Help to analize Mag Compass

Cube Autopilot
1

Hi every one.

Im having problem trying to understand how to read the mags from the compass, if they are ok or not. I found this Diagnosing problems using Logs — Copter documentation , but is not very extensive or detailed.

I have posted some time ago about a problem I had landing a drone over a giant mining truck cargo bay, when as soon I was over the truck, errors about the compass show in the screen. After landing the drone over the cargo bay, was impossible to take off again because the compass problem.

Several people have told me I need a GPS Yaw, and Im ok with that, but I would like to understand what happened looking the mag log and understand the problem.

To have a better understanding of what its happening, I have asked to my customer to go with the drone by hand (not flying, motors off) over the cargo bay and move it around to get new measures with the compass and compare with the flying log.

Here is the log of the non flight test, moving the drone around by hand over the cargo bay.

By the way, im just using the GPS Compass, not the internall

compassProblem.zip (1.8 MB)

I hope some one can help me to understand.

thanks!

2

yes there are mag issues in that log

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this is the EKF mag status, it should be bellow 0.8

you might need to check your orientation of your mags, and confirm they are correct

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3

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in general terms all these lines should trend the same. as you can see they don’t, some go opposite to the direction they are meant too. again i would look at your rotation settings on each mag.

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4

this one should be showing a somewhat flat line. there is some large magnetic interference going in here. since neither are flat, my guess is something external and magnetic is near both mags.

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5

thanks @Michael_Oborne , pretty clear now, thanks!

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