Hi guys,

(Posted this as a reply in another thread but I wanted to ask specifically about the compass)

Last week I had a really scary crash, my quad was running in autopilot and suddenly decided to take it's own route. Within seconds and before I could react, it was completely off course and out of line of site.

As a last resort I activated the RTL failsafe and surprisingly the quad made it back but it was flying backwards, unfortunately it fell out of the sky before I could land it safely.

Analysis of the logs and on board video seem to indicate that there was a compass/heading error which slowly magnified as the mission progressed. While the logs and the telemetry data shown on the laptop indicated the heading was correct, the actual heading was slowly creeping away.

As such, while it flew perfectly fine on the first 3-4 waypoints it started to get it's bearings wrong soon after and this error snowballed into a crazy race across the sky ending in a crash.

I suspect there was something wrong with the compass, but after retrieving and repairing the quad, all bench tests seem to prove otherwise. This leads me to wonder if the compass can be compromised by external factors such as interference or magnetic fields around power lines etc.

Also, how essential is the compass for navigation? Somehow my quad made it back to launch even though it was pointing in the complete opposite direction, yet it still went off course halfway through the mission.


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  • Developer

    It is possible to have external forces that will affect your compass. This can happen especially close to mountain areas and other massive Iron rich areas. There are several areas in world that you can have sudden 90 degree error on your compass readings. These sites are really rare but it is possible. 

    In your case it's really difficult to say. Have you ever flown on this same location earlier? Have you been having to have similar problems earlier?

    Which flight electronic you were using? Do you have external compass and so on. On this case it can be hardware failure or maybe software. If you give more details we might be able to help you better.

    Jani / jDrones

    jDrones, R/C UAVs and More....
    Manufacturer of ArduCopter frames and parts. Custom airframe manufacturing, Custom design services for all your R/C UAV needs
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Shivchand Jaysaval liked Shivchand Jaysaval's profile
Aug 25