IRIS Run Amuk

Hello all,

  I am not new to APM or arducopter, but I wanted something easy so I bought an Iris+. I have flown about 10 batteries and it was flying great until this afternoon.

  I had one good flight, landed and put a new pack in and took off in Alt hold mode (since I am using the TX as it was setup). I Switched to loiter mode and the IRIS hovered fine for a minute, and then started acting unusual. It started to not respond to my inputs, so I switched to RTL and the IRIS started to climb and fly away. It was like I had very little input into what it was doing. I switched back into Alt Hold mode with no change. I managed to get it to come back to me and got all the way down to a few inches off the ground, put throttle to min, and it proceeded to accelerate sideways and slammed into the side of my house.

   This is quote unnerving and I really need to get to the bottom of it before I fly again. I am running Copter 3.2.1. I have attached my log, if anyone has any insight into what the heck was going on I would greatly appreciate it.



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  • The same thing happened to me a few weeks ago & totally knocked out the controller to the point it wasn't even bound anymore.  I had  to re-bind, calibrate everything, re-install the parameters.  The gimbal was toast, almost ruined the camera.  Before that a similar incident to what you just experienced happened.  It was coming in from RTL and a few feet off the ground decided to just smash into the hillside.  That might have been the lack of satellites near the ground?

    Here's what I think is going on...the technology is almost there, it's just not there yet.  I think 3DR is swamped w/ this stuff and the consumer has to be practically a rocket scientist to fix the things themselves.  I picked up some props at a Fry's and they said that originally they weren't going to take returns.  They've ended up having to take returns and he asked me if I thought it was pilot error and I told him "no."  I was one of those returns, my first one wouldn't even light up and that's when 3DR was answering phones.  

    The last few days I flew a site in all auto and it worked just fine (after working on it almost every weekend)  That said, every time I put it up in the air I expect it to crash and keep it away from people and property.  

    • I would never return a quad-copter to the retailer. They just sell the stuff. I too bought from Fry's but returned my Iris to 3DR after working with their tech support staff.

      No, I still haven't gotten a return / replacement.

      The point is this is a technical pursuit, and what goes up will come down... sometimes inadvertently. 

      Is the technology there?  Yes. Is the system completely mature.... no....I believe there are some problems with the Iris's design that need an expedited solution... and quick.

  • Good luck getting any help from 3DR Support.  I had some lengthy back and forth discussions with them after my drone fell out of the sky, ruined GoPro, smashed gimbal and damaged liveview transmitter.

    They offered 15% off the purchase of a new gimbal.

    I hope you have better luck.

  • Developer

    Steven you are running  3.2.1 with  AHRS_EKF_USE 0

    3.2.1 uses the DCM by default and although some of the warnings have EKF in the name they are referring to the DCM solution. i.e. it is the DCM that blows up, not the EKF
    If you graph the DCM and the EKF solution against altitude you can see that every time the vehicle accelerates to climb that the DCM YAW diverges from the EKF YAW and is about 50 degrees off at the point of impact
    Inline image 2
    Which indicates vibration induced by the high throttle.  If we graph throttle and the accel:
    Inline image 3
    we can see the correlation between throttle and the vibration in the vehicle 
    and by graphing Altitude vs Accel we can see the point of impact when the vehicle hits the ground and turns upside down
    Inline image 5
    The vibration of the vehicle adversely affects the DCM solution for Yaw.  This is a known issue.  I suspect if we look at the stick inputs at the time of the crash we will find that he is trying to steer the vehicle in one direction based on his outside observations while the autopilot is calculating a different value for the vehicle heading.
    • Well that is good to know, thanks. I am a little puzzled as nothing  on the copter has been changed, and it had been flying great. The props were all balanced, im not sure where that much vibration would have been coming from.

    • Developer

      Do you have the short legs on your Iris+?

      Change the mode to stabilize and either clamp it to a bench by the body. i.e. don't clamp the arms or legs

      and then throttle.  You should be able to see a motor or two vibrating.

  • Your compass readings are pretty screwed up (the compass interference FAIL is a clue :)). And EKF is very unhappy with this, hence the failsafe. That said this is an IRIS, so compass installed and configured by 3DR. Also the two compasses agree pretty well. Vibrations are minimal. Were you flying near anything that would affect the compasses? Powerlines for instance?

    There is also some gyro drift betwen the two IMUs right before everything goes wrong.

  • I agree with not being comfortable flying.  Is the only time you are having issues is when you put the iris+ in a mode that uses the GPS? i.e. loiter, RTL, etc?  if so then it really seems the issue is with the GPS.  Either it is bad or it is getting interference from something(maybe the antena from the receiver?), or an insufficient number of satellite connections.  I really have not seen any of these issues on the 3DR X8.  However, that one has the GPS up on a post away from the body of the X8.  I have heard that some folks have tried moving the internal antena wires away from the GPS or even modifying the iris to have the GPS on a post as well.  If you like to tinker this may be something to check out.  I know it seems like a lot of work and one would hope everything would work as is.  Hopefully 3DR will come back with something also.  

    • For me it was all modes, and I am really wishing I had changed things to that I had stabilize available to me now. It was scary to have a rouge IRIS that I couldn't even cut the throttle on...

  • I know in my case I did do the calibrations and followed the YouTube vids and the confirmation notices didn't indicate a problem with the calibrations or any of the values recorded during the calibration sequences.

    Curious to know if others did calibrations after the update to 3.2.1.
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