I have a F450 quad with APM 2.6 AC3.2. Recently I'm getting BAD DCM Heading error and the copter goes into LAND mode. This is happening very frequently. I have mounted my GPS Compass on a mast. I didn't face this problem earlier. Compassmot showed mag interference of 3%. So what is causing this? Pls help me in identifying problem.
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Those links all point to bad compasses or interference. You should at least try doing a compassmot.
You won't believe this but due to this we are very scared of quad flying off and hurting someone. So all our tests have a long but loose tethered harness. In case the beast flies off, we can pull it back :-)
It's looks more a GPS problem than compass, check it please, You activate land or the APM do it?
Can you show us your cuad photo?, You where flying near trees, buildings?
+Cala
GPS seemed to be fine. I had between 8-9 sats in view and HDOP was fluctuating between ~2.15 and ~1.7. Had clear view of the sky. The HDOP gets better during evenings!
Photo attached. 3D printed frame. Ignore the protective ring. It was taken off before the flight.
Land was activated by me.
IMG_20150419_114350.jpg
Which way is front? Compass doesn't seem to be centred and doesn't even look like it's facing right direction unless you are using '+' config.
Red is front - X config.
Good catch on compass. I had turn the caddy slightly to calibrate the North of DCM to North of my phone shown by Compass 360 app. You will see an abandoned screw hole. Ideally I should have turned the whole unit but the zip ties was tight and I ran out of ties so did not want to cut it. The unit is facing forward in same direction as APM.
Does it have to be centered? I have seen frames with GPS caddy in tail or nose ( Alien 560 for instance).
Centreline is ok. I really don't know if it makes much difference, but certainly pointing in the right direction is important! I had thought the wire was south on those units, but if you are sure it's fine. Log shows ErrYaw going to 1 again - many times. Need to see compass log :) Do you get pauses during compass calibration? I do and turns out that's when MP was receiving no data.
Mode is AltHold, no GPS involved I think?
That true, but I don't shure if always check for err, he have the err check but not failsafe err, perhaps a mechanical failure can be too because pitch can't follow the desired values and baro is strange too because it goes under 0. As you recommend it's better enabling all log and test again.
How do you switch on compass logging in data flash?
I have also moved the GPS+Mag up by another 3 cm. Will do another flight and check if it will make a difference. Will also run another compassmot before since the GPS+Mag unit is moved up and offsets need to be re-calibrated.
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