Gyroscope drift on mobile phones

Question

Lots of posts talk about the gyro drift problem. Some guys say that the gyro reading has drift, however others say the integration has drift.

1. The raw gyro reading

Answer 1

The dear Ali wrote something that is really questionable and imprecise (wrong).

The drift is the integration of the bias. It is the visible "effect" of bias when you integrate. The noise - any kind of stationary noise - that has mean zero, consequently has integral zero (I am not talking of the integral of PSD, but of the additive noise of the signal integrated in time).

The bias changes in time, as a function of voltage and exercise temperature. E.g. if voltage changes (and it changes), bias changes. The bias it is not fixed nor "predictable". That is why you can not eliminate bias using the proposed subtraction of the estimated bias by the signal. Also any estimate has an error. This error cumulates in time. If the error is lower, the effects of cumulation (the drifting) become visible in a longer interval, but it still exists.

Theory says that a total elimination of bias it is not possible, at the present days. At the state of the art, no one has still found a way to eliminate the bias - based only gyroscopes and accelerometers magnetometers - that could filter all the bias out.

Android and iPhone have limited implementations of bias elimination algorithms. They are not totally free by bias effects (e.g. in small intervals). For some applications this can cause severe problems and unpredictable results.