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Please Help: Fly Away. I suspect vibration but need help analyzing telemetry

Posted by Dennison on September 22, 2016 at 11:04am

Hi, I am running Arducopter version  3.3.3 on a pixhawk v2 using a 3DR external compass/mag and a spektrum DXE 6 channel rx.  I have a dji 550 clone running two multistar 3s 5200mah 10c batteries in parallel.  I am using this uas to properly familiarize myself with operating a uav platform for my eventual remote sensing small business.  I recently flew it without a ground control station trying to calculate my maximum flight times before moving on to test some of the autopilot features and operating my sensors at altitude.  I have been battling vibration issues since getting into this business because my test copter is a relatively cheap uas vs the other one i plan on eventually using.  I have some cheap chinese RHD B2212-920kv motors with "mystery M-30" 30A Escs.  DJI 1047 props.   I have balanced the props but have been unsuccessful at balancing the motors mostly because I lack the time at the moment to give it the patience it takes to balance them.  

Anyways back to the current problem.  I was flying when i suddenly lost control of the uas, the pixhawk started flashing yellow and steadily beeping at me as it flew straight up.  I cycled my transmitter thinking it was a lost radio connection (even though I was standing within 10ft of the copter) and switched over to a failsafe flightmode.  I regained some control of the copter and landed it on the ground.  I have had trouble with vibration as i've said before, but I didnt get any toiletbowling, just a flyaway and twitchy flying.  Since I didnt have telemetry from that flight and I"m too afraid to take it out and risk another fly away, I strapped in to a table in my shop and tried to recreate the problem.  Low and behold, I got the same result.  The attached telemetry is from that flight.  Please help

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Tags: away, fly, flyaway, help, telemetry
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Replies

  • Dennison September 27, 2016 at 2:34pm
    Ok I've seen some contradictory posts on here. thank you for clearing that up for me. I appreciate that.

    Im going to try and be a little more active on the forums here so people can get to know me.
    find my look-a-like, my face double, doppelganger or my face match
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  • matt.koestner September 27, 2016 at 8:13am

    Hey sorry for the slow reply but you will need to cut all of the ESC BEC power wires if you will be using an external BEC to supply +5V to the servo rail.  Alternatively use 1 ESC BEC and cut the rest of them.

    Dennison said:

    That's good to hear. I'll try and stumble through autotuning it next time I fly. My other build is a 830mm cf frame. 330kv t-motors. 15-6 xoar electric props. And 15,600mah 6s battery bank. (Using 3 sets in parallel of two 3s batteries wired in series). I'm excited to get it flying but don't want to end up crashing it before I learn the systems.

    While I have your ear, can you settle something for me? I'm still confused on the red wire from a bec esc. Clip or no clip? I'll be having backup power supplied through the aux rail, so what is the actual way to wire the ESCs?
  • Dennison September 23, 2016 at 5:45am
    It hit the low voltage failsafe and went into RTL. My RTL altitude was set at 15m. Since I'm still a beginner and haven't experienced that before, I thought it was a fly away.
  • Michael Burmeister September 23, 2016 at 3:32am

    Neither log shows any fly away and the vibrations look good.  These logs are from the 14th and 15th with no issues.  I suspect they are the wrong logs.

  • Dennison September 22, 2016 at 9:40pm
    That's good to hear. I'll try and stumble through autotuning it next time I fly. My other build is a 830mm cf frame. 330kv t-motors. 15-6 xoar electric props. And 15,600mah 6s battery bank. (Using 3 sets in parallel of two 3s batteries wired in series). I'm excited to get it flying but don't want to end up crashing it before I learn the systems.

    While I have your ear, can you settle something for me? I'm still confused on the red wire from a bec esc. Clip or no clip? I'll be having backup power supplied through the aux rail, so what is the actual way to wire the ESCs?
  • matt.koestner September 22, 2016 at 6:41pm

    Hah no worries!  I'm at work, so plenty of time to do other stuff :-)

    Once you get it tuned you will be amazed at how much wind it will handle.  I have almost the same build and regularly fly it in 20-30 MPH winds, snow storms, whatever.

    Yeah lots of the documentation is poor or wrong for the RC components.  

  • Dennison September 22, 2016 at 2:32pm
    Oh and it was slightly breezy; maybe 5mph gusts? I try to fly when the winds are under 7mph gusts until I get everything running smoothly and I am more comfortable flying.

    I know a lot about remote sensing, GIS, and traditional aircraft. I have a degree in GIS and I was a C-17 Loadmaster in the Air Force, but I have no experience with R/C crafts. I'm really confused when it comes to the transmitters but I've got the DXE to at least work for me. I'll probably be on here a lot when I try integrating my recovery system though.
  • Dennison September 22, 2016 at 2:26pm
    This is great! Thank yo so much. I have not done an autotune yet, but was reading up on it recently. I am still having what seems to be beginner issues that should probably be addressed first.

    Thank you so much for the detailed replies. I'm sorry I'm short with mine. I am replying when my 2 year old gives me a short break. Haha
  • matt.koestner September 22, 2016 at 2:03pm

    Awesome!  If you open log ending in 18-26 look around timestamp 67441 you can see when battery voltage falls below ~10.7V, RTL engages.  Your battery failsafe is set to 10.7V which is OK, maybe a bit conservative but it really depends on temperature and the battery pack.  I also noticed the starting voltage was 11.8V or so, this may be the 2nd flight of the session so that might be OK.  FWIW a full 3S should be 12.6V.

    http://ardupilot.org/copter/docs/common-diagnosing-problems-using-l...

    If you haven't read this yet, it has some helpful info.  Your vibrations look pretty good, so I think you are OK there.  

    Your RTL altitude is set to 15m so tweak that if need be.

    Have you run auto tune?  There are some places in the log where pitch and desired pitch fairly strongly diverge.  It maybe super windy out or your tune might not be optimal.

    Diagnosing problems using Logs — Copter documentation
  • Dennison September 22, 2016 at 1:29pm

    .

    2016-09-15 22-06-32.bin

    2016-09-14 19-18-26.bin

    https://storage.ning.com/topology/rest/1.0/file/get/3702303172?profile=original
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