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What i dont understand about fly aways with RTH

Discussion in 'Phantom 2 Vision + Discussion' started by borgqueenx, May 8, 2014.

  1. borgqueenx

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    If the user set the home location before flight, i dont get how a fly away can still happen unless DJI lied or gave us a super buggy failsave.
    I remember i have seen a video about a dji guy explaining if it receives exactly desame command 10 sec straight it stops, then 10 sec more it continues. If it then still receives exactly desame command it triggers failsave mode and returns home.
    So a phantom can't keep on flying away without nothing happening unless the homepoint is not set?
     
  2. garrock

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    The Phantom saves the home location once the rotors fire up (I assume).
    If the GPS is not locked on by then, the saved home location can be in error.

    Like a cell phone when you bring up maps; sometimes the location is off until it gets a better lock.

    DBS has a video explaining this but I can't find it.
     
  3. lilwheat

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  4. Mori55

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    Has nothing to do with rotors. When it gets sat lock it'll blink green real fast then blink green slow. Now you have your home point.
    Really need to read manual.
     
  5. doug86

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    IF....

    (or worse, perhaps there is a glitch somewhere, and even IF the home location is properly recorded at the beginning, but something interferes with the GPS signal, could that something also scramble or otherwise change the home location to somewhere else? That could mean that the home point is re-programed during what started out as a proper flight.)
     
  6. garrock

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    Wierd.. twice I have powered up my machine and let it do its light sequence. Then I moved it about 20 feet or more for take off. Then did an RTH. It landed a few feet from take off.
     
  7. rostov007

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    This is why I have never agreed with posters on here firing back at a question with "really should read the manual." He's right that the manual explains the light sequence and what they mean. But I have also experienced the exact thing you are talking about. When I launched I had the fast green lights, but my bird was drifting instead of hovering in place when I released the sticks. I set it down, left stick down to turn off the props, started up again, and took off this time to a beautiful stable hover. To check it I set down again and repeated about 20 feet away, same result.

    At worst I think we are all just not waiting long enough to fly. It takes longer to get a good fix than we think it will and perfect compass calibration every time is my mantra.
     
  8. Aqeel200

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    an add-on good logical explanation. The software codes can consider these factors as being logical and illogical state. The same can be done to address if the GPS location/signal was interfered and be set elsewhere..not only that the software codes could trap the sudden change and inteferences(signalling measurements/QOS sudden/abnormal/illogical changes), it is also illogical that the home location can change while in flight within a logical time frame..ie. considering someone is driving and passenger is piloting the phantom in a moving car, or on a moving boat - all this can be built into the codes. DJI rely on its phantom to be intelligent and in the cases of flyaway(wrong home location), it is not intelligent enough, maybe.. Being stationary is quite straight forward logic.

    just my 2cents opinion.
     
  9. JimDE

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    I will add this... how many times while driving and using a GPS mapper have you seen everything go askew and you are no where near where it say's you are and even the compass heading are off? Imagine this happening to your phantom while in flight......

    I have said this many times.. this is a very high end technology that imo as of right now with these quads is truly not ready for primetime in the area of reliability.
     
  10. Didjelirium

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    I'm not sure how much your phantom is drifting, but it seems to me that some of us might have too much expectations about the hovering stability of that bird. What i mean is mine always drift slightly at first, then moves back in place, then drift a bit more in the opposite direction, then corrects its course again, in circles smaller and smaller until it starts hovering pretty much in place, though the wind obviously affects its position.

    Bottomline : if you expect your phantom to simply hover as if magically suspended in the air, this is not gonna happen. It does drift a bit at first then will correct its position. Do you leave enough time for it to correct this or do you automatically try to guide it back in place ? I know it took me a few times to trust it enough to let it do its thing, and i have more than 15 flights so far with no problem whatsoever, phantom and nazam modes, even between buildings and in tricky situation. So far, amazed with the stability of this bird.
    Though I'm conscious problems may occur anytim

    I always give it time to do whatever it has to do, don't be too quick in flying away, try the home lock thru IOC to double check the home position. I systematically do the same tests before each flight.... So far lucky enough to be major problem free.

