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Out of control - non-human-error-crash.

Discussion in 'General Discussion' started by Darrell1, Sep 5, 2013.

  1. Darrell1

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    100's of flights. Zero crashes, now I had a major crash - NOT human error!

    This sounds like the same story as fly-aways, except mine "flew away" into the ground.

    About a week ago, I upgraded the board, made sure it has the latest firmware, and have had about 16 successful flights with the upgrade.

    Then over the weekend, I had one successful flight, brought it back and changed batteries for flight number two. I waited for warmup, GPS lock, and took off in GPS mode. I flew about 30 feet high and 50 feet away. When it hovered, it drifted quite a bit which surprised me. Then, the green GPS light gave me one yellow flash. I knew something had to be wrong. It then gave green flashes again, but because something had to be wrong, I decided to bring it back home. 5 seconds later, it wobbled bad, tipped on its side and dove hard onto a wooden deck.

    Smashed GoPro lens, ripped gimbal off, cracked the shell. Everything inside seems fine, except, it's like the GPS module is not plugged in MOST OF THE TIME. When I power cycle the Phantom, about 10% of the time it knows the GPS exists, sometimes it does not. When it does, sometimes it only sees it for a few seconds, sometimes for a few minutes. It's just intermittent.

    I've ordered a replacement board, thinking that is the problem, but I'm not sure. It appears to either be that, or the GPS.
     
  2. bumper

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    Darrell,

    Where you flying in an area where there could have been other 2.4 ghz interference? Are you using the stock controller? The RF control signals are not all that strong, and the stock receiver, such as it is, does not seem to be all that resistant to spurious RF interference.

    Sorry about your experience.

    bumper
     
  3. Darrell1

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    Yes, I was at a campground which has a strong Wi-Fi signal. But,

    1) I have flown there before
    2) Wouldn't interference cause it to fly away instead of becoming unstable?
    3) Why the one yellow flash and why now, does it only sometimes recognize the GPS is attached?

    The only conclusion I can come to is a component on the board (or the GPS itself) failed.
     
  4. DeweyAXD

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    The Yellow flash makes me think an interference issue too. Try turning your Phantom on before switching the TX on and you will get yellow flashes.

    I think interference is something that people think is either there or is not there but that is not the case. You can fly around a 2.4gh Router all day long and never have a blip of an issue. It totally depends on what data is being sent and how the RX translates it. Most of the time it sees the 2.4 and says "Ok that is clearly not a command meant for me" and ignores that data (backed up by the signal from the TX being much stronger). Then that day comes when something gets transmitted that actually sounds like a TX command... this confuses the RX. Sometimes that can cause a minor effect but sometimes it can lock onto it and decide that this new transmission is the TX talking to it.... even if the signal says to do something stupid.

    I am no trained radio expert but I deal with wifi signal interference in I.T. regularly for customers and the same applies. Two routers on the same channel can work fine a lot of the time (your neighbour having the same as you for example)... but some days they will conflict causing internet drop outs. In that case you can change the channel... in the Phantom case you crash or fly away.

    All that said it could be something different... try your motors on the ground and check to see if any are hotter than the others, check the C clips to be sure one hasn't come off, check the Naza assistant and make sure your Attitude mode flip switch mix isn't accidentally flipping between Ati/Manual mode (unlikely but 3.16 resets stuff).
     
  5. Loppy

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    1) that's well and good, but not a guarantee that rx interfearance wont bounce in at random
    2) not at all. depending on the infringing signal signature, movement can be fully 360* 3 dimentional.
    3) could the yellow flash been a compass issue? Whatever caused tx/rx interfearance could also have messed with your compass/gps.

    I'm with Bumper. Have you phsically seen a stock phantom RX and the guts of the TX? Trusting $1000 worth of quad to that junk is a joke.
     
  6. Loppy

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    This guy said it better. :mrgreen:
     
  7. MrMediaGuy

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    +1 on the stock TX/RX. I mean, honestly, I think they do pretty well for a $650 unit -- between the NAZA and motors and ESCs and whatnot, there's pretty decent value packed in there, so we can't really expect top-of-the-line Futaba quality. :) And as was noted, the signal strength is pretty low in the first place; PPM links don't need a ton of power to get good range out to the fringe of LOS, which is all Phantom is designed for. (Think about how long your TX batteries last and ask yourself how many milliwatts it could really be putting out...) :)

    I would check both the GPS connection to the main board, however, as well as your compass connection internally and externally, as well as the GPS wiring inside the roof (peel off the foam and have a look). You may also have a cracked ceramic antenna element on the GPS at this point since your crash sounds pretty dramatic. If the ceramic is cracked the GPS will perform sometimes and not other times, or won't get a good lock anymore. The replacement is about $160 but I read on another board about someone who replaced only the ceramic element for about $15. Simple soldering job.
     
  8. ArshadR

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    This leads me to believe that the yellow flash and potential RF interference may be a red-herring.

    Regardless of interference, unless it's in manual mode, it should never tip on its side and smash into the ground. Mine did this on its maiden flight (except it completely inverted) and turned out to be an ESC failure which caused one of the motors to stop.

    I wonder if something similar happened here? Are all of the motors spinning up fine?
     
  9. DeweyAXD

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    I think that is perfectly plausible ArshadR... who knows what happens to the LED when an ESC gives up afterall. As always with these things it could be sooo many reasons. At least the ESC's are easy to test in a new shell.

    That said interference on the Ati switch channel would make perfect sense for the reasons you describe (going to manual mode)... basically sending a signal out to the RX to say "go to Atti mode" (quick yellow light) then "go to Manual mode"... kinda like flicking the switch down yourself. That theory would be disproved if you have failsafe mode programmed on the 3rd pole of your switch rather than manual mode. If its set to FS then that couldn't happen as the signal would just tell the Naza to go to FS mode not manual.
     
  10. ArshadR

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    True enough. In my case, I did not have manual mode set up. Presumably there is no way for the FW to go into manual mode on its own without it being setup from the SW.

    So Darrell: Have you enabled manual mode on your phantom?
     
  11. Driffill

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    When you installed the upgrade board, did you restick the foam over the GPS? I could be looking towards the wrong thing here, but perhaps the naza is causing interferance with the GPS module?

    My reasoning? . . . The "yellow flash" could be the naza indicating that it has switched to ATTI mode due to bad GPS data. I still firmly believe the compass is still used in ATTI mode, and because the compass data runs via the GPS module, anything that can corrupt the data coming from the module could also affect the compass data. If that's the case, both GPS and ATTI modes could be unstable.

    On the other hand, if option 3 on the GPS/ATTI switch is set to manual, a rouge signal from wifi/microwave could hit that channel and enable manual mode. tho its quite unlikely, and more probably enable a FS mode (even with manual mode selected for option 3, if the naza receives a signal that sits in between the GPS ATTI or manual positions, it will assume the tx has malfunctioned and trigger fail safe!)
     
  12. Darrell1

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    I did not have manual mode as an option, so even with interference, it should not cause it to flip.

    When I replaced the board, I did not need to remove the GPS, so that shielding should be fine.

    Now, today, most of the time it does not realize the GPS module is connected. Without touching anything - just power cycling, about 10% of the time it will see it. When it does, sometimes it only sees it for a few seconds, sometimes a few minutes.
     
  13. Olek

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    I just had a crash that seems similar, although I lost both Phantom and GoPRO 3 hero black in the Detroit River.
    I had been flying it only for a few days now but felt confident in controlling it.
    It was updated, GPS was on and IOC set to manual, I waited until there was only green light flashing before take off.

    I only took off went over the water turned around and started moving back. Maybe 30 seconds total. There was a gust of wind that made the Phantom lean into it quite a bit. Then it turned completely on its side and dropped like a stone in the water from about 15-20 meters, never to be seen again.
    Heart broken. That's it.

    1. Could wind make it fall to the ground?
    2. Could it be because the GPS mode made it lean too much against the gust of wind?
    3. Could interference make it drop just like that?
    4. What other reasons could have caused it?

    I don't have the phantom to investigate so it can only be speculated.
     
  14. martcerv

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    Regarding compass in ATTI mode regular NAZA multi's fly just the same in atti mode with or without a gps unit. These gps units do have the compass built in so a NAZA without GPS doesnt have a compass but still has atti mode.