Why the drone Crashed ?

I started flying my quad copter with a pix falcon.

When i tried to takeoff, it suddenly started gaining height and went up 1 km and then fell down.

Can anyone help me in identifying the cause for the crash ?

I have attached the data flash log from the pix falcon.

34.rar

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  • Thanks Javier, Andre and Graham .

    Ill try to reduce the vibrations.

  • Moderator

    Yes, most likely vibrations, switching to stabilize would have stopped the climb. Note the 7.37! : "Test: IMU Mismatch = FAIL - Check vibration or accelerometer calibration. (Mismatch: 7.37, WARN: 0.75, FAIL: 1.50)"

    There are lots of reports of this with Arducopter, I had the same problem a couple times and there isn't any safeguard in the code to prevent this (I queried at the time and suggested that something be done to prevent it from happening) but the cure currently is to make sure your 'copter has almost no vibrations. There are firmware safeguards for GPS glitches but not for vibration-induced uncontrolled climbs. 

  • No, there is no calibration error that can produce such measurements.
  • Is it possible that i calibrated the accelerometer wrongly ?
    can that lead to some thing like this ?

  • that's just crazy and dangerous , learn to switch to stabilize when things go bad (due to insane vibrations)

  • Did you configure all your mandatory hardware as mentioned in the documentation? The throttle values sent by your radio seem really weird, unless that was you turning on and off the remote several times.

    3702383348?profile=original

    Other issue could be that your barometer may be reading wrong values. See this.

    Finally, to avoid this kind of issues all of a sudden, I always try to go one flight mode at a time. First, I fly a little bit in Stabilize mode and check for vibrations and velocity errors. Then, I change the mode to Alt. Hold and check that the copter indeed holds its altitude. Finally, I turn to Loiter. If Alt. Hold is not working properly, Loiter won't either. Also, in Alt. Hold and Loiter your throttle stick should be centered.

    Hope it helps.


    Venkatakrishnan said:

    I was planning to fly in loiter
    I tried to take off

    Then immediately the quad gained height and went out of control
    I tried switching off the remote to trigger remote failsafe

    Nothing seemed to work
    Mandatory Hardware Configuration — Copter documentation
  • I was planning to fly in loiter
    I tried to take off

    Then immediately the quad gained height and went out of control
    I tried switching off the remote to trigger remote failsafe

    Nothing seemed to work

  • It's somewhat difficult to say what exactly happened without more information. The graph is cluttered with radio failsafes and so it changes modes from Loiter to land to RTL and it's not that clear what were you trying to do. Can you detail which type of mission, including flight modes, were you testing?


    Venkatakrishnan said:

    Thank you for the reply Javier.

    You mean to say that the vibration was the cause for my drone to gain altitude and then crash ?

    no issues with mag ?

    cause it went as high as 1.25 km up in the sky

  • Thank you for the reply Javier.

    You mean to say that the vibration was the cause for my drone to gain altitude and then crash ?

    no issues with mag ?

    cause it went as high as 1.25 km up in the sky

  • Hi,

    By using the Auto Analysis tool from Mission Planner, I got the following results:

    Size (kb) 26471.8544921875
    No of lines 352152
    Duration 0:24:47
    Vehicletype ArduCopter
    Firmware Version V3.2.1
    Firmware Hash 36b405fb
    Hardware Type 
    Free Mem 0
    Skipped Lines 0
    Test: Autotune = NA - 
    Test: Brownout = FAIL - Truncated Log? Ends while armed at altitude 7.01m
    Test: Compass = FAIL - Large change in mag_field (201.63%)
    Max mag field length (701.45) > recommended (550.00)

    Test: Dupe Log Data = GOOD - 
    Test: Empty = GOOD - 
    Test: Event/Failsafe = FAIL - ERRs found: FS_BATT FS_THR 
    Test: GPS = GOOD - 
    Test: IMU Mismatch = FAIL - Check vibration or accelerometer calibration. (Mismatch: 7.37, WARN: 0.75, FAIL: 1.50)
    Test: Motor Balance = GOOD - Motor channel averages = [1597, 1574, 1547, 1544]
    Average motor output = 1565
    Difference between min and max motor averages = 53
    Test: Parameters = GOOD - 
    Test: PM = NA - 
    Test: Pitch/Roll = NA - 
    Test: Thrust = NA - 
    Test: VCC = WARN - VCC min/max diff 0.303v, should be <0.3v

    Moreover, it seems you had really weird accelerometer values in the Z axis. As mentioned in the results above, you may need to calibrate your accelerometers or check for vibrations.

    3702383465?profile=original

    Compare it to the expected values from the Arducopter documentation, and you'll see that's not normal.

    DiagnosingWithLogs_Vibes.png

    You also have radio and battery failsafes. 

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