Thread: Basic questions about the GYRO ADXRS300
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Unread 03-09-2009, 09:04
Russ Beavis Russ Beavis is offline
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Re: Basic questions about the GYRO ADXRS300
If your oscilloscope probe is DC-coupled and the gyro isn't spinning, you should read an output that is about 1/2 of the power supply voltage. That's the "zero rate offset" for the gyro and it will be somewhat dependent on time and temperature.

After you subtract off the above offset, the observed output will be proportional to the rotation rate of the gyro about its sensitive axis and is a real-time measure of the rotation rate. For example, if the reading is 500mV above the offset and the gyro's sensitivity is 5mV per arc deg/sec, then the gyro is indeed spinning at 100 arc deg/sec at that specific time about its sensitive axis (it could also be spinning about a perpendicular axis and you wouldn't be able to tell). If that 100 arc deg/sec rate is maintained consistently for 1 second, then the gyro will have rotated by 100 arc degs.

You just need to apply an integrator to (reading - offset) to determine the position of the gyro in degrees. BE CAREFUL WITH THE INTEGRATOR - a small amount of error in your estimate of "offset" will result in an integrator output that grows over time. There are ways to minimize that error but that's worthy of a separate chapter.

Russ