    Be strong, it IS possible to enjoy flying with these products.

    Bless !
     
  11. syotr

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    The Phantom has a computer which is connected to many sensors (barometer, GPS, acceleromters, compass.) If any of these sensors fails and sends the wrong information to the flight computer, It will try to correct something that is not wrong. The computer has no way of knowing that the input data is wrong. Another possiblity is some grit or an insect in the motor. This would slow one motor down and the computer cannot speed it up to correct the problem.
    Overheating of a motor or speed controller could cause a similar problem. There are many things which could cause a flyaway which do not involve bad radio signal, interference or GPS errors.
     
  12. Madwak

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    If your phantom starts to fly away try doing a CSC to stop the motors, if it works then it WILL crash but at least you will have something to repair instead of just fond memories. :)
     
  13. Aqeel200

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    while driving, at times it is a ittle bit off("turn right at junction 50 meters" , but i suddenly past the junction)..mainly due to lag..but so far I have never been off by a few miles tho. my family use waze and google when driving in unfamiliar places.

    Once Waze home location was not configured correctly, yes, i was off by about 300 miles from where I am..but its a home location configuration that was wrongly setup.
     
  14. davephantom

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    I fly in forrested areas where GPS lock is not possible, I fly atti and don't worry about it, if it flies away it will be a hardware failure and I can't control it. I hope it doesn't happen but the option for GPS lock completely limits the areas you can fly. When flying when I break above tree canopy or canyon walls often will get GPS lock at that point as it has enough satellites. I wish there was an option to disable GPS completly in atti mode, save some battery and potential hassles or failure.

    It is annoying this is only an option in manual which is not possible to fly and take pictures at the same time (you really need to focus on controlling the aircraft every millisecond especially in wind).

    I have been thinking about wiring a switch so I can enable / disable GPS physically. I wonder if it would still fly / work in Atti without GPS completely.
     
  15. borgqueenx

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    You guys talk about GPS like its so prone to error.
    Yet on all the GPS devices i had, it knows when the lock on location is good and keeps it.
    i never ever had my gps say im in a location where i am not.
    Ofcource it starts with a big area(probaly cell tower location) then quickly moves closer, then gets a 100% lock thats like 5 meters accurate.
     
  16. Aqeel200

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    Maybe dji did not use a carrier grade gps hardware in their phantom. Carrier grade gps in our mobile phone is quite accurate I believe. We never had to calibrate and do the apache dance wt our phone to get a lock on a location. The calibration dance is somewhat funny the first time I saw it on utube but I still buy the phantom.. Just a thought.
     
  17. AnselA

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    The "calibration dance" is not used to calibrate GPS...
     
  18. MikesTooLz

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    the calibration is done for the compass, and yes you have to calibrate compass's on phones as well and the ones on phones dont seem to be as accurate as the phantom.
     
  19. Aqeel200

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    oh really. we have to calibrate it as well. i never had to do it on my S4. maybe it was already done by the factory once. tested a Global Tracker TK-102 and compare it with my S4..the later test shows almost identical results when i am in the house(S4) and global tracker TK-104 outside of the house. viewtopic.php?f=27&t=14420&start=70

    As a newbie, I still cannot relate the compas with the GPS and why we have to do the calibration dance regularly (comparatively to something like using googlemap or Waze while driving to find directions to a specific location, anytime from any location)..especially if you change your flying location to a different park..at least that was my conclusion.

    Nonetheless, I follow suit when I fly my P2V+
     
  20. panhygrous pantler

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    You don't have to have to recalibrate frequently.

    I've calibrated three times in the last year. That's over two Phantoms and flying locations hundreds of miles apart.

    Calibrating frequently give some folks a feeling of comfort. Just like the folks who incessantly push the elevator button. They feel better but they aren't accomplishing anything.