Arducopter problems in flight modes using GPS


I'm having some strange problems with my hexacopter. The aircraft flies well in stabilise and alt hold but as soon as I switch to loiter or auto it flies off in a random direction whilst increasing pitch. It will eventually be almost vertical before I recover in stabilise mode.

Everything is well padded with foam and I have good GPS lock according to the logs. Does anyone have any ideas as to what could be happening here? Any help is much appreciated.

 I've uploaded logs here

And a couple of videos here

I ran compassmot getting a value of 62% and tried the flight again. Still having issues. The APM seems to be ignoring the external magnetometer and is using it's own instead despite changing the setting in mission planner.

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  • This is an update for anyone still following this post.

    The new GPS receiver and external compass solved my problems. Compassmot give me an interference figure of 0%.

    I had a number of test flights yesterday and all GPS modes are working well. I'm actually blown away by how differently the aircraft behaves.

    Thanks for all the help.

  • It was packaged with an RCTimer APM 2.5. I've had a few problems with this APM. Next time I'll be buying a 3DR set. I was cash strapped at the time but I wish I'd spent the extra £50 and gone with 3DR from the start. 

  • 3DR was selling them (3DR GPS uBlox LEA-6),

    I have one with my VR Brain 4.5, no problem with it.


  • 3D Robotics

    Where did you find a GPS module without a compass??

  • I made another test flight today after calibrating with compassmot. I have just noticed that my GPS receiver does not have a magnetometer! So I've ordered a replacement with this onboard and have cut the jumper on the APM board.

    Watch this space.
  • Hi,

    I had similar problem.

    I have done a nice calibration and ran compassmot but there was no compass interference.

    So i have put compass in learn mode and it has solved my problem.

    If you put the compass declination manually, you will have better loiter result.

    Hope this can help you.

    everything here:

  • Looking at the first log, two issues:

    - you seem to be toilet bowling on the approach to waypoint 2 so I would also recommend a compassmot calibration.

    - there is some corruption in the log entries - you may be overtaxing the APM and I would recommend disabling the IMU log as it provides minimal functionality in most circumstances.

  • Have you tried a "compassmot" calibration?

  • I thought the same with the compass issue. I have tried with the GPS receiver in both directions and am still seeing the same problem. When I view the telemetry data in mission planner the compass in the live view is showing the correct orientation of the copter too.
  • +1 on compass issue. Double-check compass orientation and settings.

This reply was deleted.