Crashed MA and I don’t know why suddenly lost control with some IMU errors coming up

[CoreyG]

I was over water and everything went funky and was lucky it went down over land is there something wrong with my drone? or is this something that happens? Im worried it will happen again
My drone is a little scratched up but otherwise seems all good I changed the props it had two errors any help would be great

 

[Bigbird48]

First I would check all the motors for sand , grit what ever. Then I'd calibrate the IMU and the compass.
then go to a big open space , start it up hover make sure you have no compass errors and good sat locks then fly around close for a while and make sure it all functions correctly.

 

[CoreyG]

Thanks mate I have done that but im worried it’s going to do it again I would like to know what caused it so I can avoid it happening again is my MA faulty should I be trying to get a replacement how does an expensive drone just fall out of the sky if it was something I’ve done I’d be happy to own it but as far as I’m aware I didn’t cause it

 

[Bigbird48]

I would guess you had a compass error caused by something magnetic near were you took off from. post your data and text logs here and some of the experts can read the data and tell you exactly what happened.

 

[Bigbird48]

Please post your logs so we can find out what happen and prevent it from doing it again.

 

[kaitokid535]

Aside from your IMU and Compass calibration, make sure to calibrate your sensors using DJI Assistance app.

Here's an official tutorial on how to do it:

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[CoreyG]

Thanks for your help I’m not quite sure how to post logs I’m doing it of my iPhone

 

[Bigbird48]

maybe ask in the general discussion forum , Im not sure how to do it either

 

[Simmo]

Thanks for your help I’m not quite sure how to post logs I’m doing it of my iPhone

Follow the instructions here, and post a link back here..

DJI Flight Log Viewer | Phantom Help

Upload and view flight logs from your DJI drones

www.phantomhelp.com

 

[CoreyG]

Thanks for your help hopefully this works

 

[sar104]

Thanks for your help hopefully this works

That's not a flight log. You need to retrieve the txt log and/or the DAT file:

TXT log: DJI Flight Log Viewer | Phantom Help

Mobile device DAT file: How to retrieve a V3.DAT from the tablet

 

[CoreyG]

Hi mate thanks for your help i am a bit out of my depth hopefully ive got it this time.

 

[CoreyG]

and this one

 

[Meta4]

Hi mate thanks for your help i am a bit out of my depth hopefully ive got it this time.

That's a flight log but it's one from a couple of weeks ago (May 31).
It did not go over water and appears to have returned without incident: DJI Flight Log Viewer - PhantomHelp.com

 

[CoreyG]

hi mate sorry for the stuff around this should be the one

 

[sar104]

hi mate sorry for the stuff around this should be the one

There are some serious IMU errors in that flight record. Comparing the position and velocity data shows large discrepancies starting at 80 seconds:



It doesn't appear to have been triggered by yaw, which suggests that it wasn't a compass issue. It really needs the DAT file, which should be FLY050.DAT.

Mobile device DAT file: How to retrieve a V3.DAT from the tablet

 

[CoreyG]

Thanks for looking at that for me I will put that dat file up when I get home this afternoon much appreciated

 

[CoreyG]

What can cause errors like this?

 

[CoreyG]

hi mate is this the one.

 

[BudWalker]

There are some serious IMU errors in that flight record. Comparing the position and velocity data shows large discrepancies starting at 80 seconds:

View attachment 75448

It doesn't appear to have been triggered by yaw, which suggests that it wasn't a compass issue. It really needs the DAT file, which should be FLY050.DAT.

Mobile device DAT file: How to retrieve a V3.DAT from the tablet

It kinda looks like an instability in the algorithm computing the IMU velocities. As you said it starts around 80 secs but really gets going around 89 secs. The GPS derived velocities are pretty smooth but the IMU velocities start oscillating with an offset of 180°. Like what you'd expect if a gain were to high.


Kinda interesting to look at the IMU derived path (green) as it shows the oscillation.