Pixhawk BAD ACCEL HEALTH APM 3.2 - collecting data

A few users, myself included, appear to be having issues calibrating accels and/or arming when using APM 3.2 on a Pixhawk.  I see posts here and there, but thought it may be best if those having the issue could all 'check in' to one post so that the developers can see how widespread the issue is and gather data.

My Pixhawk will arm occasionally, and will even fly successfully.  Occasionally however it will not arm and I will receive the pre-arm error "Accels not healthy".  A few days ago I was able to arm and fly thorugh one lipo, then after landing and swapping batteries I could not arm due to this reason.  I have attached the logs from the successful flight, as well as the failed pre-arm logs, to this post.

As you can see from these images there is something amiss with IMU2.  This is a snippit from the good flight, showing values for AccX on IMU1 and IMU2:


and here are the same values on the second attempt, pre-arm.


In the 3.2 release thread a few users had mentioned the issue and Randy advised to set the log_bitmask to "131070" so that it will log everything including the pre-arm checks.  I encourage others having the issue to do the same and share the logs and experiences here so that we can find out what is going on here - is there a bad batch of Pixhawks in the wild that only now show the hardware errors due to something new in 3.2, or is there an issue in the APM software?



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          • Thanks Randy,

            I went and turned on logging while disarmed to get a log of the problem and I failed to replicate the problem, frustratingly.

            I have attached a log from one of my most recent flights, which seems to show IMU2 not returning any values. After this flight upon swapping batteries I got the accel not healthy warning. I have logs from earlier flights before this problem surfaced where IMU2 returns values.

            All in one linux board would be awesome! Hopefully this board can limp me through till the next gen comes out!

            EDIT: Whoops, attaching the file didnt seem to work, heres it on my dropbox https://www.dropbox.com/s/pfzcsfz9bunkeak/2015-08-28%2014-09-07.log...

            Dropbox - Error
            Dropbox is a free service that lets you bring your photos, docs, and videos anywhere and share them easily. Never email yourself a file again!
  • My hexcopter has recently had a couple of crashes recently and the only thing that I can put it down to is the control board. I am using a Pixhawk purchased from Hobbyking in January 2015. The first crash I was only about half a meter off the ground suddenly flipping, the next time I was about 5 meters high flying fine for about a moment, I then switched it to althold and it was fine for about 30 seconds then it suddenly decided to start flipping and crash into the ground. The second crash fortunately only broke the cheap legs I had on it so I flew it again with one bent prop and it flew fine.

    I know that I also need to do some PID tuning so there are already some oscillations in the readings.

    Can someone have a look at these logs and see what they think I have also had bad accelerometer health appear regularly but annoyingly on these two flights I didn't have mavlink connected at the time



    • Nothing wrong with your IMUs that I can see.

      • Any Ideas of what is causing the spontaneous crashing then?

        The only thing that I have reciently changed is I am using a new transmitter (Turnigy 9x)

  • Just found this thread, thanks so much for all the data everyone, I have been pulling my hair out trying to figure out this sporadic issue across my fleet of vehicles. I am using HKPilot32 controllers and have had this happen on several vehicles. Given I use these for work, saving a few bucks is not worth the hassle.

    I guess my question is, is there a list of known "good" controllers. So far these seem OK?




    Maybe the banggood controller?


    Any others I should be looking at to replace my currently questionable HKPilot32's? Any chance HK will warranty/replace my controllers? Have they changed or improved them?


    • I can confirm that my Bnggood controller (same as the one in your link exactly) does not have this issue, whereas an older model banggood controller does have the issue (this one: http://www.banggood.com/PIXHAWK-PX4-Flight-Controller-with-UBLOX-M8...)

      Cheers, Paul

      • Paul. So you are running latest fw 3.3.3 on this new 2.4.6 pixhawk clone, and never any pre-arm issues in cold temps, or between batteries, with IMU2, bad accel.health/inconsistent accelerometers?

    • Just short the battery connector before powering on as a work-around, and this issue will go away.

  • Hi,

     Please log monitoring and feedback.

    My second flight today, it seemed that the controller has not adhered height / mode Loiter /after the start.
    I reduced the throttle to zero and disarm motors after landing.
    The unit does not react and spontaneously adds gas. hexacopter flips and the engines are still running.
    I have to remove the battery to finished running.

    Controller Pixhawk  - firmware V3.2.1 .

    Thanks, best regards

    2015-06-26 11-12-43.log

  • I had a 'bad compass health' message on the bench with 3.2 but the issue seemed to go away and I thought no more of it. Maiden over the weekend resulted in a yet to be explained crash - wonder if there is a connection?

This reply was deleted.