Compass error, Yaw error, IMU error and so on.

Jnse · Jun 9, 2018

Hi
When i fly my Mavic Pro last night i got a lot of compass error, GPS error, Yaw error, IMU error and even "Weak GPS Signal", but it was connected to 23 satellites, so it should not be weak/bad GPS-signal.
What could the reason be for all this errors?
I landed the Mavic and restarted it and flied a little more, now without any errors.

Here is the link to the logviewer: DJI Flight Log Viewer - PhantomHelp.com
And here is the DAT-file from the AC (i think it's the right one): Dropbox - DJI_ASSISTANT_EXPORT_FILE_2018-06-09_09-06-01.DAT

Any help would be appreciated

Simmo · Jun 9, 2018

Massive errors?! No military stuff around you?? (Whats that big area to the south west?)

Jnse · Jun 9, 2018

No military stuffs nearby but a military radar ~20km from here. (My Phantom 2 Vision have never behave strange here).
The area southwest is LKAB, a mining company.

Why do GPS stops working only because the compass gets error?
(the drone should be able to fly home no matter which way is back/front of it, so why does it "turn off" GPS just because of that?)

sar104 · Jun 9, 2018

Jnse said:
Hi
When i fly my Mavic Pro last night i got a lot of compass error, GPS error, Yaw error, IMU error and even "Weak GPS Signal", but it was connected to 23 satellites, so it should not be weak/bad GPS-signal.
What could the reason be for all this errors?
I landed the Mavic and restarted it and flied a little more, now without any errors.

Here is the link to the logviewer: DJI Flight Log Viewer - PhantomHelp.com
And here is the DAT-file from the AC (i think it's the right one): Dropbox - DJI_ASSISTANT_EXPORT_FILE_2018-06-09_09-06-01.DAT

Any help would be appreciated

Those errors were all caused by compass problems. The IMU yaw was initialized after startup from compass 1 at -1°, but compass 2 disagreed at -26°. It appears that you were moving the aircraft around as you powered it up and immediately afterwards. There was significant disagreement after initialization between the IMU yaw and both compasses:

In unwrapped yaw space the early motion disagreement is even more obvious:

It's quite possible that this was simply due to the power up movement and possible magnetic interference. I would test that by placing it on the ground, powering up without moving it, and then flying and retrieving the DAT file for comparison.

Jnse · Jun 9, 2018

Oh i might have done that, will try again without doing anything while powering it up.
Thanks for the help

Jnse · Jun 9, 2018

BTW, what software do you open the DAT file with?

I did a new flight this evening and now everything worked, not a single warning (just high wind).
But i havent got time yet to copy the files to my PC.

sar104 · Jun 9, 2018

Jnse said:
BTW, what software do you open the DAT file with?

I did a new flight this evening and now everything worked, not a single warning (just high wind).
But i havent got time yet to copy the files to my PC.

Converted to CSV using DatCon, visualized in Igor Pro.

Jnse · Jun 10, 2018

This is the data from the new flight.
I never saw any error message at the screen, except the "High wind" warning, but here was a compass error when looking at the DJi Logviewer.
DJi Logviewer: DJI Flight Log Viewer - PhantomHelp.com (Compass error at 6m 16.6s)
DAT-file from the AC: Dropbox - DJI_ASSISTANT_EXPORT_FILE_2018-06-10_07-45-41.DAT

Why did i get compass error this time?
I have not yet understood how "Igor" works, but i will try to figure it out

sar104 · Jun 10, 2018

Jnse said:
This is the data from the new flight.
I never saw any error message at the screen, except the "High wind" warning, but here was a compass error when looking at the DJi Logviewer.
DJi Logviewer: DJI Flight Log Viewer - PhantomHelp.com (Compass error at 6m 16.6s)
DAT-file from the AC: Dropbox - DJI_ASSISTANT_EXPORT_FILE_2018-06-10_07-45-41.DAT

Why did i get compass error this time?
I have not yet understood how "Igor" works, but i will try to figure it out

Have you calibrated the compasses? The compass 2 looks bad.

Jnse · Jun 10, 2018

sar104 said:
Have you calibrated the compasses? The compass 2 looks bad.

View attachment 39856

Yes i did calibrate it yesterday before the flight

I can try to calibrate it again and take a short flight (to keep down the file size).

Jnse · Jun 10, 2018

New Flight.
Logviewer: DJI Flight Log Viewer - PhantomHelp.com
DAT-File from AC: Dropbox - DJI_ASSISTANT_EXPORT_FILE_2018-06-10_18-29-53.DAT (i think it's the right file, i had some problems with dropbox)

The 2 compasses does not show the same value, even after a new calibration.
How much can they be off before it's bad?
In the DJi Go4 app, i can see a value of both compasses, but #2 is ~100 more then #1, should i continue to calibrate the compass until it gets better?