Atti mode!!

[Bala]

Hi. I took my 1st flight of the season yesterday. Mavic had not flown for months. Did all the stuff on launch pad; waited for sats and made sure homepoint was recorded. Also made sure the app arrow was pointing the same direction as the mavic. All was good (or so i thought) and at take off i had 23 sats. Kept her close, it being the 1st flight in a while and glad i did! Flew perfectly for a while and then got a compass and imu warning. Went into atti mode for about 30 secs and caused a slight heart flutter! Had never done that before. The wind was around 5-10 mph so didn't drift much. The gps then came back and i decided to land. I'm gonna try and put flight log attached to this. Could anyone tell me what caused this please? Thanks. I'm sorry for putting 3 files on but was'nt sure which was the right one. I hope one of them is!??

 

[sar104]

Yaw was initialized okay, but there was a bit of a disagreement between the IMU and compass starting around 60 seconds that caused the IMU error. It was fully resolved at around 100 seconds:



63.000 : 15600 [L-FDI]ns req:fdi,0to0,reason:fusion.gps_yaw_err,result:fail for same index
64.184 : 15659 [L-FLYMODE][Ctrl<1>] REQ_RC_NORMAL ATTI ctrl_atti
91.462 : 17023 [L-FLYMODE][Ctrl<1>] REQ_RC_NORMAL ATTI_HOLD ctrl_gps_atti
100.592 : 17479 [L-NS][AHRS] yaw aligned 1

There is some evidence of FC rotation during the flight - you might want to do a compass calibration and recheck.

 

[Bala]

Thank you @sar104 . I'll do the compass calibration. Do you recommend an imu calibration as well?? Could you also explain how to check for fc rotation? Not sure what that means. Is there any hint in the logs as to why it happened?

 

[sar104]

Thank you @sar104 . I'll do the compass calibration. Do you recommend an imu calibration as well?? Could you also explain how to check for fc rotation? Not sure what that means. Is there any hint in the logs as to why it happened?

No harm calibrating the IMU. I don't know what is causing the rotation but, since the aircraft seems to have a tendency to slowly rotate CW, it could be an issue with one of the rate gyros. You can see the rotation in the blue compass trace in the graph above - there are several periods during which it gradually drifts.

 

[Bala]

Many thanks for doing that @sar104. I have calibrated the compass, imu and controller. Will put it in a low hover tomorrow and see if rotation is fixed/better. I'll report back if that's ok. I often see the good work you do on here and am in awe of the way you help folk. I, like them all, am grateful.

 

[Bala]

Flew my mavic last night. I hovered it at about 10m beside launching point. Extremely slight rotation which i could see on screen and observing the drone visually. I sent it out further and flew a fair distance around the area back and forth. Took the battery down to 40%. I then hovered before landing. The rotating seemed to have disappeared. So, all in all, a successful flight with no worries. I'll keep an eye on the rotating and look into it further if it appears again.