How accurate are accelerometers?

Trezitorul

I am wondering how accurate are accelerometers such as the one parallax sells? And would they be viable to build balancing robots?

JohnBF

The Parllax accelerometer would be accurate enough to balance a robot, except that it can't do the job by itself. The back and forth motion of the wheels to get under the center of gravity produce responses by the accelerometer that can't be distinguished from tilt, so the robot oscillates back and forth but doesn't balance. The standard solution is to use a rate gyro in combination with an accelerometer. The accelerometer can determine absolute tilt in the long run, as the horozontal motion noise averages out. The rate gyro knows tilt accurately in the short run, but does not know absolute tilt and drifts over time. If these two sets of data are fused, the robot can balance.

Fusing can be done with a Kalman filter routine, or other approaches. Complicate stuff, but there several discussions of successful efforts using the Propeller in these forums.

/John