Up until yesterday, things were going well.  I could loiter, RTL, and fly auto with no issues. But there was one little annoyance-- The heading was always pointing about 15 degrees off from the actual course the hexa was flying in auto mode, with the result that the hexa was always flying kind of sideways.

I decided to try the COMPASS_MOT procedure, to see if that might help.  I did it, and got some nice low values, Unfortunately, my first flight with loiter, the hexa was now doing the toilet bowl thing. I have no idea if COMPASS_MOT fixed my yaw problem or not, because I went into the parameters and zeroed out the values to see if I could restore the prior good performance.

Next test flight, everything looked good.  It loitered and RTL'd until I was coming back to land, and suddenly the controls started getting flaky on me.  I ended up crashing hard from about 3 meters  and breaking an arm off on my hexa.

I replaced the arm and sent it up again.  This time, when I put it in loiter it didn't take long for the hexa to apeshit and start veering all over the place.  Controls had barely any effect.  I switched modes rapidly trying to save it and managed to barely avoid a bad crash.

So, Log Gods, WTF?  At this point I'm afraid to fly it.  I have no idea when is going on all of a sudden with what was a nice flying machine one day ago,

Attached are tlogs from crashes 1 and 2, plus the parameters saved from when I had COMPASS_MOT.

Thanks in advance


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Am also 3.0.1
I had a couple of interesting incidents last night,
Had been flying around tweaking pids, x 4 battery's no problems
Sent it off on couple of missions which were ok
Then on next takeoff (on auto) it got to foot high and headed towards one of my club mates,
I flicked out of auto and did quick land, no damage
I pulled battery and reconnected
Next takeoff got foot off ground pirouetted really fast then flipped
I have no idea what problem is !
But thought you might like to know you are not alone !
I will also try compass and think I will recalibrate accelerometer
Great fun though !


     I think the issue with the copter pointing 15degrees off from the track is a 'feature'.  I suspect that you will find it's always point outwards and it will be worst for 90degree corners and much less for turns of only say 20 degrees or so.  The reason is that the copter turns to face the next waypoint slightly before it reaches the current waypoint.  This leads to slightly curved corners (which is good) but also leads to it facing in slightly the wrong direction.  I've created an issue here and we can try and sort it out for AC3.1.

     The compass interference shown in the tlogs is quite bad.  Maybe over 200%?  Not sure if you remember the value displayed at the end of the compassmot procedure.

The compass offsets for X and Y are also a bit large.  -150 ~ +150 is the acceptable range so X is over and Y is borderline.




By the way, I've improved the wiki a bit over the past week including an advanced compass set-up page.

By the way, there may be other things wrong as well to explain the more recent crash.  If you have a dataflash log that would be helpful.  I've also put together a wiki page here which talks about how to diagnose the most common problem.  I think 80% (or more) of people issues fall into one of the 6 issues mentioned.


Thanks a bunch for your help.  I really appreciate it!

Now that you've given me a clue I think I'll follow your write-up on the wiki pages and see if I can debug what's going on myself.  If I can't make any sense of the dataflash logs I'll pester you again.

What should I be looking for in dataflash, specifically?

Thanks again


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