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Started in control...starting gyrating...lost control... returned to home... what happened?

Discussion in 'Inspire 1 Discussion' started by Wesmann, Aug 21, 2015.

  1. Wesmann

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    Calibrated at new location, Safe to fly, no nearby towers, 17 to 20 satellites... gps mode

    So we set a nice high 100meter rth height.... took off... tested controls... all was good and steady... ascended up to 150ft or so... flew large loop under control... no issues yet... lost video signal as we started from the wrong side of a house... got a better position on other side of house.. got video back... 5 bar radio and video connection now.......started to notice some speed even though all thumbs off of flight sticks.... problem stopped... thought maybe the wind kicked up or something so we proceeded with flight... we flew another 1000 feet in one direction... panned around and started to fly back towards home.... aircraft started to not respond to controller movements... it was doing circles by itself along the path of a large curve.... 25 to 35 mph ... we were able to compensate on right stick to get it in a somewhat stable position but there was not enough control to feel confident in the landing with trees surrounding... battery warning at 30% happens.... I try turning off the remote control and turning it back on .... rc reconnects but the dji app informs me that signal has been lost and aircraft is returning home... aircraft is out of view so I can't tell if the ascend to rth height was controlled or spiraling/gyrating .... aircraft comes back into view and appears to be flying nicely and not gyrating/spiraling.... aircraft lands at home point without damage..... two shaken up expensive aircraft owners feel like they dodged a huge bullet!

    So, if we post the video or the log file will that be helpful to help figure out what happened?

    Is this classified as a fly away?

    Thanks for any feedback!
     
  2. Wesmann

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    I might add that I had a totally successful two battery pack flight this morning at a different location over the water. Came home.. charged batteries... and this happened.
     
  3. sanderx

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    Can you post a video of your flight path with stick inputs? You can.use your phone to make a video and post it here. From what I am reading your quad was in TBE at one point (toilet bowl effect where the compass is fighting the gps and the flight controller gets conflicting info and can lock up as a result). Did you do a compass calibration when you took off before this flight? If so, any metal around? We're you standing on concrete e.g.? Any PowerLine were you were flying? Were your modvalues ok when you took off? We're you able to to switch to atti when it was going in circles? I'm not sure if you have but make sure that you have multiple flight modes activated in the app so you can switch to atti mode (even better, don't fly in atti mode at all, only use gps when you need to line up a shot or when you are landing). Anyway, the flight recording might definitely help.

    Sent from my SAMSUNG-SM-N910A using Tapatalk
     
  4. Wesmann

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    Thanks very much for your questions and feedback so far… The "toilet bowl effect" sounds pretty accurate in describing the flight behavior as well as how we were feeling at the time. I'll work on making the flight path video with stick inputs.

    We did the compass calibration.
    All phones and keys out of pockets.
    Aluminum chairs nearby.
    We were standing on a wooden deck. Next to a large hot tub.
    No power lines, sunny day.
    Did not check mod values... sorry, didn't know that was required.
    We did not try to switch to atti mode.

    Couple of things… The first three or four minutes of the flight had no problems with control… Any idea why the toilet bowl effect started later rather than earlier?
     
  5. sanderx

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    Make sure you check the mod values to ensure the gyro values are between -1 and +1 and co.pas values between 1400 and 1600. Close to 1500 is ideal. If they are off when you power up the inspire, move a few feet and check them again. It is hard to say why you were able to fly a few minutes before it happened. The gps and compass were probably fighting already as you mentioned that there were some glitches in the beginning of the flight. Hard to say but give the flight controller enough conflicting info and ultimately it can lock up. Word of advice, practise to fly in atti mode and try to fly this as much as possible. Your video will be smoother and you decrease the risk of gps conflict with the compass, especially is the compass has calibrated an error. I know, DJI advertises that it is safe to always fly in gps and it is if everything works perfectly togehter. However, if there is an error in the compass calibration things can go awry. Now there could be other interference in the surroundings that influenced the compass (powerlines e.g) but hard to tell from where I am sitting...

    Sent from my SAMSUNG-SM-N910A using Tapatalk
     
  6. Wesmann

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    Thanks very much for this feedback... I'll check those values tonight.

    Thanks for the advice on atti mode... I'll start doing that too.
     
  7. Alastair

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    Try the simulator using atti mode and increase the wind speed to say,
    20 mph. That way you'll get a feel for how the winds effect on your machine.
     
  8. Wesmann

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    I just checked my "mod values" ... ( hard to find under the MC settings > Sensors ) ... do these specs look right?

