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P4 disconnected in flight, found with battery missing

Discussion in 'Phantom 4 Help' started by WBN3, Dec 28, 2016.

  1. WBN3

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    Wow, that's interesting analysis... I just wonder if the flight controls were some way confused being at the boundary of the authorized zone. The log entries that I saw seemed to bounce back and forth like it was arguing with itself about what to do. That's an over-simplification, but my concern all along has been that the software didn't perform as we understood it should.

    When my son commanded a RTH, since the direction it turned was away from the authorized flight zone, I could see no reason for it to hesitate. It appeared to begin gaining altitude, then went back on its downward path and disconnected. The fact that it hovered at 20 meters for some time then began descending again is odd. Could the last little bit of time where the voltages went nuts been it coming into contact with a tree? In Google Earth 3D, the last elevation was close enough to the height of trees in the vicinity that it wouldn't surprise me. I know the 3D render is just an approximation based on the aerial photos it has available, so trees could've been taller, and altitude wouldn't be precise enough to exclude that possibility.

    Thanks for your efforts on this... we are not yet ready to test fly the P4 after this. I am pretty sure the firmware is in need of updating, so if anyone has words of advice or warning about which version to avoid, would appreciate that as well as feedback on DJI Go vs. DJI Go 4.
     
  2. BudWalker

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    Good question .Looking at the accelerometer and gyro data it does appear to have hit something.
    upload_2017-2-17_7-55-22.png
    upload_2017-2-17_7-55-28.png
    upload_2017-2-17_7-55-34.png
     
  3. BudWalker

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    And looking at the motor data it appears the props (particularly the the right back) got caught in something.
    upload_2017-2-17_8-0-26.png

    upload_2017-2-17_8-0-35.png
    upload_2017-2-17_8-0-44.png
     
  4. WBN3

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    The forensic capabilities of the .dat files is really something else. I have little doubt that the bird got caught in a tree top... my concern now is strictly with HOW it ended up getting there after being told to RTH. I'm reluctant to go flying again (or let my son go flying again) until I understand that better.
     
  5. WBN3

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    Just to close out this thread...my son has successfully flown the P4 since we received it back. The only issue we had was the battery which was ruined when it fell into the ditch. There were no performance issues with the drone at all.

    As to the cause of the incident, I am going to presume it had to do with the control system not being up-to-date. When I connected to DJI Assistant, it needed to be updated on firmware, as did the remote control. At the time of the incident (Dec. 2016), the bird had V01.02.0503 (where latest was V01.02.0602 - Nov. 2016 release) and the RC had 1.6.0 (where latest was 1.8.0 - Oct. 2016 release). I don't know if either or both of these factored into the unexpected behavior, but we have learned from the experience.

    1. Always verify the firmware is up-to-date (or at least not incredibly outdated - maybe hold off on updates by a month)
    2. Always maintain VLOS
    3. Always stay away from flight region boundaries where drift or GPS issues could trick the system into thinking it was somewhere it wasn't supposed to be
     
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