Crazy Magnetic Interference

I am having huge problems with magnetic interference when I fly my quad.  I had recalibrated the compass dozens of times, replaced the gps/compass, raised the gps as high as the wire will allow (10cm).  I even moved the battery and power wires under the frame.  But you can see in the logs where the magnetic field spikes which causes significant yaw drift and then soon violent toilet bowling.  

System

DJI Flame Wheel 550

Pixhawk 

External GPS on mast

Ardcopter V3.1.5 ( i even tried the latest beta release of 3.2)

8 45 blades

30C 2800 LiPos

You can see the toilet bowl effect and the magnetic field levels in the logs (attached).  Please, any help would be appreciated

2014-08-25 16-59-47.log.zip

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Replies

  • I believe I have found the problem.  Poor wiring to the magnetometer.  I replaced the wiring and now the interference is down to about 7% and I haven't seen TBE in 2 flights.  Thanks for everyone's advice, it helped me take everything apart and figure this out.  

  • Is it possible to check in the logs which magnetometer the pixhawk is using during the flight?  I set it to use the external one but my understanding is that the pixhawk decides on its own which one to use.  

  • Try twisting all your wires to help eliminate spurious EMF.Bend away sideways the cloverleaf,it dose not matter about its orientation.Check BEC,add a capacitor for eliminating voltage spikes.Tin foil is quick shielding to test,be weary of shorting something.Go back to later stable versions of arducopter.

    Hope this helps

  • compassmot doesn't work with pixhawk yet as far as I have learned.  Yes, I actually attached the battery underneath the whole rig several times and tested with same result

    • T3

      Are you sure it doesn't work? I ran it just fine on my TBS Disco using a 3DR Pixhawk and GPS/Compass combo.

      • I read some posts from the developers saying that compassmot produced flawed readings with the pixhawk and was slated to be fixed in 3.2.  

    • Moderator
      Hi Ted,
      It might be worth trying some shielding to see how it works, I have had very good results with it. Best to use printing plate if you have access to it as it's very light, if not then copper clad circuit board. Get a piece a few cms bigger in diameter underneath the GPS unit. The 5.8ghz antenna is still way too close, best to orientate downwards to avoid interference (I know you have been disabling the tx). This fixed my gps issues, best of luck.
  • Thanks.  It is setup as an X with the GPS and pixhawk pointing forward.  

    All the pixhawk setups I have seen online have the Pixhawk on the power distribution board and the battery on the top platform.  Is that incorrect?

    • Have you done the compassmot test ?

      Imo the battery might be too  much close to the compass, try to put the battery under the frame,

       

      • The battery on top doesn´t cause this behavior. I am flying/flew several PX @ F450 (lately 3.2 rc5) this way w/o any TBE issues with an external MAG / 3DR V1.2/CSG NEO 8 . Even CompassMot isn´t really required, at least I didn´t even bother.

        Just check that the internal MAG is not used, or use a sep. MAG BOB (e.g. cheap GY-281) just to verify that your MAG @ the V1.2 doesn´t cause this ..as well as bad SDA/SCL connections could cause trouble too.

        Some examples of my working setups :

        a7037921-170-3xGPS%20cutoff.jpg

        ysennuii.jpg

        rbwf2iiu.jpg3702664804?profile=original

This reply was deleted.

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