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Drifts a lot in air after 1 green 1 red lights

Discussion in 'Phantom 2 Discussion' started by FlyingSam, Jun 22, 2014.

  1. FlyingSam

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    Hello, i take-off when having a green then a red light , it's almost 6 gps locks i guess . . but the phantom is really drifting so i should always drive in reverse od the air wich's a bit harder to control , so i dont feel it's confortable to fly with .

    Anyone experienced this drifting ? is there anyway to tune the phantom maybe ?
     
  2. bmw330vasilis

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    i have the same problem.I find 6 sat and after 1min found 9 sat but the lights still 1green i red and difficult to stay on air.No windy day...

    Στάλθηκε από το GT-I9505 μου χρησιμοποιώντας Tapatalk
     
  3. Happyflyer

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    Never guess on how many satellites you are connected to, know.
    Best to read and re-read the manual.
     
  4. sar104

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    The Naza holds position in GPS mode by reference to its GPS location. If the location fix is poor then it will drift. That is expected behavior.
     
  5. ianwood

    ianwood Taco Wrangler
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    Exactly. 1 red, 1 green is 5 satellites. That's not enough for a good level of precision. You should expect the P2 to drift and you should also expect it to move on it's own if and when it picks up more satellites and moves to the position it thinks it should be in.
     
  6. adanac

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    I think spellcheck must have intervened in a serious way in your post as there is much that is not readable.

    If you're talking about j-hook or right drift in forward flight (which I experience a lot) then it is an issue being worked on by people here and at DJI, whom we hope will release firmware at some point that will correct the issues.

    If you're talking about circling in place, known as toilet bowl effect (or TBE), then it can be down to the number of satellites you have and other issues. I often get that but find it stabilizes quickly.

    I will also typically wait until I get only green flashes and the 2nd set off rapid greens before lifting off.


     
  7. ElGuano

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    A couple of quick points.

    For blinks, one red, one green, in NAZA-M mode, should indicate 6 satellites found, not five. Six is the bare minimum needed to fly in GPS mode, and if it drops below this, you are in ATTI. Seven or more satellites found is green-only blinks.

    With respect to drifting, there is more than just the satellites at play. the Naza used to have a ~2 minute warm-up period, which allows the IMU to warm up and stabilize. After a lot of complaining from people about how it took too long to get in the air, DJI shortened and then eliminated the warm-up, so now you can take off very quickly, but the warm-up happens in the air. What this means is that for the first few minutes of flight, you may have a bit more drifting in GPS (or ATTI for that matter) mode until the IMU settles.

    The timing sometimes corresponds with number of satellites locked, so people tend to think GPS is the sole cause. This gets reinforced in multi-battery flights as the GPS can lock on much quicker on subsequent boots after the first power-up, so people see the satellite number jump up to 7-9 quickly on their second flight and note there's no drifting. The main cause though is that the IMU has already warmed to operating temperature from the previous flight.
     
  8. OI Photography

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    Do you know roughly when those progressive changes kicked in, or with what firmware? I hadn't picked up on that fact yet and I want to correlate that to other data I've tracked.
     
  9. ElGuano

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    IIRC, it was removed in 3.16 back in August, and the duration/limits were fiddled with a bit before then. There may have been tweaks in 3.18 but I don't recall exactly.

    One thing I try not to bring up to the P2 crowd is one of the early fw 1.0x changes that allowed for 35 degree tilt limits to a more aggressive 45 degree limit, I think it would be salt on the wounds :)
     
  10. ianwood

    ianwood Taco Wrangler
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    I stand corrected, 6 satellites. Either way, it's the bare minimum for an acceptable level of precision. This means some movement is going to be inevitable even as new satellites are acquired that improve the DOP. And if it is a matter of a semi-obscured horizon, GPS jumps will cause further movement as satellites add or drop when you move and the horizon changes.

    The IMU warm up makes sense and fits with my own experience. If I take off relatively quickly on a first flight of the day, the P2 will be a little less stable than normal. But, I've also seen plenty of movement on 2nd and 3rd flights due to limited satellites and/or changing horizon as per above.

    There is clearly a smoothing and/or averaging algorithm that handles sudden changes in lat/lon as result of jumps and DOP changes. The Phantom eases into it and starts slowly moving in one direction. And sometimes it's a little stronger. This weekend, I was filming a building in downtown. I did some passes in front of it. When I cleared it on one side it opened up a lot of horizon. That got my Phantom to thinking it needed to be further down the path and it took quite a bit of stick to coax it back. A little unnerving but fortunately only last for a few seconds at most.
     
  11. FlyingSam

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    Thank you for all your replies now it's more clear for me .. it's right it stops drifting after several minutes in air so the IMU warms up