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Hovering on own.

Discussion in 'Pro/Adv Discussion' started by budzy, Feb 17, 2016.

  1. budzy

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    As I have a Phantom 3 Adv. I have another smaller much cheaper one. I am really impressed with my Phantom but was wondering since it is able to just hover as I let go of the controls is this due to have a GPS? As when I look at other makes, how would you know if it could do the same. Thanks.
     
  2. m0j0

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    GPS is why it hovers in place. There are other options that also use GPS.
     
  3. Meta4

    Meta4 Moderator
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    The GPS is only one of about a dozen sensors that the P3 uses to do what it does.
    The Phantom also has a barometer to give its altitude input.
    GPS doesn't give it the stable hovering that you notice though.
    That is mostly due to the accellerometers in the IMU that detect movement in 3 axes.
    If it was just GPS, the Phantom would wander 1.5-2 metres horizontally and the height would be all over the place..
     
  4. budzy

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    So if I wanted to get a cheaper one for grandson what would the description say for me to know it can also hover? As I feel this is a great thing t enjoy flying and safety. Thanks
     
  5. With The Birds

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    Given Meta4's explanation above, ie that the IMU and barometer provide for the ability to maintain stable hover (which makes sense) I wonder if DJI could implement a firmware change to avoid the panic and crash on GPS lost outcome. The frequency of inexperienced operators coming to grief when they loose GPS hold and drift away in the breeze is not insignificant.

    If your flying in P-GPS mode your intent is likely to maintain position hold. Why not keep the IMU active on GPS loss and leave the freedom of drift to ATTI.
     
    Blippin likes this.
  6. marzipana

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    If you look for something with "altitude hold", I think that's what you're after. Hubsan make great little quads and they have one with this feature:

    Hubsan X4 Plus H107C+ RC Quadcopter Drone 2.4G w/ 720p HD Camera Altitude Mode


    Sent from my iPhone using PhantomPilots mobile app
     
  7. Meta4

    Meta4 Moderator
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    With GPS active, a hovering Phantom acts like it's attached to a point on the ground.
    But in atti, all sensors except GPS ate still working and with hands off the sticks it's now acting like it's attached to the piece of air around it.
    But if the air is moving (breeze) there's no way for the sensors to maintain position relative to a fixed point so it can drift with the wind.
     
  8. With The Birds

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    I will have to think about this Meta4. Im not saying i disagree however i need to get my head around it. If the imu is informing the flight controller of an acceleration vector, which no doubt it is caoable of, when the phantom wss first acted on by wind it should be caoable flying against the applied force to maintain its position (apply power to the rotors as required to keep acceleration at zero.
     
  9. alokbhargava

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    The reason for drifting away could be due to two reasons: GPS not available or compass error.

    For GPS loss it doesn't know its position and for compass error it can not move in the correct direction.
     
  10. With The Birds

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    Compass will give heading rather than direction. Agreed GPS provides input used to maintain position in hover. Qustion is can IMU data alone provide enough data to hold position?