is a piezo gyro made with accelerometers or is it somehow different?accelerometers measure translation and not rotation, correct?which is more commonly used, a two-axis or three-axis accelerometer?also, which is a good one to use (for testing / learning)?how do you account for the drift due to error in finding down (gravity vector) other than the co-pilot method?i'm goin with the propeller chip so i'll prolly just use the two axis one that parallax offers. turns out they sell them at radioshack so that's pretty sweet. i'm not at the point of trying to put together an IMU or anything. at the moment I'm just trying to learn how to use the processor.~ nolin
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so then does that mean gyros measure rotation? or do they also measure translation? are there cheap gyros that are usable for learning with? the cheapest one i found is $74.95
1) gyros and accelerometers are different, although they're based on releated MEMS technologies.
2) correct
3) You need a three-axis accelerometer for an IMU, because you're moving in 3D space
4) You combine accelerometer readings with gyro readings (using code called a Kalman filter). Accelerometers are wrong (noisy and thrown off by inertial forces) in the short term, but don't drift. Gyros are right in the short term but drift. You use one to correct the other.
5) The Propeller is a good choice. The two axis sensors will be fine for learning with.
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http://www.sparkfun.com/commerce/product_info.php?products_id=698
thanks.
~ nolin
2) correct
3) You need a three-axis accelerometer for an IMU, because you're moving in 3D space
4) You combine accelerometer readings with gyro readings (using code called a Kalman filter). Accelerometers are wrong (noisy and thrown off by inertial forces) in the short term, but don't drift. Gyros are right in the short term but drift. You use one to correct the other.
5) The Propeller is a good choice. The two axis sensors will be fine for learning with.