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Hexacopter takes off on its own after arming

Posted by Chuck Devaney on May 19, 2013 at 8:57pm

So my hexa copter once I had armed it jumps up to about 500 feet, mills around a bit and did not respond to stick inputs very well.  It then took off and climbed to about 2000 ft and took a course that made it unable to follow.  It then came back with to fail safe, no assistance from the pilot and no rtl.   The entire time it was is stable mode.  I do not know the cause of any of this but perhaps some of you who have experienced fly aways could help.  I am open to questions and suggestions.

Chuck

2013-05-19 16-36 32.kmz

2013-05-19 16-36 32.log

2013-05-19 16-36 32.log.gpx

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  • Developer
    Randy June 20, 2013 at 2:52am

    Chuck,

           I've had a look at your logs.  As you say you're in stabilize mode the whole time and no failsafes are enabled so it's really all up to the pilot.

         It looks like you use radio contact from about line 4700 ~ 6900 but it appears you are mostly in control before and after.

    3692750226?profile=original     I say "mostly" because if you check the graph below you can see that the copter loses roll control around line 3000.  This looks like a mechanical issue.  I say that because the copter wants to maintain a mostly level roll ("Roll In") but it isn't able to ("Roll").  If it were a software issue then both lines would continue to track but they would both be crazy.  That's not the case here though..the copter wants to maintain a good attitude but the frame won't respond properly.

         The copter again loses roll control just before it loses radio contact at about 4600.  Again it looks like a mechanical issue although the throttle is quite low (20% ~ 30%) so perhaps it's partially because of the turbulence as the copter falls through it's own prop wash.

    3692750389?profile=original      When you lose radio contact the copter is already at 150m (450feet-ish).  It's unclear if you commanded a 60% throttle just before losing radio contact or if the tx/rx failsafe is set-up so the throttle moves to 60% upon loss of contact.  Maybe you can check by turning off your transmitter while the copter is on the ground with the battery disconnected and see in the mission planner by looking at the failsafe screen.

         None of the battery or throttle failsafes were set-up so I believe you just got lucky and the wind blew the copter back to you and you were then able to retake control.  It looks like when you got back control you also reduce the throttle but the copter was already coming back down, probably because the battery was getting weak.

         By the way, I suspect your copter has quite bad vibration.  I think you should enable the RAW message (or IMU if you switch to 3.0) so we can see how bad it is before you try alt hold.

         Congrats on getting your copter back.  It's mostly down to just good luck.

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