Crash Analysis Help - EKF Failures, Compass Inconsistent, GPS Dropouts (ArduCopter 4.5.7)

ArduCopter
1

I recently experienced a crash during an autonomous mission and would appreciate your help in analyzing the log to determine the root cause.

Log file: https://drive.google.com/file/d/1xIwDo11VYJ04t_DFK39nqGQZwaGS4jkh/view?usp=sharing

Drone details:

  • ArduCopter version: 4.5.7
  • Flight controller: [ Cube Orange ]
  • GPS module: [ Here3]
  • ESC: [ALPHA 60A 12S]
  • Flight mode at time of crash: [GUIDED]

What I observed:

  • The drone lost altitude rapidly near the end of the flight.
  • I noticed EKF errors in the log: “EKF_PRIMARY changed”, “EKF stopped aiding”, and “yaw reset”.
  • The vibration levels spiked sharply right before the disarm, likely due to impact.
  • Motor outputs all spiked to max before the crash.
  • GPS.GCrs showed fluctuating speed and possible loss of GPS quality.

What I’m trying to understand:

  • Was the crash caused by a sensor fusion failure (EKF)?
  • Did compass or GPS inconsistencies play a major role?
  • Could battery sag or vibration have contributed?

Thanks in advance for your time and support.

2

Graph the RCout’s. Thrust loss on Motor 1, Motor 2 drops to stabilize and down it goes.

No, one Motor was commanded to max due to thrust loss.

1 Like
3

Thanks again, Dave — your help really clarified a lot for me.

Just a quick question if you don’t mind:

I was using a custom mission script written with pymavlink to control the drone.

Do you think it’s at all possible that a bug in the script caused the motor 1 thrust loss?

Or from your experience, is this almost always a hardware issue — like motor, ESC, or wiring?

Blockquote

4

Yes, this is most likely.