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larus-breeze / sw_sensor

Firmware for Larus sensor MK1 and MK2
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Avoid ferromagnetic stuff around the IMU+MAG-Sensor #56

Closed realtimepeople closed 3 months ago

realtimepeople commented 1 year ago

I have observed that we still have some ferromagnetic material around the sensor. Magnetizing this material shifts the offset of the sensors by a few percent. This is an issue, example: An offset change of the sensor channel pointing east of 1% results in a heading-error of 1.4 degrees in Germany with 65 degrees of mag. inclination !

Even pure soft-magnetic stuff will create some variable parasitic induction. We shall therefore avoid to put any ferromagnetic material like screws etc. around the sensor. If possible we shall demagnetize the complete setup after assembly. The disturbance from interfering magnetic fields from the airplane is another issue.

Our automatic magnetic calibration can reduce hard-iron effects pretty well. Soft-iron effects impair the orthogonality of the magnetometer channels, are very hard to detect and can (by now) not be eliminated by the firmware.

realtimepeople commented 3 months ago

Cannot be solved here.