Motor Error mid-flight, but always recovers.

[sharprez]

I looked around the forum and I did not find an answer to this problem.
Mini SE, it has been crashed... I got the ESC 3xxxx error (cant remember the exact code), I replaced the ESC board and now it flies! But..... (probably more damage)...
I got a Motor failure error, and I see the video jerk around for a split second, and then it recovers (no crash).
I experimented flying low over tall grass (soft landing for test dummies) to see if I could replicate the problem, and I did (3 times, but no crash).
The error occurs when in sport mode; descending and going backwards as fast as possible.
Looking at the front of the Mini SE, the left rear would drop and then tilt in the air as if the left rear motor failed for an instant, and then immediately recover.
How can I determine which motor is failing by visual flight inspection? I'm guessing the left rear, but is there any way to positively identify the bad motor? Physics may not be what they appear to be.

 

[ACDan]

I looked around the forum and I did not find an answer to this problem.
Mini SE, it has been crashed... I got the ESC 3xxxx error (cant remember the exact code), I replaced the ESC board and now it flies! But..... (probably more damage)...
I got a Motor failure error, and I see the video jerk around for a split second, and then it recovers (no crash).
I experimented flying low over tall grass (soft landing for test dummies) to see if I could replicate the problem, and I did (3 times, but no crash).
The error occurs when in sport mode; descending and going backwards as fast as possible.
Looking at the front of the Mini SE, the left rear would drop and then tilt in the air as if the left rear motor failed for an instant, and then immediately recover.
How can I determine which motor is failing by visual flight inspection? I'm guessing the left rear, but is there any way to positively identify the bad motor? Physics may not be what they appear to be.

Buy a new drone to video the drone in question. Video analysis should verify which motor cut out.

Logical reason to own a second drone.

 

[slup]

...How can I determine which motor is failing...

If your craft drops a corner mid flight without any sudden outside coming forces affecting it ... it means that the same corner loses thrust due to either prop or motor problems (... or electronics that commands the motor).

It's easy to see which corner it is out from the flight log ending with .TXT that is stored in the mobile device you flew with.

Go here ---> DJI Flight Log Viewer | Phantom Help , scroll down a bit & they describe where to find the log. Once retrieved & copied to your computer, upload it to that web page. When uploaded they will provide a link... copy that & come back here & share it in a new post.

 

[sharprez]

If your craft drops a corner mid flight without any sudden outside coming forces affecting it ... it means that the same corner loses thrust due to either prop or motor problems (... or electronics that commands the motor).

It's easy to see which corner it is out from the flight log ending with .TXT that is stored in the mobile device you flew with.

Go here ---> DJI Flight Log Viewer | Phantom Help , scroll down a bit & they describe where to find the log. Once retrieved & copied to your computer, upload it to that web page. When uploaded they will provide a link... copy that & come back here & share it in a new post.

I know its been a while... but here is the link to my uploaded flight log.

DJI Flight Log Viewer | Phantom Help

Upload and view flight logs from your DJI drones

www.phantomhelp.com

I want to determine which motor is having problems.

 

[slup]

...I want to determine which motor is having problems.

Quickly glanced over the log for any abnormal uncommanded craft movement & found one when you were bouncing up & down quite low ...

You apply full throttle for ascend but in the middle of that stick command the craft pitches down, roll over to the right & yaws quickly CCW & loses some height ... then it straightens up & yaws back CW.

You can see the movements in the zoomed in chart here below ...

The blue dashed is your throttle stick for ascend (neutral stick have value 1024)
The purple dashed is some rudder input for CW rotation you probably do by mistake (neutral stick have value 1024)
The green is the vertical speed, negative value = ascend, positive = descend
The yellow is the pitch angle, positive value = nose up, negative = nose down
The magenta is the roll angle, positive value = roll right, negative = roll left
The black is the yaw angle from North=0 on a +/-180 scale, CW = positive value, CCW = negative value

(Click on the chart to make it larger)


Have above placed the chart marker at 258,9sec into the flight where the incident starts ...

The craft pitches nose down = either of the 2 front corners stops generating thrust
The craft rolls to the right = either of the 2 right corners stops generating thrust

That narrows it down to the front right corner ...

And a final check out from the uncommanded CCW rotation.

The front left+rear right generate CCW torque & the front right+rear left generate CW torque ... so if the front right stops generating thrust the craft will be rotating CCW as the torque balance will be 2xCCW - 1xCW.

In the .TXT log message stream we also find this ...

 

[careless]

Hope this helps but I had the same problem with my mini so I replaced the props and it never happened again and I couldn't see anything wrong with the motors or props.