Mavic went rogue after mag interf

Discussion in 'General Discussions' started by twitchyzero, Jan 11, 2017.

  1. twitchyzero

    twitchyzero Well-Known Member

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    hello community

    Seeking for help as something went wrong with my first flight. This is my first DJI bird but I have been flying Solo for 2 years prior.

    So I've done my due dilligence before this. I did a lot of reading. Followed the safety pre-caution to a tee.

    I understand there's no ATTI mode which is what I wanted to toggle into to get familiar with manual mode.

    So i updated the firmware and went to an open field where I usually practice. GPS locked on, conditions looked good (some wind but very fair)...checked over the app and everything looked good.

    Shortly after reaching 50ft it banks a hard left...I managed to get climb to 100ft. This is when things started going further south fast.

    Mag Interf warning kicked in and I was in ATTI. Panick sets in as I noticed I had practically no control over the bird majority of the time.

    When the opportunity did arise where I was able to nurse it back above home...it regains GPS momentarily then cuts out again and fly-away kicks into high gear again.

    This went on for a solid 15 minutes until the Mavic auto-landed at 10% critical battery. Video was cached so I'm 90% confident it landed on a school's roof. Spoke with them and they may be able to get up there tomorrow morning to retrieve.

    the quick-start guide didn't mention calibration so I didn't want to mess with the default.

    Where is a good place to understand what just happened? With zero experience on ATTI I assumed control was not dead easy but where you are still able to control with confidence just with slight drifting...not something like 10% of the user input actually responded. 80% it was darting at full throttle and I had live feed and yaw was fine, but pitch and roll basically had no response. This is a field I frequent with my other quadcopters and never have I seen something behave as erratic as I have seen today.

    Thanks for reading and your inputs in advance.
     
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  2. BD0G

    BD0G Well-Known Member

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    Follow the steps in this video. It is geared to the Phantom 4 , but the process is the same for the Mavic Pro.



    Then copy the file to a location that can be accessed via a web link. Like Dropbox or Google Drive.
    Post a link to the file and members here will help you diagnose and determine where is the best place to search as well as what happened during the flight.
     
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  3. twitchyzero

    twitchyzero Well-Known Member

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    i had a look at the logs in the app

    and it looks like the entire flight's position was logged...but for some reason i got no GPS for most of it. The last position shown is corroborates the auto-landing footage shortly before it crashed. Let's hope it's there tomorrow..
     
  4. DesertWindAero

    DesertWindAero Well-Known Member

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    Valuable lesson...learn to fly in ATTI mode.
     
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  5. twitchyzero

    twitchyzero Well-Known Member

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    ^ afaik you cannot toggle atti...i've read some ghetto rigging options like tin foil but this was the maiden flight and supposed to be a close-to-launch and ease myself into it to break in the battery and to better understand its behaviour...mag interf turned it into a 2 hour goose chase with no results yet.

    On my other quad I've assigned stablized manual to a hot key...is there no option quickly toggle over in an emergency or do I have to rely on it automatically switching over? There's no delay from GPS to ATTI modes?
     
  6. 2nd2non

    2nd2non Well-Known Member

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    My experience with phantoms is ATTI mode set from switch is different from ATTI mode due to loss of GPS mode. I've always had more control when you can manually change it via switch to ATTI as the system doesn't keep going back and forth between modes causing instability. I really hate the mavic doesn't have a switch to put into ATTI, this will lead to more loss of control "fly aways".


    Sent from my iPhone using Tapatalk
     
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  7. Kilrah

    Kilrah Well-Known Member

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    How do you determine that? Were you looking at the aircraft? Because you wouldn't see pitch and roll response on the screen.
     
  8. twitchyzero

    twitchyzero Well-Known Member

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    ?

    camera pans (yawing was fine), climbing and decsending also seemed OK, right stick was basically unresponsive and it was flying faster than wind currents + momentum away from home

    i was default in Mode 2 for the sticks...GPS 15-18 sats at take-off.

    I dont understand how it was stuck in ATTI for so long...if it flew 8 blocks away it should pick up a few sats down the stretch and auto-RTH once it cleared mag interf if there was any near home.
     
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  9. 4wd

    4wd Well-Known Member

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    Being in ATTI due to loss of GPS doesn't explain wild behaviour.
    The stick response should be unaffected you'd just have to factor in wind for example fly diagonally to maintain a straight line.
    It sounds more like a compass issue to me.
     
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  10. Kilrah

    Kilrah Well-Known Member

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    Due to the gimbal doing its job and completely hiding the aircraft's pitch/roll movements many people think their aircraft is unresponsive since they don't see anything happening and give up when everything actually works fine, they jsut need to hold the control input for several seconds before it has a visible effect on the image (map/values would be quicker to vary visibly, but they don't think of looking there).
     
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  11. younumpty

    younumpty Well-Known Member

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    I take it you didn't calibrate the compass? If I'm wrong apologies I calibrate before every first flight of the day. If not the bird got confused and had no clue where it was, I wish we could fly purely manual in emergencies like the first firmware releases of the P3 before they made F mode multifunctional for other modes etc. Least we could fly home on a simple 3 axis stabilisation mode like a cheap drone!



