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
Replies
In the past I have made some measurements with a specific instrument to check if something could interfere with the mag and I have learn several things.
Batteries cables path is crucial, especially if you use more than a single battery as I do.
Non piezo buzzers interferes a lot and also iron bolts that might have become magnetic can play a role.
Most important aspect is the distance of mag from interferences, if I remember well interference decrease with the cube of distance.
Ted, I would suggest you to try to increase the distance of the mag from the frame.
Even 5 centimeters, 2 inches , will make a huge difference, the more the better and you should see a big improvement , if nothing changes, the problem is elsewhere .
How much efficient is your copter ?
I mean with how many grams / watts do you usually fly ?
If your copter need a lot of Amperes the magnetic interference will be higher.
The toilet bowling effect happens only when you are il Loiter mode , do you confirm ?
Make this test I used to do with 3.0.1 version: hover in Altitude Hold mode, with no wind and look at the heading of the copter.
If you'll see that the copter slowly start to rotate and finally , after 30 seconds and around 180 ° , become stable , then the problem is really of the magnetic interferences of the compass.
Hi,
Could you add a picture of your quad with all equipment etc installed ready to fly?
I had issues with mine which was due to the telemtry aerial I was using, which would flex slightly in flight and get too close to the the compass in the process, changing the magnetic field almost randomly ... could be whats happening to yours.
Also whats GPS/compass aer you using? I also had an issue with the metal screws of the 3DR GPS/compass combo case becoming magentised, however this was very evident when calibrating the compass (you would get very large offsets).
Regards,
S.
Sorry just realized my typo above. it is a 450 not a 550
Hi Ted,
How is it going now? I am not expert at all at this hobby, but I saw that the Vx is pretty close to the GPS (also at the same height), it might be the case? Hopefully it helps.
Do you mean the video transmitter? Maybe, but I have tested with the video system disconnected and still had the compass problem. It is still over 10cm away.
In Photo 2-4 you can just see the Pixhawk and its directly on top of the power distribution board. That can cause magnetic interference.
Also a quick question... is this craft set up as an + or an X? If I look at the arrow on the GPS it looks like its a + but the arrow still does not seem to line up straight with the arm.
Here are some pics. I have tried re-routing the power wires several times but all with the same problem.
photo 2-4.JPG
photo 1-4.JPG
Will get a picture up when I get home. But I have tested with all other radios disabled, no video, no telemetry, even had the battery hang down over a foot below the quad. Same issues. Flies well, then starts to yaw drift, then goes into extreme toilet bowl. Log data shows huge jumps in magnetic interference but I can't figure out what causes it and what condition initiates the problem. I keep all the other radios at least 10cm away from the GPS
My GPS is a 3DR, but I have tried 2 different units.
Hi,
do you use a battery alarm connected to the balancer connector of battery ?
No.
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