way is down, or which way is north?
Rate gyro plus magnetic compass can produce a reasonably good heading outdoors.
                John Nagle
RaX wrote:

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