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What is the algorithm/logic behind DJI's RTH?

Discussion in 'General Discussion' started by un hombre, Sep 25, 2014.

  1. un hombre

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    Location:
    Ireland - Poland
    Let's assume this situation, we have a point A, ridge, 100 meters above sea level and point B, plateau, 10 meters above sea level:

    A
    *
    -------------------|
    -------------------|
    -------------------|
    -------------------|
    -------------------|
    -------------------|
    -------------------|------------------------------------------* B

    Point A is where I am standing and this is the drone's Home position. Point B is drone's current GPS position, however say 5 meters over the ground it is flying above.

    Now, what happens, if I switch Drone to RTH?

    Will it:

    1) Increase the altitude to 15-20 meters above position b, fly towards position A and crash somewhere in the 1/3th of the cliff's height, or
    2) Increase the altitude to 15-20 meters above position b, fly towards position A and somewhere before the cliff starts it will increase the altitude to around 120 meters above sea level, so that it is around 20 meters above position A, when it gets there, or
    3) Something else...

    I presume you would not RTH in this scenario, but anyway, just curious if it is smart enough and knows the relative/absolute altitude of each coordinate and figures out the altitude it needs...
     
  2. locoworks

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    my guess is it ought to rise to 20 metres altitude above point A at its current X Y coordinates and then proceed to towards point A where it should descend 20 metres and land. but i could be wrong :?:

    try it and let us know, but be in a possition to take back control if it starts to go wrong.
     
  3. Meta4

    Meta4 Moderator
    Staff Member

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    Loco has guessed right. (RTH is important enough that pilots should know how it works rather than guessing)
    This is as it is documented in the manual and discussed in many threads here.
    DJI design engineers are smart enough to have designed this out so it works in a useful fashion.
     
  4. N017RW

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    This is documented in the manual, has been discussed and tested numerous times here.

    RTH rises 20 meters above take off level (unless reset in flight), flies directly to home location's X -Y (set at take off or as mentioned reset in flight) hovers 15 seconds and begins descent until it detects it is no longer descending, bounces a time or two then lands and turns off motors.
     
  5. rrmccabe

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    Agree

    EVERY Pilot as part of first week training should initiate RTH under controller circumstances and watch how it reacts. Do this from under 20 meters and above. Also understand the fact you can set the RTH elevation at any height (within reason) during flight.

    And that RTH can happen automatically at just a few feet away with the right/wrong conditions. Always know what is between home and the bird in the event of RTH!