I’d like to share my experience with my copter (aka ZuCopter) during my first full test using AUTO mode. My quad is ArduCopter, 3DRobotics Quad-C frame using APM 2.5 Firmware 2.9.1b

The plan was to go around the house, full automated, including takeoff and landing. This was executed quite smoothly at the first run J, Then I said… let’s try that again; I relaunched the same mission without turning the copter off or resetting, and…. something didn’t go so well: the quad decided to go full throttle without following strictly the programmed waypoints. I was good to have RTL mode programmed on my radio, so I was able to recover the flight back to manual mode.


This was the original plan:



The first run was quite well done I would say. Only thing I noticed is that arducopter do not strictly reach the altitude set at the waypoint. When it reaches the waypoint, it doesn’t matter if the altitude is lower, in contibue both increasing altitude and continue to the next waypoint.
From the data extraced from the LOG, you can see the waypoint altitude was reached only after waypoint 6.
Blu data are altitude requested by WayPoint Command, and the green is the barometric measurement.





This is the first run importing the .gpx information from the arducopter datalogger to Google earth.





As for the second run, I executed it using the same mission, without changing the mission nor switching off the quad. From the video you can see the strange behaviour:

  • Copter not heading straight (camera, which is the head of the copter, was instead on side)
  • Throttle-out was 100% most of the time during auto.
  • Waypoints were passed very large

Then I prefere to engage RTL to bring the copter back home.

This was the first run from another angle:




And this is the second run where you can see the different copter modes I set. The yellow below was the original AUTO mode, blue STABILIZE, red RTL





As you can see from the datalogger below, most of the yellow line (throttle-out) during the first part of the flight is set flat to 1000. So full motors.

The image below was merged to the mission mode sequence: yellow area is the lower graph is the AUTO MODE (graph below is gathered by importing to excel the logs and trying to align them as much as possibile to verify what happened in what mode; it is not perfect).


The last thing I do not understand, is:

  • why during the RTL the altitude decreased from 50mt to 10mt and I had to switch manual again to bring it back to a correct altitude?

I am attaching my log to this just in case somebody have any idea.


Overall I had quite fan, and was pretty happy I did program the RTL mode easy to be selected from my Radio switch.


2013-04-26 10-50 4-log.zip

2013-04-26 10-50 4_Analysis.xlsx

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  • Very nice controlling while things were bad. This is why dev work needs to  be done by one that knows how to fly manual. Love the way you recovered. 

  • That was scary. I don't see myself trying this anytime soon. I'll stick to manual flight. Great reaction and recovery. Seriously scary.

  • http://flyawayclub.com

  • Perhaps it was a combination of things. Some wrong altitude (why ever) lead to full throttle and a mag that is not shielded enough and disturbed by the full throttle impulse. The full throttle could even increase the vibration level and make things worse (ACC/GPS sensorfusion). But even with a disturbed mag and acc the arducopter code should see that the wp distance is rapidly increasing instead of decreasing. I don't know if the code doublechecks this. If not it would be an idea. Fight the increasing distance with a timeout (5sec?) -> battle lost for whatever reason -> Autoland, perhaps try a RTL for some seconds before (with the same check).

    Cheers Kraut Rob

  • Hi Chris, thanks for your suggestions. You are right, my arducopter layout is the one you described.

    I sow nowdays the newer Arducopter pictures have the APM on the upper Platform and now I undersand the resason :-).


    Do you think the interference were also the cause of the second mission wierd behaviour (full throttle, wrong waipoints....)?


  • 3D Robotics

    Great flight report! As for the orientation, the further you can get the APM from magnetic interference, the better it will perform. I suggest placing it on the upper platform (where you may have the GPS now) and moving the GPS to the side or elsewhere. That way you can get more distance from the power distribution board, which is a source of a lot of magnetic interference. 


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