Crash, please help

Discussion in 'Electronics' started by Emanuele Chiocchio, Feb 28, 2013.

  1. Emanuele Chiocchio

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    After many months of perfect flights, it seems we too had to have our doom. No one was injuried cause we always fly without people underneath but our copter suffered some damages (it was a test flight - recovered the most parts). Good news is that we're building another one just now but we would like to know what happened or understand our mistakes. We run on MK electronics and they're covered with a plastic dome; we do not rely on automatic or semi-automatic functions; always manual control.

    From what we can understand reading the log, the main cause is (should be) a motor failure.

    Any help would be really appreciated, especially now: we're considering DJI electronics over MK.

    Attached is the GPX file.


    Ciao!
     

    Attached Files:

  2. Steve Maller

    Steve Maller UAV Grief Counselor

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    I'm no GPX file expert, but I see something alarming, in that motor #1 all of a sudden starts pulling way more power than the others. Not sure if that's the one that failed, or if you can even tell. But 10 seconds or so before the errors appear in the log, the power shifts pretty dramatically. See the numbers in red...

    84,78,68,62,78,69,111,32,0,0,0,0
    84,78,68,62,78,69,88,31,0,0,0,0
    84,78,68,62,78,69,88,31,0,0,0,0
    87,88,68,62,78,69,88,31,0,0,0,0
    87,88,76,71,71,69,88,31,0,0,0,0
    87,88,76,71,71,62,73,34,0,0,0,0
    87,88,76,71,71,62,73,34,0,0,0,0
    119,88,76,71,71,62,73,34,0,0,0,0
    119,75,85,41,71,62,73,34,0,0,0,0
    119,75,85,41,75,50,86,34,0,0,0,0
    119,75,85,41,75,50,86,36,0,0,0,0
    119,75,85,41,75,50,86,36,0,0,0,0
    106,90,74,41,75,50,86,36,0,0,0,0
    106,90,74,49,56,59,86,36,0,0,0,0
    106,90,74,49,56,59,74,41,0,0,0,0
    106,90,74,49,56,59,74,41,0,0,0,0
    102,76,74,49,56,59,74,41,0,0,0,0
    102,76,70,38,58,59,74,41,0,0,0,0
    102,76,70,38,58,47,81,29,0,0,0,0
    102,76,70,38,58,47,81,29,0,0,0,0 <-- GPX file errors begin here
    118,39,70,38,58,47,81,29,0,0,0,0
    118,39,126,158,58,47,81,29,0,0,0,0
     
  3. Emanuele Chiocchio

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    Tnx Steve. We're no GPX experts too but we've noticed the same. We're concerned to find the real problem here: if it's our fault or not...
     
  4. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    Sorry, don't have time this morning to look at the GPX file, but what "GPX file errors" are you referring to Steve?

    Andy.
     
  5. Gary Haynes

    Gary Haynes Administrator
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    Emanuele

    Some observations of your GPX file.

    1. Looks pretty normal until about the 30 second point where there is a significant spike in watts being pulled. Jumps from about 1100w average to 1400w. Then starts to decline until 62 seconds where it climbs back to 1400w in 2 seconds and the recording ends.
    2. Throttle was pretty consistent until the 62 second mark when it jumped to nearly full throttle (63 second) and then zero throttle at 64 seconds and then the recording ends.
    3. At 62 seconds you got a low voltage warning for 15.7 volts. What are you flying for batteries?
    4. At 64 seconds you got a Error 023 which is Motor Restart a) one BL Controller tries to restart the motor or b) motor blocked or defective motor cable. Do you see any damage to any of the BL's like melting or a blown MOSFET or other IC?
    5. You compass readings have a wide variance on many of the data lines. Example ad 5 seconds the values are 123,243. Have you done a compass calibration? Was there a significant amount of iron in the location that you were flying?

    Can you share any more information about what you saw during the flight? Any videos? Windy? Copter setup, motors, props, weights?

    Suspects would be a BL that failed.
     
  6. Emanuele Chiocchio

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    Hi Gary,

    the flight was perfect and we were slowly descending. All of a sudden, the copter lost control completely: it pitched about 90°. We're using Quadrocopter 5S 6200mAh (excellent LiPos) and they were fully charged. I don't think there's a significant amount of iron in the place we were doing our test. Compass was calibrated the day before (same place) successfully.

    The copter is (was) a default Cinestar 8. Absolutely no wind or difficult weather conditions whatsoever.

    Even if a BL/motor failed, we choose the 8 for its redundancy.


     
  7. Howard Dapp

    Howard Dapp Active Member

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    Unfortunately with MK electronics there is no redundancy when an ESC fails in flight....It knocks out the entire i2c bus shutting down all motors. There's only redundancy when a single motor or prop fails.
     
  8. Ben Freedman

    Ben Freedman Member

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    Not sure that's quite true. We've had a BL fail in flight and just shut down one motor. It probably depends on how it fails... Some sort of direct short would probably knock them all out, but our last BL failure just took out one, and the heli kept flying...

    Just food for thought...

    B.
     
  9. Howard Dapp

    Howard Dapp Active Member

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    Thanks for the correction Ben. Yes, true, depending on the type of failure. Maybe I should have stated if an MK ESC loses power (wire snaps or disco'd) or an ESCs i2c connection is damaged or becomes disco'd it'll knock out the 12c bus.
     

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