IMU calibration method only calibrates offset bias, there seems no scale bias estimation in calibration

[mgrouch]

Calibration method only calibrates offset bias, there seems no scale bias estimation in calibration.

Calculation of scale bias is missing from calibration. As taking it into account on update.

There is no sphere fit calibration. It's very primitive and insufficient in current implementation.

Here is one project from which code can be re-used:

https://github.com/alinja/magnetometer_calib/

Thanks,