Mavic Mini flyaway

[puksion]

Hi all, two days ago i flew with my mini, i was just ascending in the air to make some shoots and the mini just flew away which i didnt gave that controls to him, it almost crashed then it stopped itself, it was not reacting to commands. My gimbal is broken, i dont have stabilisation to record video but i can still make good photos, but that doesnt affect drone flying. Since that day im afraid to put drone in the air again. The propellers are new, there was no wind that day, and no interference as the log say, it was just right above me, antenna positions were fine, i flew in that position since i got the drone, Here is the log so if someone know what happened please let me know, the flew away happened at 1min and 2sec

Edit: Link to airdata log flight

 

[Deleted member 103366]

DJI Flight Log Viewer | Phantom Help

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Whoa!!!

 

[dawgpilot]

For starters, it looks like you took off before you had a GPS lock. That's never a good idea.

 

[puksion]

The drone was within my VLOS, isnt GPS necessary for RTH and just navigating when its too far away ? I flew in my house with propeller guards many times and it never went crazy like that

 

[Meta4]

Here is the log so if someone know what happened please let me know, the flew away happened at 1min and 2sec

The uncommanded flight with rapid acceleration and curved flight path looks very much like a yaw error which is caused by powering on and launching from within a magnetically dirty area.
The most common cause is launching from reinforced concrete.

 

[slup]

Hi all, two days ago i flew with my mini, i was just ascending in the air to make some shoots and the mini just flew away which i didnt gave that controls to him, it almost crashed then it stopped itself, it was not reacting to commands. My gimbal is broken, i dont have stabilisation to record video but i can still make good photos, but that doesnt affect drone flying. Since that day im afraid to put drone in the air again. The propellers are new, there was no wind that day, and no interference as the log say, it was just right above me, antenna positions were fine, i flew in that position since i got the drone, Here is the log so if someone know what happened please let me know, the flew away happened at 1min and 2sec

Edit: Link to airdata log flight

This looks very much like a yaw error due to powering on the Mini in a magnetic disturbed area ... if you can provide the mobile device .DAT log also we can access the sensor data. The .DAT log that belongs to this flight ends with FLY002.DAT, read up here on how to retrieve --> Mavic Flight Log Retrieval and Analysis Guide (see section 3.)

DJI Flight Log Viewer | Phantom Help

Upload and view flight logs from your DJI drones

www.phantomhelp.com

Whoa!!!

You can access a similar simulation view in Airdata ...

In "General tab", open the "Notifications tab"


In there click "HD Flight Player"


... and "Whoa!!!" -->

 

[Meta4]

The drone was within my VLOS, isnt GPS necessary for RTH and just navigating when its too far away ? I flew in my house with propeller guards many times and it never went crazy like that

You always want to wait for GPS before launching.
Without GPS you have no horizontal position holding ability and no home point and it can be blown away easily.

The homepoint was recorded 34 seconds after launching but was quite close to the launch point.
You were lucky in this case because there was little wind and you only climbed above the launch point before flying off.

 

[puksion]

This looks very much like a yaw error due to powering on the Mini in a magnetic disturbed area ... if you can provide the mobile device .DAT log also we can access the sensor data. The .DAT log that belongs to this flight ends with FLY002.DAT, read up here on how to retrieve --> Mavic Flight Log Retrieval and Analysis Guide (see section 3.)


You can access a similar simulation view in Airdata ...

In "General tab", open the "Notifications tab"
View attachment 108387

In there click "HD Flight Player"
View attachment 108388

... and "Whoa!!!" -->

Here is the DAT file, i found it

Meta4 i understand what you want to say, but how does it keeps its position when its howering inside a house with 0 satellites? i cant connect these two things, when he was outside there was no wind, it was perfect weather

 

[Meta4]

Meta4 i understand what you want to say, but how does it keeps its position when its howering inside a house with 0 satellites? i cant connect these two things, when he was outside there was no wind, it was perfect weather

Indoors there is no wind to blow the drone away.
But if you fly it forward, it has no "brakes" and keeps sliding when you centre the sticks.
That makes it very easy to crash.

 

[puksion]

Thank you for info, i will keep that in mind in the next flights, im only interested now whats gonna sensors say in DAT file,i dont know to look into that files but im awaiting slup response, thank you all for help

 

[Deleted member 103366]

but how does it keeps its position when its howering inside a house with 0 satellites?

Indoors without satellites it uses the vision sensors on the bottom of the drone, (VPS) BUT they have a limited range, something like 10m I think
VPS and GPS are entirely separate from one another

 

[slup]

Thank you for info, i will keep that in mind in the next flights, im only interested now whats gonna sensors say in DAT file,i dont know to look into that files but im awaiting slup response, thank you all for help

If we start to look at what happens with the imuYAW (Blue) & the magYaw (Green, compass) from where the AC is powered on until it passed the auto take off.

At power on the imuYaw is initialized to the same value that magYaw have ... from that moment the imuYaw degrees is the direction the AC think's it is pointing & it's with that heading the flight controller will work.

As seen here both are initialized to the same value of approx 38 degrees (left side in the chart), then the AC is carried around and rotated ... but note what happens with the magYaw (Green), it doesn't follow at all, most probably due to that the compass (magYaw) is away from the magnetic disturbance. Then jump forward to the right side of the chart just after the blue/lightblue area where the AC takes off. Here the magYaw have a heading of 67 degrees ... but the IMU think's it's heading is -8 degrees, a disagreement of nearly 75 degrees.



But so far no consequence is showing up ... you get a really late GPS lock with sufficient navhealth at 34sec into the flight & you start to gain altitude. Up on 35m height at 61 sec the AC starts to be affected by the nearly 3m/s wind coming from south west up there & needs to correct it's position ... & it's there the heading angle disagreement comes into play. As the AC don't have the correct info about how the AC is pointing it starts to apply thrust to the wrong motors to regain position ... but to the wrong motors so the position error just becomes larger & the "snowball starts to roll" & the speed increases (Black) ... & away it goes.



Below how the imuYaw was pointing (Green bar) & the magYaw (Blue bar) ... nearly a 90 degree disagreement when the flyaway starts.



Another way to visualize this is to compare the GPS velocity to the IMU velocity ... if everything is as it should they should be close to equal but that isn't the case here after 61sec ...



And in the log event stream we find already before take off ...



A very easy way to avoid incidents like this is to look at the drone icon on the map in DJI FLY app & check so it's pointing equal relative objects on the map (streets, buildings etc.) as it does in reality ... if it doesn't, power down & move to another take off spot and power up & check again.

 

[puksion]

Thank you sir very much, i didnt expected you had so much knowledge, i will be much safer now, i dont care to much about drone, i worry to not injure someone, will keep in mind all tips you gave me

 

[hiflyer201]

Thank you sir very much, i didnt expected you had so much knowledge, i will be much safer now, i dont care to much about drone, i worry to not injure someone, will keep in mind all tips you gave me

I knew he had that knowledge, and now I know that you are a good guy! happy flying