GPS Loiter holding issues

Im having trouble with getting the my quadcopter in loiter to keep its position.  It seems like its loosing the signal, but my gcs says the GpsHDOP is at .8 and there are at least 10 sats.  it will hold for a few minutes then suddenly takes off in a direction without changing altitude.  I can recover it by switching back to stabilize.  Its as if it received a command to go to a waypoint. 

I have set up a few of these and haven't had any trouble, but this one is a little sketchy.  Does anyone have any ideas on how to troubleshoot this and get the system working more consistently. 

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  • Thanks Randy I appreciate it

  • Developer

    Great that you got help here.  I just wanted to point out as well that ArduPilot has setup a new support forum here:  I don't personally spend much time on DIYDrones anymore.

  • Thanks for the help, seeing the data flash log definitely is helpful. 

    I think having the compass recalibrate in flight was causing the issue.  Seeing the compass error on the log seems to fit the issue I was having.  Ill get out and do a test flight to make sure, but I don't understand the motor balance failure.  all the esc's were calibrated through the software and it seems to fly stable... could the  fact that there was a fair amount of wind cause that error?  Im using rc timer motors, and they have always worked well in the past. 

    thanks again for the help, you guys are awesome!!

  • Log File C:\Users\Jeff\AppData\Local\Temp\tmpF7B9.tmp.log
    Size (kb) 2956.353515625
    No of lines 36910
    Duration 0:02:01
    Vehicletype ArduCopter
    Firmware Version V3.3.3
    Firmware Hash acf2e10c
    Hardware Type
    Free Mem 0
    Skipped Lines 0

    Test: Autotune = NA -
    Test: Brownout = GOOD -
    Test: Compass = WARN - WARN: Large compass offset params (X:-377.31, Y:-148.44, Z:-203.76)
    WARN: Large compass offset in MAG data (X:-377.00, Y:-148.00, Z:-203.00)
    mag_field interference within limits (17.00%)

    Test: Dupe Log Data = GOOD -
    Test: Empty = GOOD -
    Test: Event/Failsafe = GOOD -
    Test: GPS = GOOD -
    Test: IMU Mismatch = GOOD - (Mismatch: 0.33, WARN: 0.75, FAIL: 1.50)
    Test: Motor Balance = FAIL - Motor channel averages = [1634, 1553, 1470, 1496]
    Average motor output = 1538
    Difference between min and max motor averages = 164
    Test: Parameters = GOOD -
    Test: PM = NA -
    Test: Pitch/Roll = NA -
    Test: Thrust = NA -
    Test: VCC = GOOD -

  • I think this is what your looking for.  I wasn't sure how to create the bin file. 

    also I just noticed that the EKF_mag_Cal was set to 0 and I think for copters it is supposed to be at 2. 

    thanks again for the help


  • thanks mike, ill get them up shortly.

  • The first step would be to post a data flash log so we could see what was going on.

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