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Why is the drone home point when RTH never accurate

Discussion in 'Pro/Adv Discussion' started by adjmirealty, Jul 14, 2015.

  1. adjmirealty

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    Every time I return to home the P3 will decide to land 10-30 ft away from me... Sometime I fly it on my balcony and would love for it to land on the balcony not on the house I hate having to cut out RTH and take over... My other question is can you cut out RTH when the Battery Low RTH mode is engaged because if I can't this things landing on my house... Thanks guys
     
  2. ScottyT

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    Mine seems a bit more accurate than that. I might get 3 to 10 feet max - although I will never allow RTH to land it if possible.

    You can cancel RTH by using the app or pushing the RTH button again.
     
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  3. adjmirealty

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    That's true maybe it's around that range...but still why isn't it dead on... Longitude, and Latitude is very a very accurate system I'm guessing it's tracking those coordinates when recording your home point
     
  4. Mako79

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    You don't want it to be too accurate. If you set up dynamic home point (DHP), your smartphone/device becomes the new landing zone. You better know how to cancel RTH otherwise you maybe typing with a straw...

    DJI has set so it starts descending when its within 20m/65feet from the home point.
     
    #4 Mako79, Jul 14, 2015
    Last edited: Jul 14, 2015
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  5. Dave Ward

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    If you request the RTH within a 65ft radius of the home point, it will land wherever it's currently at (which is pretty dumb, honestly). This confused me at first too, but it's apparently by design. From the manual (pg 14):

     
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  6. dedstik

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    Wow...when I have used the RTH command my P3 lands within 24" of my take-off point.

    I always do a compass calibration before every flying session, maybe that contributes to the accuracy of my RTH landings.

    :harry
     
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  7. ScottyT

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    I think GPS accuracy is better than 30 feet and 10 feet for very good receivers. You'll never get an exact landing each time.

    I'm not sure exactly why, but it kinda makes sense. If it was less than 20 meters away, I'd generally be in full control with vlos and just want it to land....not ascend to 60 meters, fly a couple of meters, then descend and land.
     
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  8. Mako79

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    I think DJI has designed an underlying "failsafe-failsafe-RTH" system in the P3. I haven't had the chance to prove this (cold in Aus to fly).
    What used to happen in previous models was when RTH was triggered, it would fly straight up to the nominated RTH height (usually 20m).
    This scared a lot of pilots when they unintentionally activated RTH. Eg trying discharge battery with props on or accidently turning off the controller whilst the props were running or knocking the controller and the 4xAA batteries fell out etc...

    Its common sense if you think about it... if the phantom is a few meters away, why would you need to activate RTH when you can simply land it your self or hit the auto land.

    I might start a thread on it as I cannot find it in the "extensive DJI" manual.
     
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  9. ScottyT

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    I hear ya. I live in Melbourne and it's fricken freezing...that and the fact I live in the CBD. I've not flown in over a week...

    Agree. I guess it basically turns in to a physical landing button when it gets close.
     
  10. adjmirealty

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    I'm not sure exactly why, but it kinda makes sense. If it was less than 20 meters away, I'd generally be in full control with vlos and just want it to land....not ascend to 60 meters, fly a couple of meters, then descend and land.[/QUOTE]

    Was just thinking the same thing when I was trying to figure that out... And that's pretty true.. But basically what they didn't teach us is that if your on top or near an object do not hit RTH while 20m in range for it will land or crash into the object... And also that's 20m plus the 3-24" inaccuracy of the home point
     
  11. adjmirealty

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    ^^^^^^^^^^^^^^^^^^^^^^^^

     
  12. Dave Ward

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    I had a couple near misses with obstacles within a 65ft radius of the home point when I first got my P3 and tried the RTH feature within that radius (not understanding that RTH doesn't actually mean RTH).

    Within that 65ft radius from my back deck, there are a plethora of trees, a couple neighbors' property, and a handful of fences. RTH is essentially a minefield for me unless I know I'm definitely 100+ feet away from the home point. Do not like.
     
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  13. adjmirealty

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    How do you hit the auto land? This only works 20m in range...I thought RTH was only way to auto land... Also do you know in settings what RC signal lost.. Return-to-home or Landing what the difference is I've been curious
     
  14. SitkaGrover

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    He was commenting on the fact that if you are within a certain distance, hitting RTH will just cause your quad to land versus flying to a spot and landing.

    If you have RTH selected and lose your TX signal, your quad will RTH.
    If you have LAND selected and lose your TX signal, your quad will LAND
     
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  15. ScottyT

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    Yeah, it's illustrated in the manual, but agree it should probably be emphasized somewhere - perhaps a "README FIRST!" one pager stuck on the top of new phantoms with that, CSC mid-flight warnings, RTFM etc

    There is possibly inaccuracy in that distance too, I'm not sure. Would have to try it and see
     
  16. IflyinWY

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    My guess is that you haven't allowed sufficient time for the NAZA module to accurately record your home point. Do you give it sufficient time to record the home point?

    Here's a quote from something which is not specifically for your aircraft but I think it's the same NAZA module:
    "Home-point: Before takeoff, current position of multi-rotor will be saved as home-point by MC automatically when you start the motors for the first time after 6 or more GPS satellites are found (red light blinks once or no blinking) for 10 seconds."
    From this:
    http://download.dji-innovations.com/downloads/nazam-v2/en/NAZA-M-V2_Quick_Start_Guide_en.pdf

    So, if you are not allowing enough time for the data to compute, like you get a go and liftoff right away, perhaps that's the cause.

    You could test this by taking off as you normally do and heading out in one direction, then testing RTH to see if that's where it goes. To confirm, you could do the same but head out in a different direction and see if it thinks Home Point is out there.

    Welcome to the party adjmirealty, hope you enjoy the show. :D
    There are some helpful links in my signature.


    Oh yea, add on a quadpad on your roof. :eek:
     
  17. IflyinWY

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    I'm not sure if I'm reading this correctly, but it's sounding like some folks say it should land "somewhere around" where it took off from. :eek:

    Nope, it should land within a couple feet of where the "Home Point" is, and that's on a bad day. :)

    On a good day, it should be within inches, not feet.
     
  18. adjmirealty

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    Got it very well understood... And Very well said
     
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  19. ScottyT

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    Mate, with all due respect, I think you might be in the wrong forum, and drunk. Naza this, MC that.
    I think the Phantom 3 might behave differently from what you are used to :)
     
  20. IflyinWY

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    You're probably right. I guess the P3 doesn't have a NAZA module controlling it.

    And that's the reply I expected.
     
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