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My turn to crash (video)

Discussion in 'Phantom 2 Vision + Help' started by burritocmdr, Jul 15, 2015.

  1. burritocmdr

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    Had my P2V+ for almost a year, didn't fly it very much but I was just getting comfortable flying it... and then I had my first crash. After 15 mins of good flying I wanted to bring it in and land. About 30' in the air, suddenly I lose control and it comes down hard. It didn't appear to lose all power. The rotors were still turning with power and I certainly had plenty of battery left. A guy who seemed knowledgable about Phantoms was watching and saw it happen, he came over and said it looked like a "not a number" error. Don't know what he meant by that. Any idea what happened here?

    Physically, nothing looks damaged, but the gimbal goes a little crazy when I fire it up now. The ribbon connector looks good. All four rotors rotate seemingly without any problem. Is this self-repairable, or does it look like I'll have to send it in for repairs? I'm probably over the warranty by now which really stinks.

    Video of the crash:


    Gimbal failure:


    Thanks!
     
  2. Ken Cruise

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    That is strange about the gimbals. I still have not figured out why the gimbal on my 1st P3 went crazy after my crash.



    The ribbon cable looked fine but I didn't open mine up just sent it off because the case was damaged. Would like to know what causes that after a crash
     
  3. Mako79

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    For stabilisation, each of the axis need to be perfect. If 1 is out, then all is out it will never initiate correctly. In each gimbal motor is a potentiometer (sensor) that registers a value between (let's say) -1000 to 1000. On a dead flat surface, the 3 axis should register 0 on all 3 potentiometers. Now if the phantom tilts, it would tell the gimbal control board to compensate by giving the motors a value.

    On a crash, you may damage the potentiometers, mis-align the D shaft or even bend it, or even tear or damage the ribbon cable. If the pots are damaged, it would send random numbers to the gimbal board.

    The fix (maybe).
    The first thing to try is to find the hex screw (op side of the ribbon cable) at the beam of the gimbal near the yaw motor. Loosen it and move it so there is no obstruction and then tighten.
     
  4. RoyVa

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    Looks like hardware damage. It is repairable but most likely by someone with experience. Internal problems with the potentiometers or bent shaft most likely. Not for the novice to repair. Can be up to $300 to fix.

    Never heard of what the other guy told you about the error.

    Were you holding the left stick down?
     
  5. marg2

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    Take the lens cover before turning it on
     
  6. marg2

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    Take off the lens cover before turning it on that will help
     
  7. burritocmdr

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    Taking the lens cap off didn't make a difference. Thanks for catching that though.

    I just noticed that the gyro arm about the roll axis feels a bit loose. I think it should be tighter than it is. I may try and take it apart and check it out.
     
  8. Nerius

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    My had very similar crash, reason still unknown:
     
  9. Frogbone

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    Ummm, why is there sound with your video? Am I missing something? My videos never have sound.....

    Ready for an answer that will embarrass me, lol....
     
  10. Nerius

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    Sound and color grading added by me in post-processing ;)
     
  11. yorlik

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    how? did you have an audio recorder on the quad? It has a couple distinct "kicks" in the sound before the crash.

    Are those creative editing or somehow real from this flight? If real, again, how? We would all love to know how to get this sound! If real, it would give us all a LOT more info of what happens just before crash!

    Please share how you do this!!
     
  12. Nerius

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    As I wrote before, sound and color grading added by me, in post-production, using Final Cut Pro X: it's not from the real flight and I don't have any audio recorder on quad. Just thought: if I had a crash, why not to make a short movie from it ;) .
    This is how video timeline looks on FCPX (green lower strips are sound effects):
    Screenshot 2015-07-20 08.39.50.png

    To make things more clear, this is how video looks unmodified, straight from the Phantom camera (made it a little longer):


    Short story about this crash:
    Tested new antenna mod, Phantom lost connection, started return home (attitude 30m, about 90 feet) fly back about 100 meters (300 feet) and suddenly this happens. Maybe one of the motors or ESC malfunction: stopped or started to spin at lower rpm ? But as we can see in video, that it suddenly lost stabilization, then stabilizes and started quick descending: so motors still running, maybe at lower rpm. Phantom hard landed about 700m away (±2000 feet) and in wheat field so it was troubling to find it. When I finally found it all props were still running, but entangled in a wheat straws, a lot of heats generated, so body shell plastic near motors melted. Replaced body shell, all ESC and motors.

    Posted this video, because @burritocmdr crash video looks very similar for me: bird lost stabilization, then stabilizes and quickly descended. Maybe it will help find both crashes reason.
     
  13. yorlik

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    thanks for clarifying - again. I should have paid better attention to your details!

    It does bring up the ever more happening motors not shutting down and melting the case.

    I wonder why dji doesn't fix this? It would be so simple to do! It should be done in the esc board itself, but that would require new firmware and I don't think they can do that without replacing the board. But it also could be done in the std ol fw updates they send out - like 3.08 or 3.14... they could VERY EASILY add a current foldback I^2t to the command pwm going to each esc board. Yes, they do not monitor actual current, but they send a command for current, so they know they are sending over current command for a LONG TIME and melting the case. Simple algorithm that is in 100% of all good servo controls.
     
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