Crash during autotune

Log Analysis -- deprecated Copter Logs -- deprecated
1

Hi,

perhaps someone can help me discover the cause of a surprising crash my little quad (310mm) suffered today. It happened during autotune: the roll tuning was just over and the pitch tuning began when the quad suddenly lost control and fell to the ground.

I really have no idea what happened. After the crash, I noticed that the two “rear” motors don’t turn any more, but only shake and clatter. I don’t know, if this was a cause or a result of the crash. The log didn’t give me a clue. (Log attached: 03autotune-crash.bin.log)

A flight before the autotune session went absolutely ok. (Log attached: 02everything-ok.log)

Some facts / hints / questions:

  • Vibrations are ok (Log attached: 01VibsOK.bin)

  • It’s a fun quad therefore it as no GPS.

  • The compassmot result was quite bad because of the power board beneath the APM. But I don’t need the compass because I only fly in Stab, Acro and Alt Hold mode. So it doesn’t matter.

  • Before all that happened I had replaced the old SimonK ESCs with new, small KISS ESCs (18A). Could the KISS ESCs be the problem?

  • As power supply for the APM I use a 5V BEC. In the log I saw that Vcc varies between 4,92 and 5.07 volts. Is this a problem?

  • Motors: Flyduino X2208v2, 1100kV, Props: HQProp 8x5, Battery: 4S 2200mAh, Weight: 900g

All the best, Markus

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Update: I looked at the broken motors in the meantime: both suffered one or two cuts of the wire (inside the motor, directly at the coil). Maybe this happened during the crash. But then I still don’t know what made the quad crash…

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Unfortunately you logs are set quite low but you do have a couple of EKF errors. these occur after the initial descent and when roll goes crazy…so maybe due to the crash rather than the cause.

Vcc looks ok to me.

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[quote=“RabbitStu”]Unfortunately you logs are set quite low but you do have a couple of EKF errors. these occur after the initial descent and when roll goes crazy…so maybe due to the crash rather than the cause.
[/quote]
These EKF errors occured after the quad was fallen to the ground.

Other question: Can the APM 2.5 handle it, if I enable the “Nearly All” Logging? Or will it be too slow for that. There were suggestions not to enable too much logging, but I don’t know if this counts only for octos or for quads also. In my case it’s a fun quad, so I fly it fast and aggressive. A problem for the APM if it has to log too much?