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PROBLEM REPORT: Trim drift in mid-flight

Discussion in 'Phantom 2 Vision Discussion' started by LeoS, Jan 20, 2014.

  1. LeoS

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    So yesterday I made a bunch of short flights with my PV w/ a friend. We drove to one spot, fly it for 5-10 minutes, drive to another place, make short flights, etc) .. and on my 2nd or 3rd flight I experienced what seemed to be a trim-drift in mid air.

    (is that the correct term?)

    After accelerating along a 400ft straight line, I slowly countered the movement to stop then centered both of the sticks... the problem was that my Phantom continued to drift slowly forward even after making the complete stop. I tried to quickly confirm this condition by moving-centering my right stick a few times, and true enough the center seem to have drifted. So I flew back to home position and landed.

    I 'rebooted' the PV while keeping my transmitter and wifi repeater powered on, and it showed an MC error on the APP (MC Calibration Error - or some such. I forgot the wording). I thought I was screwed if I had to drive back home to recalibrate the whole thing with Phantom Assistant.

    As a last effort, I shut everything off (tx, repeater, pv) and repowered them back on. This time the problem went away.
     
  2. EyeUpHigh

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    Thumbs up for recognizing the problem and taking the conservative approach of bring the craft back in and diagnosing the problem. I've read so many flyaway stories that started with "the Phantom was behaving a bit oddly but I pushed onwards and then really weird stuff started happening"

    You could have been one of those people today but you chose a more prudent approach and now still own an intact Phantom. It's amazing what a simple power cycle / reboot can cure sometimes :)
     
  3. LeoS

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    @EyeUpHigh: Thanks! I can see that a trim drift can be really BAD if the pilot panics... especially if the craft is even further away to make out its orientation... and if you throw IOC home-lock\course-lock into the mix, I don't think I would be able to diagnose the problem right away!
     
  4. Pull_Up

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    Thanks for the heads-up on that one. Not seen any similar error myself, but I too would have landed straight away and power cycled as you did. If it had then continued to be off it would have been time to call it a day and head home.

    Have you plugged it into the Assistant since to see if everything is within limits? Worth doing an IMU calibration anyway, do you think?
     
  5. pault

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    I had this exact same problem yesterday (without the error message). I assumed it was a gps error. There is obviously a lot of damping/smoothing of the gps position and I know from the gps on my boat that sometimes errors can get through that overwhelm the smoothing algorithm. If you download an anchor watch alarm app to your phone you can see how the damping works. (I have not tried this but have read about it on a yachting forum).
     
  6. LeoS

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    Yeah, that was a pretty big surprise for me too. I was cautious for any unexpected movements too on the subsequent flights, but fortunately it didn't happen anymore.... kept me scratching my head.

    Thanks for the reminder, I've just connected my PV to the Phantom Assistant and the transmitter readout was almost spot on, except for +1 on yoke, which cleared up after quick recalibration.

    IMU checked ok 'no need to calibrate', but I went on with advanced calibration anyway, which curiously showed an 'IMU overheat' error... curious, since it's kept in a 23'C room. A repeat of it cleared the error. I'm gonna look for the thread mentioning this error.. I kind of suspect it's Phantom Assistant's issue...

    If it's a GPS error, it would probably keep pulling to the same position rather same direction (in relative to the phantom).
     
  7. Pull_Up

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    "Too hot" error is a known bug in the Assistant. Just click on through and it should allow you to proceed anyway if you get it in the future.
     
  8. LeoS

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    Thanks, I guess there's nothing wrong with my PV and it was just a glitch.

    Argh...
     
  9. pault

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    Maybe you are right, so I am not sure what caused it. I 'stopped' the PV2 when it was going forward slowly but instead of stopping completely it kept going forward for a second or two as though it was trying to get to a new position. It did not feel like momentum as it slowed down and then moved forward again. it did the same thing on a second battery half an hour later. It was nothing serious but certainly raised the heartbeat for a moment as I am so used to it behaving impeccably.
     
  10. LeoS

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    Oh that's curious, sort of similar to mine, except mine kept pulling forward wherever I moved.

    Certainly raised my heart rate and sweated while flying it back trying to make a soft landing... my right thumb got a decent workout :)

    I'll keep an eye on mine... will try to do sudden tilting motions to shake things up and see what happens.
     
  11. Scottrod

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    Pull up since you posted your video I find myself reading your posts with an English accent in my head. Lol. :)