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Return to home works fine despite operator error

Discussion in 'Pro/Adv Discussion' started by pureblur, Jan 13, 2016.

  1. pureblur

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    Here's the rundown of what happened...
    • Setup the phantom and did my pre-flight check in the middle of a parking lot.
    • Got the home point set notification and the green ready to fly indicator (had at least 12 satellites linked up)
    • Zoomed in on the map to verify my home point was correct before takeoff
    • Flew the phantom around until I got the fly home warning which I rejected
    • Started to fly back home manually and got to about 1000 feet from my home point (altitude of 800 feet), decided to take a few pictured before bringing the phantom in.
    • Auto return to home kicked in (no option to cancel) Distance was 1000 feet from home, altitude around 800 feet.
    • Drone might have flown a few hundred feet on it's own "returning to home" before it hovered and started to descend. (I'm not clear on if it just descended immediately or flew a little bit first, I was starting to worry and trying to figure out what was happening)
    • Drone continued to descend and was still 1000 feet from home.
    • I started worrying but hoping that it would fly to home once it descended to fly home height, which was set for 100 meters.
    • Drone kept descending past fly home height and I lost all signal as it descended under the tree line all around me.
    • I drove to where the drone had lost signal and found it sitting unharmed on the edge of land that had just been cleared for new home construction. Trees were in the spot only a month ago which you can see from the attached satellite image.
    Relieved, I retrieved the drone and started going through all my settings to see if I had somehow made a mistake. I can't see anything that indicated this could have been my fault. The home point was still set correctly when the drone landed. You can see this in the attached screenshot. My return home height was set to 100 meters like I thought. The RC Signal Lost is set to "return-to-home". Smart Go Home option is on. The battery life on the drone was at 11% when I retrieved it. The return to home option has worked in the past without a problem (older firmware)

    I'm happy that I didn't lose my drone but have no faith in the return to home feature now. I'll be extra cautious to come home early now, which shortens the length of time I can stay out.

    If I had hit a tree and lost my drone, would DJI have replaced it based on the above scenario?
     

    Attached Files:

  2. TrynFlyn

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    Sounds like you may have hit your critical low battery level, in which case it will land immediately. What is your critical battery setting at?
     
  3. Oso

    Oso

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    From what you wrote, it sounds like the P3 did all that it could to get home but you got in its way by rejecting the warning and then stopping to take photos. It sounds as if you don't yet fully understand how RTH works, especially with regards to how it will react if it is already above the set RTH altitude and how it will react with critical battery levels.

    If it hit a tree, my guess would be that DJI would say it was pilot error.
     
    #3 Oso, Jan 13, 2016
    Last edited: Jan 13, 2016
    JoBe, Richard W and SergeantJoKer like this.
  4. pureblur

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    The return to home kicked in at 30% battery life. Isn't critical much lower? I thought it had plenty of time to come back the 1000 feet.
     
  5. Wacker2611

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    You said that the battery was at 11% when you found it. How long did it take you to find it? Was it just a few minutes or were you looking for it for ages before you found it? As the previous posters have said, it does sound like you were stretching the battery - don't run it any lower that 30% and if prompted to RTH, whatever you do don't ignore it.
     
  6. G.W. Hungerford

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    If you look at your screen shot battery is pretty low and below the return to home point also below the critical I believe Tyrn Flyn may have been correct.
     
  7. msinger

    Approved Vendor

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    pureblur, if you post your flight logs, we can take a look and help you explain what happened.
     
  8. pureblur

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    Here's a screenshot I took when I got the phantom back to my car (I restarted the phantom which is why the home point changed). About 8 minutes had passed from when the phantom landed and I retrieved it/turned it off.
     

    Attached Files:

  9. msinger

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    Can you post the flight log too? It'll be hard to figure out what happened by only looking at the above photos.
     
  10. TrynFlyn

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    Low battery RTH default is 30% and Critical low battery default is 10% (also the minimum). Both of these percentage settings can be adjusted in the Go app. Do you know what yours are set at?
     
  11. Dnallov

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    If you upload your log to healthy drones, people here will be able to help decipher why your drone decided not to come back home, and in turn will help you prevent it happening again in the future. They can’t help much with the screenshots you are providing; the logs will be far more comprehensive.

    Furthermore it helps us novices understand these things better, and prevent us making the same mistakes.
     
  12. Meta4

    Meta4 Moderator
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    So your Phantom calculates how far from home and current battery level and advises return home but you ignored that and chose to delay return while you take a few extra photos.
    Then you are surprised when your Phantom descends where it is and only has 11% left in the tank and you consider that a fail on the Phantom's part?
    You're half right. It was a failure ... but not the Phantom's.
    Every now and then it pays to read the manual.
    Your Phantom was performing as it was it was programmed to and because of that, you have your Phantom intact rather than in pieces.
    There are three pages on RTH in the manual because it is so important.
    Here's a small part of it to consider.
    Perhaps reading the rest would be helpful too?
    [​IMG]
     
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  13. rfull6

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    How did you fly above 400ft?
     
  14. Rumbaar

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    You can manually set that to anything you want, up to the hardware max of 500m or something.
     
  15. Richard W

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    As they say in boating and flying ... 1/3 fuel to get there, 1/3 to get back, and 1/3 just in case (of emergency). The fact that the drone landed with 11% power capacity left dispite the pilot effort to compromise the mission validates the safety logic that DJI built into the drone.

    Live and learn ... :)
     
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  16. Meta4

    Meta4 Moderator
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    FYI .. the last 10% in the battery isn't the same as the first 10%.
    If you try to fly till it hits zero, it will fall from the air before then.
    If you want to keep your Phantom, you have to fly within its limitations rather than stretching them.
    Yours appears to have worked just fine in this situation and saved your Phantom from crashing when it ran out of power.
    The only way to have faith in RTH is to test it and experiment with it so you properly understand how it works.
     
  17. pureblur

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    Seems like the consensus is that it's my fault so I'll take the blame, hopefully others can learn from my mistake.

    My critical setting for battery life is at the default, 10%, from everything I can see, it never reached 10%. Isn't that when the aircraft is supposed to automatically land wherever it is? Not before it hits 10%? Looking at my flight log, it looks like I had about 18% battery life at the point right before I lost signal as it was auto descending. Height at that point was 118 feet.

    I've attached the flight log.
     
  18. pureblur

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    *Flight Log
     

    Attached Files:

  19. pureblur

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    My critical battery indicator went off at 28% battery life triggering the auto landing. Does it adjust from your default setting based on how far and high you are flying from the home point?
     
  20. TrynFlyn

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    Uploaded your flight log to Healthy Drones....HD is not perfect, but good enough for general info.
    It indicates a couple things. You had very poor data signal almost the entire flight. About half way thru your flight, you lost data signal for over a minute and it initiated RTH. It appears the signal returned and you continued flying. At about 15 minutes in, it indicates critical low power and initiated auto land.

    In addition, HD indicates your altitude at 1,606' and distance to home point of 1,800'+.

    Meta4 is spot on. The Phantom preformed perfectly. It appears it calculated it needed to land based on the altitude and remaining battery level. It took over 2 1/2 minutes to descend 1,500'