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Disaster GS Flight !

Discussion in 'DJI Ground Station' started by Willcoxi, Jul 3, 2014.

  1. Willcoxi

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    Recently had a near disaster GS flight resulting in a big crash although fortunately limited damage. Only second time I've used GS but everything checked out in terms of setup as per the manual etc. Set 4 basic waypoints dispersed by min 100ft all above 80ft height. Hit go and had a perfect take off then very stable transition to WP 1 then WP2. Phantom then reached WP3 and started to turn back towards me for the last leg and proceeded to take a serious fit !. Dive bombed at full speed into the ground before I could take full control back. The Phantom was only roughly 300ft away at the time an in full LOS, in the middle of the countryside i.e. no other power sources to disrupt the compass and had 8 sats in lock before take off and during flight. Now have zero confidence in using GS.

    Anyone any ideas or had experiences like this before ?

    Cheers, Ian

    Video for perusal

    https://www.youtube.com/watch?v=Z-69mcjoaSE
     
  2. OI Photography

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    This may not necessarily be related to the GS itself, it might be something completely different that just happened while you were flying a GS mission. I'm not saying it's definitely unrelated but I haven't ever heard of crashes like that being attributed to GS failures or faults.

    What version of the Phantom do you have? And were the motors still running as it was falling to the ground? LED's still on?
     
  3. Willcoxi

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    Hi,
    Yes Phantom 2 with Zemuse 3D all up to latest firmware. All motors were functioning and LED's showing nothing abnormal, as far as I could see.

    Cheers, Ian
     
  4. tbwester

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    Bizarre! Let us know if you solve it.
     
  5. Russell

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    I watched the video. Certainly everybody's worst nightmare. I have a couple of questions, if you would be so kind as to answer.

    1. What mode were you in (Phantom 2 or Naza-M)?
    2. How did you attempt to gain control again?

    I have a Phantom 2 and use the PC Ground Station software. I have always used Naza-M mode. I am in the process of testing the faithfulness of this system. I use missions I have saved to the computer and load them for flight. I have always (so far anyway) been able to stop the mission by flipping from GPS to ATTI (on the remote control) and back again. This always has stopped the mission and caused the Phantom 2 to hover. I then have full control using the remote and bring it back to me.
    Of course, this is the way it is supposed to work but what happened to you was a nightmare. So sorry for what happened. Glad you had limited damage. I hope you can find some answer to what happened. It may be that your experience will help others avoid a pitfall.
     
  6. Nidge

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    A few observations to add more confusion into the mix.

    I see in the video that you have modded the landing gear and curious as to where the compass module has been mounted?

    Have you placed any of the GS air module's antennas close to the compass module? When I say close I mean nearly touching. The reason I ask is that the GS onboard receiver is actually a transceiver and such there will be a magnetic field generated around the antennas. A radio wave is made up of an electrical component and a magnetic component and if the antennas is close to the compass module it will effect it adversely.

    Just something to investigate.

    Regards

    Nidge
     
  7. Willcoxi

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    Hi,
    Sorry so long to get back to you. To answer the questions so far:

    1. Was in Naza mode and tried switching to ATTI and back to GPS, no joy. Then tried to switch transmitter off/on, again no joy and by then too late anyway !!.
    2. Compass is mounted half way down one leg (similar position to standard although central to the platform and on the opposite side of the GS Tx/Rx, certainly no where near touching. To be honest though I don't get the interference theory as the Phantom is already carrying 2x2.4gh antennas for RC control plus a 5.8GHz antenna for FPV and GS is (should be) designed to work without interference. Also once the data file is uploaded the only info it should be Tx is positional and if that link is lost it should continue its mission autonomously ?>

    Cheers, Ian

    Ps, Unit away back to Heliguy to get checked out.
     
  8. Russell

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    Thanks Ian for the reply. That is absolutely scary. By the way, do you have the last position on switch S1 set to "Failsafe" or to "Manual". Hope all checks out well for your Phantom. Thanks again.

    Russell
     
  9. Willcoxi

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    Hi Russell,
    The last position on S1 was failsafe (although not so safe !). Am being informed by the guys at helipal that it may be due to the slight change in compass position due to the aftermarket legs I've fitted ?. So we've gone back to standard legs to see if this cures the instability.

    Ta, Ian
     
  10. NYG

    NYG

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    I have an extension kit with platform coming for my P2V+ that would lower the compass. Maybe to play it safe i'll measure the distance from the body and slide it up the leg to maintain a similar spacing. I was thinking of moving the GS module to one of the platforms for a cleaner antenna configuration. I'm also thinking of changing out the wire antennas for cloverleaf antennas. They used that black epoxy on the antenna connections though which is a pain in the ***.
     
  11. Russell

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    Thanks again for the reply. Lets hope it had everything to do with the compass because of the aftermarket legs and not anything else... But that does beg the question, did you calibrate the compass after moving it? And or, was that the first time it was flown with Ground Station after installation of the legs?
    Anyway, I hope that is all it is, and you can be flying again really soon.

    Calm winds,
    Russell
     
  12. zadok

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    Does anyone know the answer to the question, above? If one loses the 2.4 ghz signal isn't the GPS data already there? Shouldn't the heli be able to continue the mission to completion, regardless of RC, Video or GS connections? I figured that once the data was uploaded, the heli should be able to operate without any other inputs, other than the onboard systems.
     
  13. Timsytanker

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    Yes, that's how it works. If the link is lost it continues it's mission as uploaded. Had it happen to me today and watched it arrive from a 3 kilometre plus round trip.
     
  14. mattpitts74

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    Hi There Willcoxi,

    I was wondering if you have managed to get GS working again since this crash? did you fix the problems?
     
  15. stellar0645

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    I have had two similar crashes while in GS mode:

    - manual flying in Phantom mode OK
    - after flying 10 sec on the first GS leg a/c sped up and descended into the trees/ground. Not too much damage, very ruggedly built!
    - No time to cancel autonomous flight (S1)
    - home made extended landing gear of square acrylic tubing
    - compass mounted on the nearest leg and calibrated; leg is angled out, not vertical
    - other antennas on legs as per original
    - no metal on the custom landing gear
    - mylar-backed foil placed over all electronics and under the GPS, no problem flying manually
    - earlier GS flights with stock skid gear were fine.

    Is this a compass problem?
    Are there issues with replacement landing gear?

    Thanks very much, cheers . . . . .
     
  16. GearLoose

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    Initially I had serious problems using the GS, with the Phantom wandering drunkenly at waypoints, then veering off course toward a dense line of trees. I'd added extended landing gear.

    The solution was to remount the compass on the left front leg, facing inward, in a vertical position, adjusted to compensate for magnetic declination (19 degrees here). That fixed it.
     
  17. stellar0645

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    Thanks for that note. I've done the same and will report back after testing. After 2 fast fly-aways, I'll have to screw up my courage to try autonomous flight again.

    Not sure if the S1, re-gain control function worked or not, it happened too quickly. Any ideas if that still works or does the compass problem upset the S1 function?

    Cheers . . . . .