Time to have a look from 02:10 minutes. What is this calibration method?
[
Thanks for hint !
](Carplounge Autopilot Manual 2: calibrate Compass and trimm Motors - YouTube)
Its comparing the GPS heading info with the compass I think. You see a GPS map in the vid.
The first crude setting is probably to figure out how the compass relates to the craft.
I would have thought the way to refine the headings is to go round an octagon path or similar to get
measurements for several points of the compass. It's not clear why the trimming process needs
human intervention to me, or even the initial configuration, it could simply tool around figuring it
all out by itself, human just there for avoiding obstacles...
Boats have the advantage of no nearby metal work to confuse the compass, being in a magnetically clean
environment (assuming no nearby iron-ore formations!).
However a good calibration often needs full 3D movement since the magnetic field isn't very horizontal in many
parts of the world.