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Random mid-flight IMU error?

Mynah

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Joined
May 1, 2021
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Location
South Africa
I cannot explain how the Mini 2 disappeared from sight behind a house with no controller input from my side whatsoever. I was happily ascending after take-off, reached 30m 19.0 seconds into the flight and then the Mini 2 scooted off on its own, reaching a speed of 28.5 kmh before I realised what was happening and provided stick input to try bring it back.
I DID compare craft orientation and physical North orientation before takeoff.
Home point was registered with 17 sats locked.
There was no nearby metal above or below ground to interfere with magnetic compass.
There were no apparent crosswinds.
I managed to regain control and continued with my planned flight without further incident albeit with soiled pants. Luckily the Mini 2 was high up enough to clear the house.
I suspect the same thing happened to my other Mini 2, only it was still low enough to crash into my neighbour's house. (My DJI supplier repaired the crash damage under warrantee after looking at the log files even though I was using a third party app at the time.). The thread about that disaster can be viewed here: Help me understand Mini2 crash.
Am I correct in suspecting IMU error or am I overlooking something obvious?
Input would be greatly appreciated.
The log file:
 
Before I look at the flight data, I think you aren't really asking about an IMU error at all.
It seems in the end of your other incident, you were confused and referred to a yaw error as an IMU error and have done it again in this thread.
 
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Input would be greatly appreciated.
Your drone shows some indications of a yaw error during the flight.
It slowly picks up speed from 16.8 seconds without any corresponding joystick input.
From 20.1 seconds the heading data suggests the drone is rotating anti-clockwise without any rudder input and the speed increases without joystick input.

The data shows the drone pointing towards the NNW (328 degrees) at startup.
What direction was actually facing?
What was the surface you launched from?
 
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Your drone shows some indications of a yaw error during the flight.
It slowly picks up speed from 16.8 seconds without any corresponding joystick input.
From 20.1 seconds the heading data suggests the drone is rotating anti-clockwise without any rudder input and the speed increases without joystick input.

The data shows the drone pointing towards the NNW (328 degrees) at startup.
What direction was actually facing?
What was the surface you launched from?
My thanks for pointing out the correct terminology and confirming that the Mini 2 did indeed do its own thing without user input for a while there.
I determined general North using a calibrated phone compass since I was travelling and not launching from my usual known surroundings, I did confirm drone orientation before takeoff, lesson learnt from previous suspected yaw error. Accuracy of orientation within +- 20 degrees from true North, best I can do without resorting to detailed topo map and handheld compass before every drone flight.
Take-off surface was small paving brick, too small to contain steel re-enforcing and well away from any structures, again, lesson learnt from previous experience and sound advice.
Nothing more I can do to prevent future tragedy directly after takeoff other than observing above and making a point of gaining safe altitude asap like I already do to allow manoeuvring space for the Mini 2 to perform its unwanted antics.
I am considering a DJI warrantee workshop look-over before I have to send them a crashed Mini 2 again.
Thank you once again for your valuable expert input, much appreciated.
 
I determined general North using a calibrated phone compass since I was travelling and not launching from my usual known surroundings, I did confirm drone orientation before takeoff, lesson learnt from previous suspected yaw error. Accuracy of orientation within +- 20 degrees from true North, best I can do without resorting to detailed topo map and handheld compass before every drone flight.
There's no need to find North or any other compass direction.
If you were trying to match your drone's heading with compass north, the drone was pointing 32 degrees west of north as its heading was 328 degrees, rather than 360 degrees.

All you need to do is make sure that the alignment of the drone matches the alignment of the arrowhead drone icon in the app's map view.
In this example, I don't know where North is, but I placed the drone on the road edge pointing in the same direction as the road and the map view shows the drone icon pointing the same way as the real drone is.
You can use any map feature that's easy to see like a river or a road.
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