Compass error after yawing 360deg

[whatsman]

Hello everyone,

I bought Mavic Pro a week ago and didn't have a single successful flight yet. I keep getting "Compass Error. Exit P-GPS mode..." error. Both compasses are working and are calibrated in an open field. (tested by putting metal thing to compasses - both react as they should). I believe IMU calibration is good too. I did sensor calibration on DJI assistant 2 as well as the remote controller calibration on the app.

Here's the thing. I had some minor "crashes" when the drone takes off to 1 meter and starts spinning itself, then I land it immediately. I've started investigating what can cause this by reading this forum, and most of the time it is "bad location". so I tried flying it in different locations and sometimes I can get off the ground pretty ok, but today I understood one thing - when I yaw the drone 360deg (doesn't matter direction) the controller instantly gives me an error "Compass error. Exit P-GPS mode"... and the drone starts to drift on its own. ( I still can control it, and after a few seconds of Atti mode error disappears )

Video: Dropbox - IMG_9810.TRIM.MOV
DAT file: Dropbox - FLY080.DAT

I've monitored compass interference levels before flight and during the flight - both are green and working well with a value not higher than 40.

I've tried doing compass calibrations in different locations but I still get "Compass error" as soon as the drone yaws. I've never get "calibration failed" error though. Sometimes when I'm doing Compass calibration I just spin the drone and it doesn't get to the next step of calibration. Like ever. So I cancel calibration and start again. I'm sure that I do the calibration the right way (watched tons of youtube videos how to do it)

Also I've noticed that the drone sometimes is slightly yawing CCW on his own.

Any clue what can cause this issue? Maybe my drone was shipped together with magnetic stuff like speakers and those magnets misbalanced the compass? Now I am afraid to fly it more than 50 meters away from me.

Any help is appreciated.

 

[sar104]

At first glance - that looks like an IMU problem. The compasses agree well with each other, but disagree with the rate gyros - hence the error on yaw. Are you sure the IMU calibration is good? Have you calibrated it?

 

[whatsman]

At first glance - that looks like an IMU problem. The compasses agree well with each other, but disagree with the rate gyros - hence the error on yaw. Are you sure the IMU calibration is good? Have you calibrated it?

Thanks for taking a look at my issue.

Well I believe IMU is OK. I calibrated it a few times on level surface - each time after enormous behaviour of my drone. Also the values of gyroscope and accelerometer seems ok in DJI go app.
You think it is possible that the error I get says "Compass error" but it is IMU error?

This error stays on this screen during all my flights. I mean when I power on the drone - I don't see this error here, but once I move AC by hand or try to take off - I instantly get this error here and it stays on screen unless I restart the drone.

 

[sar104]

Thanks for taking a look at my issue.

Well I believe IMU is OK. I calibrated it a few times on level surface - each time after enormous behaviour of my drone. Also the values of gyroscope and accelerometer seems ok in DJI go app.
You think it is possible that the error I get says "Compass error" but it is IMU error?

This error stays on this screen during all my flights. I mean when I power on the drone - I don't see this error here, but once I move AC by hand or try to take off - I instantly get this error here and it stays on screen unless I restart the drone.
View attachment 35506

The error is due to the divergence (seen in the graph above) of the magnetic yaw and the IMU yaw computed from the rate gyros. It is flagged as a compass error but that doesn't mean that it is necessarily the compass at fault - it's just a general yaw error. Compass 1 is actually the compass in use, but since the two compasses agree so closely it seems unlikely that the magnetic yaw is the problem. That just leaves the IMU yaw.

You can see that after the yaw maneuver and divergence, causing the error, the FC actually rotates the aircraft CCW while holding the IMU yaw value constant in an attempt to resolve the issue, but the error is too large to fix.

 

[whatsman]

The error is due to the divergence (seen in the graph above) of the magnetic yaw and the IMU yaw computed from the rate gyros. It is flagged as a compass error but that doesn't mean that it is necessarily the compass at fault - it's just a general yaw error. Compass 1 is actually the compass in use, but since the two compasses agree so closely it seems unlikely that the magnetic yaw is the problem. That just leaves the IMU yaw.

You can see that after the yaw maneuver and divergence, causing the error, the FC actually rotates the aircraft CCW while holding the IMU yaw value constant in an attempt to resolve the issue, but the error is too large to fix.

OK thanks a lot for the information. I’ll try to refresh the firmware and recalibrate IMU. Hope this will help

 

[incho]

I got the same problem!
i got my Mavic pro almost half a year! But last flights i always get some errors. I'm running latest update, i did compass calibration, IMU calibration!
Did not have any crash before!
I'm flying in open area 200-500m from me with good signal, good satellite no metal interference and then got those errors -

Weak GPS signal
Compass error, exit P-GPS mode
IMU encounters heading exception

It turns to ATTI mode, sometimes drone fly's away without control, all i can do press return to home! Or wait until i get back my signal back!
I'm scared of flying now.
It happens every flight now, in different places!
Does anybody can help what to do?

 

[whatsman]

The error is due to the divergence (seen in the graph above) of the magnetic yaw and the IMU yaw computed from the rate gyros. It is flagged as a compass error but that doesn't mean that it is necessarily the compass at fault - it's just a general yaw error. Compass 1 is actually the compass in use, but since the two compasses agree so closely it seems unlikely that the magnetic yaw is the problem. That just leaves the IMU yaw.

You can see that after the yaw maneuver and divergence, causing the error, the FC actually rotates the aircraft CCW while holding the IMU yaw value constant in an attempt to resolve the issue, but the error is too large to fix.

I've started fresh today, did firmware refresh and all calibrations at home, except compass - did it in an open field. Same problem happens. Don't I understand how to calibrate IMU?.. It is really strange.

 

[sar104]

I've started fresh today, did firmware refresh and all calibrations at home, except compass - did it in an open field. Same problem happens. Don't I understand how to calibrate IMU?.. It is really strange.

If you are following the detailed instructions for the IMU calibration and the problem persists then it looks like a hardware problem. You will need to send it back.

 

[Paul2660]

I got the same problem!
i got my Mavic pro almost half a year! But last flights i always get some errors. I'm running latest update, i did compass calibration, IMU calibration!
Did not have any crash before!
I'm flying in open area 200-500m from me with good signal, good satellite no metal interference and then got those errors -

Weak GPS signal
Compass error, exit P-GPS mode
IMU encounters heading exception

It turns to ATTI mode, sometimes drone fly's away without control, all i can do press return to home! Or wait until i get back my signal back!
I'm scared of flying now.
It happens every flight now, in different places!
Does anybody can help what to do?

I would be careful about ATTI mode and hitting RTH.

If you are in ATTI mode hitting RTH will be a disaster. In ATTI you are altitude mode only no GPS. This means the drone can’t find home anymore and will fly off.

If you were briefly in ATTI mode but the regained signal RTH is an option for sure. However it’s no true failsafe as the drone could lose GPS or compass again in RTH.

In ATTI you still should have stick control and video. The drone will no longer hover so when you release the sticks it will the drift with the prevailing wind.

Paul Caldwell