Doubts about Compass Calibration and Magnetic Declination

Hello guys,

I’ve been buiding multirotors from various sizes since 2019. I noticed that, independent of ArduCopter version, from times to times my drones starts randomly to present pre-arm checks regarding the magnetic field and inconsistent compasses (despite adopting compass mounting good practices). I have always performed my compasses calibrations in Mission Planner, but I would like to know if someone reccomends other GCS to perform it. Additionaly, I would like to understand better how the magnetic declination is considered regarding compass calibration.

PS: I am from Brazil and here we have one of the weakest magnetic fields on Earth, so could this explain the need for constant compass recalibrations?

Best Regards

For an initial calibration that’s fine. I would then use Magfit for final calibration of offsets and compass motor interference coefficients.

Declination is really just a static value based on geo location as the difference between magnetic and true north. It’s not really a consideration for the offsets generated during calibration.

So it is a kind of data that comes with GPS information and is took in account in realtime execution of ArduCopter Software?

Nice. Thanks for the tip. For some larger drones I used sometimes the compass-motors calibration via Mission Planner, it is worse than using this Magfit application?

Yes, exactly. There is a world model database of declination stored.

I can’t say for sure which is better as I never used the MP method so I can’t compare. But the Magfit method sure is a lot easier to implement and no issues so far.

Nice! Thanks for the information @dkemxr!