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Lost Mavic Pro Platinum - Anyone ca figure why it didn't return to home?

sar104

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#3
It didn't return home because it was in ATTI mode due to multiple yaw errors. If you want to know more than that then you will need to post the mobile device DAT file, which includes the magnetometer data.

How to retrieve a V3.DAT from the tablet
 
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#4
It didn't return home because it was in ATTI mode due to multiple yaw errors. If you want to know more than that then you will need to post the mobile device DAT file, which includes the magnetometer data.

How to retrieve a V3.DAT from the tablet
Please upload your TXT flight log here and post a link back here. You'll find instructions for locating your TXT flight log at that link.
Trying, but get: "Error: Upload timed out." whenever I try.
 
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#8
It didn't return home because it was in ATTI mode due to multiple yaw errors. If you want to know more than that then you will need to post the mobile device DAT file, which includes the magnetometer data.

How to retrieve a V3.DAT from the tablet
To upload the DAT file, which is the one with the most useful data in these kinds of cases, you will just need to change the file extension from DAT to txt.
Here is the txt from DAT file attached.
 

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#15
Were you seeing all the popup warnings about compass and yaw error on DJI Go 4 when you were flying?
Not when I took off, later on they showed but then it seemed to late. Would the drone just hoover out over the water until it landed in water if RTH didn't work?
 

RayOZ

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#16
The error seems to have been occurring even in mid-flight, not just the end. I'd be worried if the system is encountering these errors and not have notification for the operator. No idea what RTH would do, since it has lost GPS, it doesn't know where it is, so it won't know where to go. If you can recover the drone, the logs inside might shed some light. Considering it seems to have gone into ATTI mode over water, it could potentially just hover till it drop. Too bad you lost connection. If you still had connection, you'd be able to manually fly over land, and land somewhere to retrieve.
 

sar104

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#17
That looks like the problem. The compass initialized the IMU yaw value at almost due north, which suggests that there was magnetic interference at the location where you took off:

18-07-10-10-15-14_FLY037_01.png

That led to significant discrepancies after takeoff between the compass (magnetic yaw) and the updated IMU yaw derived from the rate gyros. That, in turn, is the cause of the yaw errors and the switch to ATTI mode, after which RTH was not possible.

We can also look at the difference between IMU yaw and magnetic yaw as a function of magnetic yaw:

18-07-10-10-15-14_FLY037_02.png

This does not have the characteristic 2π (360°) periodic variation that appears when the issue is a compass calibration problem - for example this is the equivalent comparison in just such a case that I'm looking at for a different aircraft:

18-07-10-10-15-14_FLY037_03.png
 

macoman

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#18
That looks like the problem. The compass initialized the IMU yaw value at almost due north, which suggests that there was magnetic interference at the location where you took off:

View attachment 41924

That led to significant discrepancies after takeoff between the compass (magnetic yaw) and the updated IMU yaw derived from the rate gyros. That, in turn, is the cause of the yaw errors and the switch to ATTI mode, after which RTH was not possible.

We can also look at the difference between IMU yaw and magnetic yaw as a function of magnetic yaw:

View attachment 41925

This does not have the characteristic 2π (360°) periodic variation that appears when the issue is a compass calibration problem - for example this is the equivalent comparison in just such a case that I'm looking at for a different aircraft:

View attachment 41926
I always love to see your analysis that prove your knowledge in the area. Very well done sir!!!
 
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#20
That looks like the problem. The compass initialized the IMU yaw value at almost due north, which suggests that there was magnetic interference at the location where you took off:

View attachment 41924

That led to significant discrepancies after takeoff between the compass (magnetic yaw) and the updated IMU yaw derived from the rate gyros. That, in turn, is the cause of the yaw errors and the switch to ATTI mode, after which RTH was not possible.

We can also look at the difference between IMU yaw and magnetic yaw as a function of magnetic yaw:

View attachment 41925

This does not have the characteristic 2π (360°) periodic variation that appears when the issue is a compass calibration problem - for example this is the equivalent comparison in just such a case that I'm looking at for a different aircraft:

View attachment 41926
Wow, thanks for the reply! You really know your stuff.
 
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