Pixhawk BAD ACCEL HEALTH APM 3.2 - collecting data - Discussions

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?

goodlog.bin

badlog.bin

Replies

Zeke Zero January 13, 2015 at 12:10pm

I've carried out some tests and the very limited results would suggest this phenomona is temperature related.

Leaving my quad in the boot of the car overnight resulted in a pre-arm fail on the last two mornings. The temp was 2 degrees and 5 degrees (celsius) (as shown by my car temp gauge). I tried to arm 3 times in a row each morning and each time the pre-arm check failed.

I brought the quad into the house and left it next to a radiator for an hour, retested and the pre-arm checks passed (first time on each morning after being warmed up).

I will continue testing until Friday and post results.

Zeke,

UK
- Pascal Turcotte > Zeke Zero January 13, 2015 at 12:20pm
  
  Yeah maybe temperature related as well...
  
  Was cold the day I had in mind to do the first flight, like -15oC (5oF)
  
  Had issue with the ACC, tried to calibrate the ACC outside without any relevant result.
  
  But S900 has been on my table for a week at same temperature and it has refused to arm because ACC / Horizon was not straight. So... not too sure it is temperature related...
  
  pturcotte
  
  Canada
  - Artem > Pascal Turcotte January 13, 2015 at 12:24pm
    
    try disconnecting your backup BEC and see how it goes. In my case almost 2 weeks with no acc issue even when I was in the mountains about -10 Celsius...
    
    p.s. my acc problems started when I connected a BEC for landing gear, after I moved BEC to Rx and disconnected power wire from the sbus plug I have no issues... almost 2 weeks now.
    - Pascal Turcotte > Artem January 13, 2015 at 12:30pm
      
      I only have the CC BEC PRO nothing else... The power module is not strong enough (45 amps).
      
      And I have other modules as well
      
      Spektrum TM1000
      
      Spektrum Current module
      
      Spektrum GPS module
      
      AR9020 + 2 sats
      
      915MHz Telemetry
      
      Regards,
      
      pturcotte
      - Artem > Pascal Turcotte January 13, 2015 at 12:33pm
        
        what is the voltage of your castle BEC?
        
        Pascal Turcotte > Artem January 13, 2015 at 12:37pm
        
        default I think it was 5.1V when I measured it...
        
        We would need to check and compare it with the power module.
        
        INRUSH, Startup, overshoot, undershoot, etc.
        
        Regards,
        
        pturcotte
        
        Fred Goeddert > Pascal Turcotte January 14, 2015 at 5:42pm
        
        Just to let everybody know how this issue effects my trad.Heli with the 3DR PIXHAWK Autopilot. Installed: APM-FW 3.2
        
        For the motor I use 12 S ( 2X6S LIPO)
        
        For the HV Servos = one 2S Lipo
        
        For the Pixhawk , the 3DR Power Module = one 3S Lipo
        
        The 12S get's monitored by my TX Telemetry.
        
        I have the pre-arm error 'Accel not healthy' only and each time when I connect the 3S LIPO first (3DR PM for the PIXHAWK) before the 12S (50.4 V).
        
        If I connect the 12S first with a bit of a spark everything is fine. Even if I connect the 2S Lipo for the Servos after the PIXHAWK the pre-arm error does not appears.
        
        Fred.
        
        Fred Goeddert > Fred Goeddert January 18, 2015 at 12:31pm
        
        The 3S Battery is not the problem!
        
        I believe that the 12 S connection for the motor with a spark is effecting the senors when the Pixhawk is already connected before the motor.
        
        Fred
        
        Earl > Fred Goeddert January 17, 2015 at 10:09pm
        
        I Get Bad Lidar Health ... but it works.
Vic 33 January 6, 2015 at 2:46pm

Hello!

I'm coming back for the bug of the day

Naturally my drone never cross the runway ;-)

it stayed put down on a table on the aeromodel track, this is a screen-shot of my DroidPlanner Tlog.

Note that the GPS had a 3D fix, but Prearm altitude disparity alarm, and the HUD look very much like a Redbull air race!

On the DF log IMU2 is in a mess, it's the first time for the V3.3 :-(

T° about 12°C, 4 reboot in order to have everything good, and 1 flight, poshold, rtl, guided, follow, land.

joint: bad Tlog and DF log

cheers

2015-01-06 16-18-34.bin

2015-01-06 16-16-10.tlog

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