I have been developing mainly on companion PC, so I have been flying my octa with a one and a half year old release: APM:Copter V3.4-dev (78442b7e). I know, it’'s not even a stable, but we have flown probably 3 hundred hours without any single glitch. All of the sudden the system just committed suicide and I would like to understand why. Furthermore if this can be of any help to developers, even better.
My setup: Pixhawk 1, GPS M8M with magnetometer. Both the Compass were selected as in use.
The facts: last day I flew a total of 4 missions, both in Loiter and Auto mode. The first one went smooth. During the end of the second one I had some “high compass variance”, even though the system was flying smoothly. Before the third flight we calibrated the compass again, took off and still high compass variance, but the UAV was fine, the heading was correct no visible issues. I removed a component that I thought it might interfere and tested again.
Took off in Alt hold stabilize and the system immediately looked weird and not responsive, like the attitude was wrong. I set in AltHold to try and recover it but at that point the system started to roll and pitch and then it flipped and crashed. It was not a mechanical issue, the EKF variances were all red and the attitude completely wrong.
I checked the telemetry, I do not see any inconsistencies in accelerometers and gyros
The magnetometer is not consistent at all (still don’t know why)
Now, I understand that everything point to the compass, but the question is how the EKF can be driven so crazy by the compass, even though the sensor is tagged with an high variance, in a manual mode. And why the system did not selected the backup attitude estimation when the primary went bad.
Here is the bin: 2017-07-28 14-19-27.bin (368 KB)