    Sent from my iPad using Tapatalk
     
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  12. BlakPhoenix

    BlakPhoenix Well-Known Member

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    A calibration is not required daily. If you are in an area with strange magnetic interference/stressed concrete/underground
    cabling then calibrating your compass there will cause more harm than good. You should however ALWAYS check your sensor screen before EVERY flight. You can see how the IMU, compasses, etc. are behaving. It will not save you if you do fly over something terribly magnetic or disruptive but at least you know you're starting with a stable platform. If you notice discrepancies in your pre-flight check you should then consider calibrating, or changing location to avoid the interference.


    I agree that a full manual mode would be welcome, we see a lot of stories with people having interference/unresponsive issues like this when the compasses and GPS have issues. A simple ATTI with no compass/GPS input could be useful to get home when these instruments begin conflicting.
     
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  13. Tok Pilot

    Tok Pilot Well-Known Member

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    Isn't that what sport mode is for? Full manual only needing the GPS for hovering (as long as you have visual on it you can make it go wherever you want). I hope so, I've had some GPS loss issues myself, but was under the impression that I can bypass the need for compass and GPS in sport mode, if not, I'm in trouble.


    Sent from my iPad using MavicPilots
     
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  14. GetDatMoney

    GetDatMoney Active Member

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    I understand that there's a lot of seasoned pilots here but one thing for new pilots especially those launching their Mavic for the first time make sure your in beginners mode. That will at least limit the height and distance in cases as such.
     
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  15. twitchyzero

    twitchyzero Well-Known Member

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    So I retrieved the Mavic today. Havent fully assessed damage but looks like only 2 props gone. I consider myself lucky no one was hurt and no property damage.

    Regardless there's no way I can trust it again. It's going back. Or get DJI for a replacement. Any word on how long that turnaround is for, for those who've recently done it?

    this is good to know

    but i'm talking the bird was flying backwards probably a solid 7-10 m/s and right stick forward does nothing. Yaw the bird 180 degrees, punch right stick backward, STILL NOTHING. Awful feeling seeing a brand new Mavic flying away after waiting 4 months for it.

    I think this could have an even worse outcome as there are obstacles in the area that may not clear 30m. I quickly toggled it off when it started darting around on its own terms.

    Can anyone else confirm?

    Sorry, that seems like a conflicting statement? So Mag interf = move, what does a discrepancy in sensor menu look like? There will be a warning something is acting up and requires calibration?

    So all the seasoned flyers here, please tell me what's your emergency plan? Say GPS cuts out, then what? Fly ATTI? What if it keeps jumping back and forth between all the modes? What if your right stick basically become unresponsive...what's your idea on how to best bring it back/take on damage control?

    This seems like a very important dialogue to have as a community given no ATTI toggle in the Mavic...we're expecting it to auto-switch which is not fool-proof.
     
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  16. BlakPhoenix

    BlakPhoenix Well-Known Member

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    Sorry, I may have worded it confusingly, let me try to clarify.

    If you go into the menu in the Go app then tap the top menu button -> advanced -> sensors -> IMU/compass it will show you two bars each (one for each IMU/compass the Mavic has). If they mostly empty/just a little green then you're good to go. If either are yellow/red or vastly different (eg. one empty and the other yellow) then you need to calibrate/move locations.

    If you're getting bad readings then you should try to relocate and see if the sensors get better (just walking a short distance with the drone in hand should be enough), this means your original location had interference. If this doesn't help then you need to check for anything that may be causing issues in both locations. If there is nothing that should be causing issues, you can perform a calibration. Be aware that lots of man made materials have magnetic properties, so best to calibrate away from any structures, etc.

    If the drone is being unresponsive to stick commands your best bet is to first try a RTH command. This removes RC commands from the equation and just lets the drone work on its internal instruments. If this still doesn't help, then it's probably the drone having issues internally and I'd try kicking it into Sport mode. That should hopefully tell it to stop listening to it's sensors and let you override using the RC. If neither of those help then try to follow it/change the vector your signal is taking, as you may be able to get through the noise/interference from a different position.
     
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  17. younumpty

    younumpty Well-Known Member

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    I still say we should have a no frills mode to manually fly. Sports is governed by GPS and if you're getting trouble from conflicting sensors you've no way off bypassing them to free fly. I agree with checking for interference. It goes without saying I have my safe spots for doing solid trustworthy calibrations before I fly. I just do it from habit as the one time I didn't my P3 went upside down at 80mph into a mountain side!


    Fly safe... :)
     
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  18. Tok Pilot

    Tok Pilot Well-Known Member

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    I assumed that the only thing sport mode is using GPS for is to maintain heading and position over the ground when you turn loose of the controls and stops and hovers. It doesn't need GPS to go in the direction you tell it to go, am I wrong?


    Sent from my iPad using MavicPilots
     
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  19. younumpty

    younumpty Well-Known Member

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    To my knowledge gps is on so it's stable and stops dead when you let go of the sticks. When you hit return to home it still works so if it's confused it will still fly the wrong way. Sadly there is no true free fly mode.


    Fly safe... :)
     
  20. Tok Pilot

    Tok Pilot Well-Known Member

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    But only if you hit RTH should it need GPS, so if you have visual on it and need to bring it home in sport mode you shouldn't need GPS right? Should be like free mode?


    Sent from my iPhone using MavicPilots
     
    #20 Tok Pilot, Jan 13, 2017
    Last edited: Jan 13, 2017
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