Help analyzing log file

[batboy]

Hello,

While flying yesterday my Mavic Pro decided to fly into a tree, fortunately it didn't get stuck, it tumbled down and fell onto a snowy slope.
The damage wasn't to bad, the gimbal was out of position and the flex cable ripped, the rear right leg was slightly damaged as well.

I have downloaded the DAT-file from the Mavic and tried to analyse what went wrong, but i need some help.
It was pretty cold outside (my fingers where turning to ice), so i decided to use the RTH-button.
When the Mavic was about 10m above home point, it suddenly started to fly backwards straight into a tree.

I was not controlling the Mavic at all, as it was in RTH-mode, i was just waiting for it to land so it was definitely not a user error.

When i look at the data in CsvView it is obvious something happened but i don't understand what.


Can someone check the logfile and maybe analyse it better then me?
Logfile: FLY060.DAT



Thanks
/ Joakim

 

[naturecannon]

Three 8330s ????

 

[batboy]

Three 8330s ????

The only thing left of the fourth prop is one of the three small plastic tabs that lock the prop in (in the photo).
I don't know if the prop came off when it hit the tree or earlier than that, i couldn't find it on the ground (it was getting dark).


I don't know, what do you think?

/j

 

[sar104]

I need to take a closer look at the data, but it reported an IMU/compass discrepancy as it descended which resulted in loss of control. It was also reporting vibration issues, but that was probably unrelated.

 

[sar104]

OK - on further analysis I have no idea what caused this. The aircraft was in autolanding mode up to the collision with the tree. There were no stick inputs to confuse it, OA did not activate, and the FC had achieved the HP location. As the aircraft continues its descent, the onset of motion away from the homepoint is clearly recorded starting at around 140 s until the crash at 143 s:–




There were no IMU errors, particularly magnetic issues prior to the event:–



The motion was caused by pitch and roll adjustment, not drift:–



The pitch and roll were activated by motor speed changes - specifically backward (+) pitch by increases in the front motor speeds and decreases in the back motor speeds:–



The motor speed adjustments were commanded by the FC:–



So - I can see why it moved backwards and crashed, but I cannot see why the FC caused that to happen. I must be missing something here.

@BudWalker?

 

[BudWalker]

Hello,

While flying yesterday my Mavic Pro decided to fly into a tree, fortunately it didn't get stuck, it tumbled down and fell onto a snowy slope.
The damage wasn't to bad, the gimbal was out of position and the flex cable ripped, the rear right leg was slightly damaged as well.

I have downloaded the DAT-file from the Mavic and tried to analyse what went wrong, but i need some help.
It was pretty cold outside (my fingers where turning to ice), so i decided to use the RTH-button.
When the Mavic was about 10m above home point, it suddenly started to fly backwards straight into a tree.

I was not controlling the Mavic at all, as it was in RTH-mode, i was just waiting for it to land so it was definitely not a user error.

When i look at the data in CsvView it is obvious something happened but i don't understand what.
View attachment 27220

Can someone check the logfile and maybe analyse it better then me?
Logfile: FLY060.DAT

View attachment 27221

Thanks
/ Joakim

It seems that this .DAT is must be the second one created for a flight. Is there a FLY059.DAT? Please Dropbox and post that one.

 

[batboy]

OK - on further analysis I have no idea what caused this. The aircraft was in autolanding mode up to the collision with the tree. There were no stick inputs to confuse it, OA did not activate, and the FC had achieved the HP location. As the aircraft continues its descent, the onset of motion away from the homepoint is clearly recorded starting at around 140 s until the crash at 143 s:–

[8<]

So - I can see why it moved backwards and crashed, but I cannot see why the FC caused that to happen. I must be missing something here.

Thank you for the detailed explanation, much appreciated.

It seems that this .DAT is must be the second one created for a flight. Is there a FLY059.DAT? Please Dropbox and post that one.

You are correct.
Link is here: FLY059.DAT (300MB)

If i recall correctly, i started flying with the DJI app, but decided to land and switch to Litchi instead.
Because the ground was covered with snow i landed on a small table (probably made of metal), and i got a notification in the app of a compass error.
I calibrated the compass but the app crashed while doing it, so i restarted the app and did a new calibration without problems.

I took off again (not from the table) and successfully shot a 360 panorama with Litchi.
The crashed happened when it was about to land from this second flight.

First flight with Go4: DJI Flight Log Viewer - PhantomHelp.com
Second flight with Litchi: DJI Flight Log Viewer - PhantomHelp.com

/ Joakim

 

[BudWalker]

Thank you for the detailed explanation, much appreciated.



You are correct.
Link is here: FLY059.DAT (300MB)

If i recall correctly, i started flying with the DJI app, but decided to land and switch to Litchi instead.
Because the ground was covered with snow i landed on a small table (probably made of metal), and i got a notification in the app of a compass error.
I calibrated the compass but the app crashed while doing it, so i restarted the app and did a new calibration without problems.

I took off again (not from the table) and successfully shot a 360 panorama with Litchi.
The crashed happened when it was about to land from this second flight.

First flight with Go4: DJI Flight Log Viewer - PhantomHelp.com
Second flight with Litchi: DJI Flight Log Viewer - PhantomHelp.com

/ Joakim

Thanks for getting FLY059. I wanted to see if there were problems previously, but I didn't see anything. The compass errors all occurred while on the ground or after the crash into the tree. So they are irrelevant. Like @sar104 I didn't see any reason why the FC would have commanded backing away from the home point.

I recall another incident where something similar happened. The guys looking at it concluded that the landing protection was on and it didn't like the landing site. That, or it thought the landing site didn't look like the site it launched from. I don't know much about the landing protection system. I always ask @msinger . Maybe he should take a look. Just spit balling here but maybe the launch site image it was using came from the first launch and not the second.