Crash. Now what?

[RoboticTundra]

Per earlier suggestions did a Compass, IMU and RC calibration this morning. Ran some test flights near my home and all went well. Took the MPP to a home building site about 5 miles away to take some video. All looked good at takeoff. As it was rising it got to about 2m and then suddenly began going backwards and crashed in to some brush. I found it upside down in dirt.

Airdata indicates good GPS at start and then declining as it went backwards.



I assume vacuum off good (dirt in vents) and do a visual check? Turn on and see what Go4 says?

I'd really like to know what happened. I don't think I pulled back on the right stick but may have. Download .DAT files from it and post here?

Thanks all,

 

[Mossiback]

The files will show stick movements. I would also use some compressed air on it and take off the props and see if any dirt got down in the motors.

 

[RoboticTundra]

Am I correct that I use DJI Asst 2 to retrieve the .DAT file from the Mavic? Then upload the .DAT to dropbox? Or convert from .DAT to .CSV or ?? and then upload?

I was using Litchi. How useful are the Litchi log files? I assume the log file on the Mavic has more granular/accurate data?

Thanks,

 

[MavicCF]

Am I correct that I use DJI Asst 2 to retrieve the .DAT file from the Mavic? Then upload the .DAT to dropbox? Or convert from .DAT to .CSV or ?? and then upload?

I was using Litchi. How useful are the Litchi log files? I assume the log file on the Mavic has more granular/accurate data?

Thanks,

Yes, you use Assistant 2 to retrieve the AC DAT. Dropbox would be perfect. I haven’t used the Litchi logs much, so I can’t recall how useful they are. You may as well upload them too though. -CF

 

[RoboticTundra]

Having difficulty getting the .DAT files. I'm using DJI Assistant v1.2.3 on MacOS 10.13.4.

- It connects to my MPP OK and indicates I have latest software and give a couple of regression options.
- I choose Flight Data
- Click 'confirm' in the box for Enter the Flight Record page.
- The small box w/ the confirm option closes but then the only option on the mostly blank page is 'Open Data Viewer'.

1) I clicked around Finder but was unable to locate the DJI FLY LOG directory anywhere.

2) Entered Data Viewer (v1092) and clicked on the 'load' option which showed what appears to be the directory structure on the MPP's internal SD card but no .DAT files to be found in any of the folders.

???

Thanks,

 

[RoboticTundra]

Here's the csvViewer image from Litchi. I assume these are stick movements:



I assume elevator is left stick up/down for ascend/descend and throttle is right stick up/down for forward/back? If so then there seems to be some confusion as the Mavic ascended based on throttle forward?

 

[MavicCF]

Here's the csvViewer image from Litchi. I assume these are stick movements:

View attachment 37080

I assume elevator is left stick up/down for ascend/descend and throttle is right stick up/down for forward/back? If so then there seems to be some confusion as the Mavic ascended based on throttle forward?

Swap what you said around and it’s correct, throttle makes it ascend/descend and elevator makes it go foreword/back.
I'll try downloading it now to check it out.

 

[MavicCF]

Oh, never mind, I thought you had posted the Litchi .Csv but it looks like its just pictures. Any chance you could upload the log?

 

[RoboticTundra]

Yep.

 

[MavicCF]

Yep.

Do you happen to remember which direction the Mavic was facing when you took off? East, West North, or South?

 

[Simmo]

I dont know what that pitch wobble is??
Gps wasn't a problem I bellieve?

 

[Simmo]

Ahh was the pitch wobble when it was in the bush??

Edit: So if the crash was around 11 secs, it was flown backwards into the bush???

Compass error?

 

[MavicCF]

I was wondering about compass errors as it almost appears to have started the "toilet bowl" effect before it encountered the bush. Were you recording video OP?

 

[MavicCF]

Here is the Phantom Log Viewer for anyone who wants it. I wonder if @sar104 is around?

 

[RoboticTundra]

IIRC it was facing NNW at takeoff. It slowly rotated to N and going backwards was almost due north to maybe +5°.

It started going backwards at about 6 seconds in to the video. Contact with bushes (and so crash) at about 8 seconds. Upside down digging dirt with props at about 10 seconds.

I do have video. I'll need to setup a youtube account later tonight.

 

[MavicCF]

IIRC it was facing NNW at takeoff. It slowly rotated to N and going backwards was almost due north to maybe +5°.

It started going backwards at about 6 seconds in to the video. Contact with bushes (and so crash) at about 8 seconds. Upside down digging dirt with props at about 10 seconds.

I do have video. I'll need to setup a youtube account later tonight.

The headings you mention are what you see in the video, not the logs? (just making sure)

 

[RoboticTundra]

The headings you mention are what you see in the video, not the logs? (just making sure)

Yes.

I tried posting a zip of the video but not unexpectedly too large. S/b on youtube later tonight.

 

[Simmo]

Added Yaw.

 

[BudWalker]

Having difficulty getting the .DAT files. I'm using DJI Assistant v1.2.3 on MacOS 10.13.4.

- It connects to my MPP OK and indicates I have latest software and give a couple of regression options.
- I choose Flight Data
- Click 'confirm' in the box for Enter the Flight Record page.
- The small box w/ the confirm option closes but then the only option on the mostly blank page is 'Open Data Viewer'.

1) I clicked around Finder but was unable to locate the DJI FLY LOG directory anywhere.

2) Entered Data Viewer (v1092) and clicked on the 'load' option which showed what appears to be the directory structure on the MPP's internal SD card but no .DAT files to be found in any of the folders.

???

Thanks,

I believe you want the Data Upload option not the Flight Data option. Look here for instructions about retrieving the .DAT from the Mavic. Since this is one of the first flights on your Mavic you have a good chance of retrieving the .DAT.

 

[MavicCF]

Ok, I'm still learning about compass errors and diagnosing them, so this is going to be my first real stab at it. All you experts feel free to jump in and correct and discredit this graph. I'm practicing (sorry OP ) so here we go.

The Mavic's yaw aligned on a heading of approximately 140 degrees or facing SE. In actuality, the heading was approximately 35 degrees or NE (measured on Google Earth). This caused the flight controller to be confused upon take off because its inputs resulted in completely different results than it intended. That's about as "techy" as I can get in my explanation, so here is the graph.
Again, experts feel free to tear this apart! -CF