Certainly not intentionally. Was literally the second time I have used DJI Assistant and all I can recall doing was setting it to grab the VM as well. But may have done so accidentally.
barely but main thing is you have actually got the offending bit..
YES I sent it to DJI support with a note to say I am not looking for any special support, simply...
" ..passing this info on in the hope that the included files may be of assistance to your engineers in assessing and fixing whatever is causing this problem. "
They replied " I have forward the details to the team. Hope the next firmware will fix it.".
First, let me describe what happened. Then, I'll guess at the reasons behind the incident.
The Yaw value is the Flight Controller's notion of the A/C heading (i.e. which way it's pointing). The red arrow you see in the Go App is the Yaw value. Sometimes the FC gets confused and it's notion of Yaw is incorrect. Yaw isn't just the compass magnetometer values. It's computed from several sources and depends very little on the magnetometer values. magYaw is a value computed by DatCon and derived from the magnetometer data with a correction for pitch and roll. magYaw is just a DatCon diagnostic; it's not an actual FC value. But, it is useful in situations where the Yaw value is suspect.
Normally, Yaw and magYaw track each other closely. There may be some variations as the FC has to continually correct it's Yaw prediction. But, usually they are close. When the Yaw/magYaw separation gets large (> 25 degrees) then there is a possibility that the Yaw value is incorrect and the FC then switches to ATTI mode. That's what happened in this incident.
The Yaw/magYaw separation had been about 11 degrees (the geoMagnetic declination at the launch site is 12 degrees). At about 46 secs the Yaw/magYaw separation began increasing and was at 37 degrees at time 162.5 when the FC switched to ATTI from NaviGo. The TBE had already started.
But then, why was there a Yaw/magYaw separation? I really don't know why this happened. I really should know better, but I'll make a guess.
@Logger you had made the point that this mission was identical to the two before it. But, what's different is the wind speed and direction. Since the FC has to correct for this these are actually different flights. But, still the FC should be able to reliably predict Yaw.
Again, this just a guess on my part that will probably be debunked or modified. The gyroZ error is about 5 times larger than what I've seen with the limited number Mavics for which I have a .DAT. totalGyroZ is a value computed by DatCon that integrates and then sums the gyroZ value. If the Mavic is stationary then any change in totalGyroZ is due to the gyroZ error. In this flight totalGyroZ changes 13 degrees in the 27 seconds before launch. That's 0.5 degrees/sec; about 5 times the usual 0.1 degrees/sec seen on the other Mavics I've looked at. The guess here is that this may have contributed to the Yaw/magYaw separation. This also the usual gyroZ error on the P3.
0.5 degrees/sec error is probably within spec. After all, the Mavic is probably smarter than a flight analyst wannabe and it didn't say an IMU calibration should be done. My P3 had 0.4 degrees/sec error until I calibrated the IMU. That error was then improved to 0.08 degrees/sec. You might want to try an IMU calibration and see if you get an improvement.
Still left unanswered with these incidents is why does the Mavic continue to navigate when it switches to ATTI mode. I'm supposing it should drift with the wind rather than trying to hover at the same spot.