Has anyone had experience with compass calibration on a very large drone? On platforms with 1600mm+ frames and close to 55lbs it is not feasible to perform calibration on all 6 axis’s while holding the drone.
I suppose one could build a rig that suspends the aircraft to help with initial calibration but would not be practical for calibrations in the field. (i.e. re-calibrating in a new region)
Does anyone know a solution to this problem?
I think in flight calibration will come in AP 4.0
Also i dont think it’s necessary to recalibrate the compass at each flying site unless you’ve actually changed electricals that might affect the compass. I know that many people don’t and I don’t.
There’s some discussion on this already, I’ll see if i can find it.
Here’s where I asked a similar question:
And some more discussion of compasses:
And of course this vey interesting blog post about flying at the North Pole, one of the places where some commercial autopilots specifically prohibit:
Thanks for the info. That seems like a viable solution but I would rather wait until it is released in a stable FW release. I would be hesitant to test any new feature in-flight on a large drone with an expensive payload.
Thanks also for the informative response. I was under the impression a compass calibration would need to be performed when moving a large distance (i.e. East coast US to west coast US).
Our missions require the best precision possible when it comes to heading. It is important for the drone to face the next waypoint directly and not deviate during a flight line.
No, not true. Compass calibration corrects for effects local to the craft from magnetic interference. This is often confused with declination which is geographical.
Unless the location of your magnetometers on your aircraft changed, or your configuration of the aircraft changes in a way that would change the magnetic field (see the Magnetic Interference page), you should only have to calibrate your compass once. As long as you have a GPS, your declination should be automatically set and you’ll be good to go.
I believe the sky viper team got around doing the compass dance by referencing a calibrated compass with their un-calibrated drones. The process went like this:
Calibrate a compass, and you end up with something that accurately reads Earth’s magnetic fields. Place it in a specific XYZ coordinate on Earth and record what the compass says.
Place an un-calibrated compass in the same exact XYZ coordinate. That compass’s readings subtracted from the true compass’s readings is your offsets. You don’t get all the diagonals but you do get a flyable calibration.
Or, as others have mentioned, in-flight calibration is on its way.