ArduCopter Failed motor detect and warning

Caleb Woodruff

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May 1, 2015, 2:31:05 PM5/1/15

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A few days ago I had a crashed of my Octa Quad setup due to a failed motor. Post crash investigation showed that the motor failed during the previous flight and some combination of battery voltage, wind, and magic fairies kept the thing flying long enough to hover for about a minute in the subsequent flight before falling.

The RCOU log of the previous flight shows exactly where the motor failed on landing:

The bloom during descent is the Pixhawk maintaining stability after losing >50% lift on the right rear arm. The prop windmilled enough that I didn't notice it and some sort of intermittent connection made the spin check before the next flight look ok.

I'm considering adding a monitor to the RCOU in the pixhawk firmware that will send a motor failure warning over mavlink when the motor PWM shows that sort of split. Clearly the warning will also get triggered during hard yawing etc but the pilot will know about those events enough to ignore the warning. Can anyone think of an easier way to implement this?

Thanks,

--Caleb

Lucas Porto

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Oct 23, 2016, 9:09:59 PM10/23/16

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Did you solve that ?

I think i have the same problem...

Holger Steinhaus

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Oct 24, 2016, 1:46:31 PM10/24/16

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This issue is subject of a rather old pull request submitted by me: https://github.com/ArduPilot/ardupilot/pull/3672 . The idea behind the PR is not only to report unusual motor load via MavLink, but also via RC telemetry (thanks to Tom for the idea). I have a script on my radio that triggers the vibration alert on both high or low motor loads. That way you instantly "feel" if your vehicle is on the way to leave the safe flight envelope, may it be due to motor failure, excessive speed or inappropriate weather.

Never got that one merged and it seems that most folks flying copters today are perfectly ok with losing a vehicle from time to time. Since issues like this one forced me into flying my own fork and I currently don't have any pressure to upgrade it, I did not really maintain the PR so it currently does not merge with the latest code.