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P3 drift and crash

Discussion in 'Pro/Adv Discussion' started by marzipana, Jan 9, 2016.

  1. marzipana

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    Hi, I'm new here, this is my first post. I recently got a P3 Advanced - read instructions and viewed as many videos as I could and have been flying very slowly and tentatively this past week. Before ever flying for the first time, I charged the batteries in both the drone and the RC and then downloaded and installed the latest firmware.

    Yesterday evening I took the P3 to the local golf course, and all was going well (very slow flying and altitude no higher than 12.4m according to my flight log.) All of a sudden, it started drifting to the left and picking up speed - it wasn't until I checked the flight log that I noticed it had suddenly jumped from P-GPS to P-OPTI and that's when it started moving fairly quickly (5.5 m/s) to the left.

    Prior to the flight, I had done the compass calibration on it and it said it was safe to fly. There was minimal interaction with the RC on my part (I think I panicked and didn't want to use the right stick in case I made it worse) so this flying away was purely the P3.

    Anyway it lodged in a tree, very high, and I managed to dislodge it by moving the RC sticks - it did come free but plummeted straight to the ground and into a massive thicket of blackberry bushes, which covered a large area. I had to come back home and return with a hedge trimmer and had to literally cut my way towards it.

    I managed to retrieve it - it had a snapped propeller and has some scratches and scuffs but thankfully the camera and gimbal seem okay.

    I hadn't done an IMU calibration after the new firmware as I didn't become aware of this until after this disaster and some Googling - could this be at fault? I've since done that and the RC controller as well.

    Is it normal to go into P-Opti outdoors? I thought that was for indoors? I noticed after performing the IMU calibration that Vision Positioning System seemed to be on by default - I've never switched it on. I have since switched it off. Should it be on or off for outdoor flights?

    It has really shaken my confidence. I calibrated the drone on the putting green, no buildings or trees or metal close by...it was frightening that it just took off on its own. So I guess I'm just wondering if anyone knows what might have caused this?

    Thanks in advance,
    Tamara[​IMG]









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  2. ScopeTech

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    So now, following the latest firmware fix for recent battery issues, we're starting to see Phantoms 'popping' out of one mode to another.
     
  3. msinger

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    If you post the TXT flight log from your mobile device, we can take a look and see if there are any hints as to what might have happened. If you're not sure how to find that TXT file, then see the instructions beneath the gray upload box here.
     
  4. Meta4

    Meta4 Moderator
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    Hi Tamara .. that's good that you recovered your bird intact but disappointing that the cause isn't easily seen.
    It proves that blackberry thickets aren't all bad after all.
    It's a bit puzzling but the problem is likely to be related to switching into P-opti.
    Disabling the VPS is probably a good idea, it doesn't do anything critical for most flight anyway.

    Just checking ... did you calibrate the IMU somewhere on a perfectly level surface? (indoors is OK for IMU)
    After a bit of a shake-up, it's a good idea to do the IMU calibration again.
    Take it out again, keep clear of trees and see how you go with VPS off.

    And as msinger says .. we might be able to see a little more in the flight log.
     
  5. Meta4

    Meta4 Moderator
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    A sample size of one isn't enough to draw any conclusions.
    There are all kinds of possible causes so locking onto one in particular with no evidence to back it up would be unwise.
     
  6. marzipana

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    Thanks everyone - just to answer Meta4, since getting the drone, I hadn't done any IMU calibration until AFTER this incident - I wasn't aware it was something I needed to do, I don't recall seeing any instructions to do this with the DJI tutorials before first flights.

    Anyway, have uploaded the log -
    HealthyDrones.com - Innovative flight data analysis that matters
     
  7. msinger

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    Please upload the TXT file here.
     
  8. marzipana

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    Uploading now...
     

    Attached Files:

  9. msinger

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    Your log shows you were flying in ATTI mode the entire time. That means your PAF switch was set to the "A" position (according to the log). It looks like you drifted into the trees since GPS was not being used to hold your position.
     
  10. Meta4

    Meta4 Moderator
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    Looks like msinger spotted things first. Drifting in atti would explain things.
    For anyone looking at it, it looks like the motor obstructed warnings from 3:48 are when you had it stuck in the small branches - everything after that is not flying.
    Some users like to calibrate the IMU after updates but I wouldn't be concerned about that.
    I only asked because it wasn't clear what calibrations you did on the putting green.
    I would give it a new IMU calibration though, now after the fall as it can shake things up.
     
  11. marzipana

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    And yet the visual flight record (and what I saw on my iPhone whilst flying) tells me that I was flying in P-GPS mode, and then P-OPTI when it took off. I just checked the controller and the switch is on P, not A - I haven't touched this switch since getting the P3....?!! I'm confused now.


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  12. Rumbaar

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    I had something similar today, I went driving out to the bush and found an openish area. Did my normal start up, and calibrated the compass due to vastly new area. All checked out. Started up and flew up to about 15-20m and then my Go App started displaying red compass errors, and warnings. The drone started to drift forward, I manually corrected the drift and landed the drone immediately. Performed a calibration again, and it seemed to function correctly from then on.

    I looked at my logs after the flight, and do not notice it reflecting the errors the app was showing me.
     
  13. marzipana

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    The calibration I did on the green was the copter itself - the 360 degree horizontally and vertically.


    Sent from my iPhone using PhantomPilots mobile app
     
  14. marzipana

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    Msinger, if you look at the image I posted of the flight record at the top of this thread, you'll see what I saw on my phone, it does say P-GPS, not Atti mode. How can this be different from the text file I uploaded?


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  15. Meta4

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    Not really related to the incident in this thread.
    That sounds almost certainly like an issue caused by calibrating the compass in an inappropriate area. - or you flew close to a lot of steel.
    Where did the flightlog show P-Opti mode?
    Was it when the Phantom was close enough to the trees that it might have had leaves close beneath it.
     
  16. marzipana

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    It changed to P-Opti right before it took off to the left while I was still far away from the trees. [​IMG]


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  17. Rumbaar

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    I was in the bush, no steel there and I re-calibrated in the same spot after the initial issue. But I'll not thread-jack this thread. Just sounded similar as it shifted out of P GPS assisted mode on it's own and started to drift.
     
  18. marzipana

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    Btw, when first starting it up and waiting for the safe to fly signal, I've often heard it say Atti mode during this start up time, even though I've never physically touched the switch on the controller, it's been on P since I pulled it out of the box.


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  19. Rumbaar

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    I think it shifts to the mode when it doesn't have enough GPS satellites or compass issues?
     
  20. With The Birds

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    Sorry to learn you ended up in the srub but sounds like you will be up flying again in no time.

    From the log it seems you had your work cut out for you and were unlikely to be getting much assistance from the phantom in flight.

    LOG shows poor GPS signal on a number of occasions.

    Aroumd four minutes in compass performance was reported as very poor also.

    As to the vision positioning system you were two high off the deck for it to help,.

    Replace the props and take it slow and gentle. Maybe in a new location for the next flight