Compass Problem with mag field

Hello,

because I don´t know for sure, if it is a settings problem or hardware problem, I will post it here.

We have a problem, that we didn´t had with any other copter ever before. Ususally the mag_field is around 4-5% when we check the Log Analyzer.

With this octocopter, we always have around 100%-170% and this results in the “Toilet bowl” problem, when we are in loiter mode. Nothing else on the drone changed. We tried also the 3.5.7 Firmware, same result. There is a gimbal, camera and videotransmission in use, same problem without them.

We use only the external compass, which we also already exchanged, with the same result. The Here GPS Module is in this spot, pls check the second picture. Usually it is closer to the main frame, first picture, without problems, but we tried to set if futher apart from the batteries. But this also did not help.

Maybe someone can have a look at the logfile and sees something, that we are missing.

Any help would bei appreciated !

Logfile

Have you checked and or adjusted for true north / magnetic north declination?

My suggestion could be completely off the mark ( am i being punny? No just offering ideas. ) Moving the Here could create a small discrepancy. An error of only a couple degrees can lead to tidybowling . Lots of vids on it.

Hello,

thank you for the feedback, the main problem is the bad mag_field, which results in the “toilett bow” problem. But we are not sure what changed, never had this problem before, the hardware and everything is the same as in other models before.

@ Christian81 Hi…
I had similar problem and in some instances crashes associated with this problem.

The position that sort of mitigate ( a little bit ) the problem is to place the GPS/Compass much higher than the structure. (Read at least 30 centimeters above everything else)

  • Never use the internal compass pixhawk or clone.
  • Always have a very clean power supply powering the GPS/Compass (no switching noisy type)
  • When doing the compass “dance” in mission planner to setup the compass, select the “strict” parameter.
    Insure that no strong magnet are around when doing the compass setup. AND that the main batteries are on the aircraft. Of course find the proper declination for the location where you are flying.
  • if you transport your aircraft more than 20 kms away from the original compass setup, redo the setup onsite.
    ditto if temperature changes by more than 20 degrees Celsius.

select a quality GPS / Compass such as: Quality GPS/Compass

Applying the above is what keep my quads and octoquads in the air without too many problems…
:slight_smile:
Henri

Hello,

thank you also for your feedback. We solved the problem, we had two faulty Here GPS modules. They were both from the same order. A third one from an older shipment worked fine like always.

Do you know if only the compass were faulty in those units? But GPS ok?

GPS worked fine, it was only the compass that were faulty in those 2 units. I have contacted the supplier, I think they can better check, what exactly the problem with those units is.