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DJI Phantom 2 Vision + flyaways .... Explained & Resolved

Discussion in 'Phantom 2 Vision Discussion' started by maakx, May 19, 2014.

  1. maakx

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    Watch this youtube very plausible explanation for the flyaways.
    [youtube]https://www.youtube.com/watch?v=_ge3GuhEDRM&feature=youtu.be[/youtube]
     
  2. Mal_PV2_Ireland

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    Re: DJI Phantom 2 Vision + flyaways .... Explained & Resolve

    Its just a theory with no proof.
     
  3. Pull_Up

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    Re: DJI Phantom 2 Vision + flyaways .... Explained & Resolve

    Please note that I say all the following with absolutely no technical qualification - but it doesn't stop almost everyone else on the internet so why should it stop me?! ;)

    As far as I'm aware the GPS in the phantom (or your car satnav or handheld, whatever) doesn't work like your phone. Your location on the phone is first determined very coarsely using the data it has about which cell towers it can see, and so triangulates a rough position whilst waiting for the longer process of getting a satellite lock. If you're in an area covered by Street View then it can also use wifi SSIDs it collected to help narrow it as well. This is why Maps works even if you have GPS switched off in your settings, but why the accuracy is not very good (perhaps only within severl hundred metres, sometimes worse). Once the phone's on-board GPS has sufficient satellite lock for it to calculate your position (usually 4 sats as a minimum I believe) it then takes over the position data and that's why the accuracy circle goes from many tens of metres or more to only a couple.

    In the Phantom and other non-phone applications of GPS it doesn't have access to any other information like cell towers or SSIDs so there can't be a way it could use such relatively inaccurate data. Once it has the minimum number of good sat locks to triangulate a position it should be within a handful of metres, getting more more accurate as more sats are added to the picture.
     
  4. Dalite

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    Re: DJI Phantom 2 Vision + flyaways .... Explained & Resolve

    The more likely cause is a gps glitch during flight that forces reacquisition of satellite data, and the data accuracy improves with each sat acquired.

    However, the NAZA does not have the error checking necessary to sense an impossible variance in position data between one timer tic to another and over rides all attempts at external control as it heads toward the first fix; with the largest margin of error.

    Anything that invokes a Fail Safe or similar autonomous routine from the NAZA severely limits control if the Phantom is left in GPS mode.

    As long as there is a good link from controller to Phantom receiver, Manual mode seems the best way to overcome the firmware oversights.

    It is like comparing Basic to Machine Language in the field of Computer Programming.

    The more overhead in the compiler ( to make the programming language more user friendly ), the higher margin for error and unresolved conflicts. In the Phantom, what makes it easier to fly for the consumer, also makes it harder to control when an unresolved conflict is accepted as valid data by the flight controller.
     
  5. bobomet

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    Re: DJI Phantom 2 Vision + flyaways .... Explained & Resolve

    It seems there is an exponential increase in the chance there will be a GPS disturbance, and resulting "flyaway", as population density increases.
    But not to worry ....
    By 2016, in the USA, you'll have access to many (some military) satellites in exchange for a commercial registration and annual fee.
    In addition to the fee, you'll need to install a transponder to be FAA/NTSB compliant, and it'll have to be on whenever you're in the air.
    For the hobbyists .... I hope you'll like flying in your own backyard. But the good news is you'll never get lost.
     
  6. John Shaw

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    Re: DJI Phantom 2 Vision + flyaways .... Explained & Resolve

    Just a couple of comments after watching the initially referenced video. It was logical and thorough but we must consider...
    1. There were fly aways before the fairly recent addition of the range and altitude limit for the Vision.
    2. The Phantom doesn't log a home point until it has at least 6 satellites probably to protect against this type of problem. Your cell phone makes a guess as soon as it can and you can just sit there and watch it improve the estimates.
    3. It would seem if this were true the instant you lifted off the Phantom would immediately head toward the erroneous home point and since it is not a RTH it wouldn't climb to 66 feet. This would be get your attention immediately. The manual says you can still control the Phantom except to fly it further away (from the erroneously referenced home point). Therefore you should be able to stop it's motion and land it. Most fly aways don't seem to happen this way.
    None the less it is food for thought.
     
  7. Monte55

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    Re: DJI Phantom 2 Vision + flyaways .... Explained & Resolve

    couldn't one verify there home position by going out a ways and go to home lock and pull the right stick back. If if comes back to home point, you're good. If it heads off in another direction, then it thinks home is elsewhere.
     
  8. jetdust

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    Re: DJI Phantom 2 Vision + flyaways .... Explained & Resolve

    Every flight I fly out a bit and flip off the controller to make darn sure that the home lock is set. I also wait for the quick flashing green and check satellites to make sure there are 6+... Things happen but this is my cheap insurance plan...
     
  9. Happyflyer

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    Re: DJI Phantom 2 Vision + flyaways .... Explained & Resolve

    Monte55 had the same thought I had when watching that video. Just check it after you take off. Sounds like a good idea.
    :idea: