Police radio causes fly away?

My quad was flying an autonomous mission flawlessly. I had it doing a set of radius loiters and when complete it was supposed to return to launch. All of the sudden it flies off and ends up 70ft up in a tree. Within a few seconds a police car that was about 200ft away speeds off with blue lights flashing. I ran an analysis on the log and it said that there was a compass failure. The log said there was a sudden change in the magnetic field of 38%. I should have landed the quad before it hit the tree, but I kept thinking that it was going to turn back. Had to call a tree service to get it down. Broke an arm and my camera gimbal, but have repaired everything. Could the police radio have caused the flyaway?

Test: Compass = FAIL - Large change in mag_field (37.84%)

I’m doubting the police radio did this.

None of this is probably very helpful but - its more of a chunk of thought out of my head. I’ve helped my brother troubleshoot some compass issues like this…flying in a location that is similar to this.

Compass readings are hardly a static thing and based on my personal observations (meaning I’m no authority on the subject by any means), are worse when yaw-ing, or moving laterally which kind of makes sense to me.

I’ve seen the readings go straight into the red, I believe even higher than this (like 40% or more) with no fly away or anything near what’s happening with you in this instance. And it seemed to be a fairly quick anomaly in just about every case.

This happen to us when he had a Gopro 3 wifi turned on, which interfered with the RC. But I attributed that to the radio, which was constantly giving us RSSI low warnings - and turned out to have a problem. A new radio solved that one. I’ve had no issues running 2.4ghz right next to my transmitter, in flight (using a pi companion - even though people say it’s a bad idea). I’ve had my pi setup with 2 wifi dongles - one which connected to the gopro wireless on startup, and sent wget control through the pi for camera control. I didn’t have any specific interference or noticeable loss in signal from it.

I had an issue like this on mine, when one time my gps mount came loose…the gps fell and was hanging upside down by the cable. We somehow managed to land it but what a journey lol.

I don’t see the police vehicle anywhere in the video prior to this happening.

I also don’t know of any system or equipment that police use that would interfere with our drones.

I wonder if that building across the street might have some type of microwave emissions for radio or even a long range style directional wifi or something that you just happened to cross into the direct path of. It looks like it could be some type of public works facility and that wouldn’t be uncommon in a place like that - the wireless and radio stuff that is.

2.4g devices are friggin everywhere and some of them can quickly overwhelm others.

You had just finished a waypoint - it appeared - when this occurred. I’ve been a dodo head before and set my waypoints wrong and had some weirdness like this.

Just some thoughts - that sucks when it’s questionable why something like this happens.

There is a police car there. It’s behind the trailer with logs on it that is behind me. I’m about 100% sure that he made a call right about the time the quad flew off. I spoke with him later that evening. I’m standing near the intersection.

I was running a mobius, but the GPS/Compass are on a mast and the camera is on a gimbal hanging below the frame. As far as the waypoints, I checked that by downloading them after I got the thing out of the tree.

I’m going to do a compass/motor calibration once I get up the courage. Anything is possible.

CompassMot is really easy. Move the props one position over, connect to mavlink, then go to Advanced Compass Calibration in MP. It will even arm it for you when you click on Start if memory serves. Once it starts, move the throttle up to at least 75 percent for about 5 seconds and cut throttle quickly. As long as you’ve done the props right, they’ll be inverted and full throttle will just mash you into the ground.

Oh, I’m the brother Lance_B refers to here. :slight_smile: We’ve been working on building these things now since October of 2014. Have learned quite a bit along the way.