    Gyroscope mod is 0.00
    Acceleration mod is .99 to 1.00
    Compass mod is averaging 1450

    Do the compass and gps fight each other when it is returning to home? If they were fighting then it was able to overcome the battle.

    Thanks again for all the helpful info!
     
  9. The Editor

    The Editor Moderator
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    Classic TBE Symptoms caused by a bad compass calibration.
    Your mistake was/is because you are calibrating at each new location and you have no idea what is in the proximity that may affect the magnetometer.
    Calibrate you compass in a known good location and then leave it alone.
    As advised above, during your pre flight checklist (I assume you have one of those) always check your mod values prior to every flight.
    Additionally do NOT fly behind obstacles - 2.4ghz RF at 100mW EIRP will not penetrate buildings, trees etc and you will lose video/control signal.
    This is warned about in your manual - you should always maintain visual line of sight with your aircraft during flight.
     
  10. Wesmann

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    @ The Editor... Thanks for posting your feedback... so If I haven't re-calibrated since the incident shouldn't we see mod values out of the correct range?

    Thanks again!
     
  11. The Editor

    The Editor Moderator
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    No - your compass mod values will be influenced by where your Inspire is located at the time. If you place it on the ground and look at the value it will be different than if you pick it up and put it next to a car etc.
    You would have had a skewed compass calibration affected by something nearby you when you did the compass dance. Once you were airborne your were clear of that influence and gradually your Inspire played up.
    Have a search over the forum, this has been discussed at length.
     
  12. Wesmann

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    @ The Editor.... so if I bring the inspire back to the point of take off I should see some unacceptable values correct?

    Thanks again for those details.
     
  13. Wesmann

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    I went back to the take off site where the toilet bowl fly away happened today... I haven't re-calibrated my compass yet... the imu readings were the same as they are at my house now:

    Gyroscope mod is 0.01
    Acceleration mod is .99 to 1.00
    Compass mod is averaging 1450 to 1490

    Was this the cause of the toilet bowl?

    Thanks very much for any more suggestions!
     
  14. doubledutch

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    Good advice is to calibrate your AC at every new location.

    Its part of my pre flight checklist and will be for UK pilots with PFAW
     
  15. The Editor

    The Editor Moderator
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    Ummm... no that's actually bad advice and it has nothing to do with PFAW.

    How do you know you have a good calibration in an unfamiliar location?

    have a search on the forum and you will see that most people once they have a good magnetometer calibration leave well alone but always make sure mod values are checked prior to every flight.
     
  16. doubledutch

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    Ummm... Actually it's written into my flight reference cards, which are part of my ops manual, that goes to the CAA for approval. It's part of my pre flight check list and is quite important.
    I think I'll take the advice of the company who train you to get PFAW over an internet forum on this one. thanks though.

    edit: when flying from a new location
     
    #16 doubledutch, Aug 23, 2015
    Last edited: Aug 23, 2015
  17. turbodronepilot

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    Hey doubledutch..
    welcome to inspirepilots.com! !
    I'm using a nvidia shield and the directional pointer is greatly effected by magnetic interference. .
    when I first started flying phantoms I would calibrate my compass every battery. . (What a pain)
    Then as I transitioned to the inspire I would calibrate the first battery of the day..
    then after time I would only calibrate if I moved locations..
    after about 150 calibrations I've learned only to calibrate after a firmware update or if I travel far away..
    I must say I don't enjoy calibrating my compass and I'm very happy that It turns out it's not necessary to do so every time..
    In the past it could take several times to get things lined up and that's when it's possible to get a bad calibration ..
    there's many things that can cause interference with the compass that's why you should only calibrate where you are known to get a good calibration. .
    for me that's when my directional pointer is pointing the rite direction and my mod values are in check. ..
    one thing I do is test my rth every flight ..
    anyway ....
     
    Hercules_One and Dallasfreak like this.
  18. Wesmann

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    If my mod values were fine after calibration at the fly away location what do I make of this?

    Currently scared to put it back up into the air !

    Thanks for any advice!
     
  19. Wesmann

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    Thanks for that input.... so if I haven't re-calibrated it since the incident and I bring it to an area free of interference on the ground the mod values should be out of wack correct? Thanks again!
     
  20. turbodronepilot

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    In theory it should be,but I wouldn't spend too much time dwelling over it ..
    again..just find a good spot to calibrate your compass, get a good calibration ,and leave it alone. .
    don't move your i1 after start up without powering down first..
    make sure you did your imu calibration after the firmware update ,calibrate your sticks and go fly...
    also use a screen recoding device and a gps tracker if you're not using one already. ..