Mavic air loosing altitude

[LSU1]

Was flying around the house this afternoon, got up to about 100 ft and suddenly dropped to about 60 ft. I immediately hit the drone up lever and finally went back up. Any ideas why this might of happened?

 

[sar104]

Not without the flight log.

 

[LSU1]

Ok, going to try and figure how to post it!

 

[LSU1]

DJI Flight Log Viewer | Phantom Help

Upload and view flight logs from your DJI drones

www.phantomhelp.com

 

[LSU1]

Is this what you need?

 

[sar104]

There's definitely something strange going on there - the behavior that you mentioned is apparent:



The cause of those drops and climbs appears to be IMU-related - the altitude variations during that part of the flight don't agree with the vertical velocities. Comparing the vertical velocity integrated with respect to time to the FC-computed height shows the disagreement clearly:



This really needs the mobile device DAT file ending FLY049.DAT in order to look at the raw IMU and barometric data.

 

[LSU1]

Thank you so much! I just recalibrated my imu. Hope that will help. And will try to get the file above for you if I can figure out how

 

[LSU1]

Can you help me figure out how to get you that file. I found it and saved it to my Google drive.

 

[sar104]

Can you help me figure out how to get you that file. I found it and saved it to my Google drive.

You can share a Google Drive link or you can just upload it to this site.

 

[LSU1]

20-03-07-05-24-00_FLY049.DAT

drive.google.com

 

[LSU1]

Let me know if that worked

 

[sar104]

Let me know if that worked

It didn't because you didn't grant access. It might be simpler just to upload the log to this site using the "Attach files" button.

 

[LSU1]

20-03-07-05-24-00_FLY049.DAT

drive.google.com

 

[LSU1]

Ok try now

 

[LSU1]

Ok,maybe this will work

 

[sar104]

20-03-07-05-24-00_FLY049.DAT

drive.google.com

Well it's a bit clearer now, but another case where the active IMU seems to compute a trajectory that is not supported by any of the sensors. Neither of the accelerometers nor barometric reading supported the computed height solution from IMU(1), which was completely incorrect. The result was that the aircraft actually climbed higher than you commanded by throttle, and then the FC attempted to fix that by bringing it back down:

 

[LSU1]

Wow, any suggestions? And thanks for hanging in there with a newbie!!!!! Much appreciated

 

[sar104]

Wow, any suggestions? And thanks for hanging in there with a newbie!!!!! Much appreciated

Not really. Have you seen any indications of previous anomalous behavior? You could do an IMU calibration, but the sensors seem good. This looks more like a computational hiccup.

 

[LSU1]

No this was the first time!!! Just had me grip the controller a little harder!!! Lol!!! I have calibrated it,will try it in the morning!! Thanks for your time

 

[Deleted member 94047]

@LSU1, glad you got out of that unscratched. Is this another hiccup or do you really live in a place -112m below sea level? From the DAT event stream log:

25.952 : 7460 [L-HOME]Update. lati:34.1482575 longti:-77.8899790 alti:-112.26

@sar104, I don't think i have seen this before. What is "vgz"?

74.673 : 9902 [L-FDI][FDI] ns atti(0) vgz is outlier
74.673 : 9902 [L-FDI][FDI] ns atti(1) vgz is outlier