Strange,sudden uncommanded left yaw and motion during a flight...

[BudWalker]

Those are rate gyro degrees per second rather than degrees, and I think you are looking at noise and digitization effects. If you back out a little it looks better:

View attachment 67680

And if you integrate the rate gyro data to get degrees:

View attachment 67681

There are some differences, but they don't seem large enough to account for the 90° yaw error. Looking at the Z-axis gyro data specifically, the difference is only 11° when the yaw error is 88°.

View attachment 67683

IMU1 is active because the OSD_yaw value follows the IMU1 yaw, not IMU0 yaw:

View attachment 67684

Yeah, but... Too bad we don't have higher freq data. It looks to my uncalibrated eyes like there is an increase in the difference between the IMU(0):gyroZ and IMU(1):gyroZ. Kinda starts at 587 secs. The incorrect IMU(1):Yaw starts at 590 secs. Also, the integrated IMU(1):gyroZ is similar to IMU(1):Yaw indicating that it's not just noise. As you pointed out there is an 8:1 scale difference though - are you using the DatCon integrated values or do you have Igor do the integration?


If any of this has merit then a HW issue with IMU(1):gyroZ seems possible.

 

[BudWalker]

....... Maybe @BudWalker will be able to figure out what I must have missed.

It's not April 1 yet.

 

[sar104]

Yeah, but... Too bad we don't have higher freq data. It looks to my uncalibrated eyes like there is an increase in the difference between the IMU(0):gyroZ and IMU(1):gyroZ. Kinda starts at 587 secs. The incorrect IMU(1):Yaw starts at 590 secs. Also, the integrated IMU(1):gyroZ is similar to IMU(1):Yaw indicating that it's not just noise. As you pointed out there is an 8:1 scale difference though - are you using the DatCon integrated values or do you have Igor do the integration?
View attachment 67753

If any of this has merit then a HW issue with IMU(1):gyroZ seems possible.

I ran the integration in Igor, primarily to check for consistency with DatCon's totalGyroZ. The two z-axis gyros have slightly different drifts and so, since we are 600 seconds into the flight, you need to zero the integrals just before the data diverge (i,e. at around 580 seconds) in order to see the magnitude of the divergence. I just can't find 90° of discrepancy.

 

[gnirtS]

Someone queried launch/recovery technique. Same as always from the boat, hand launched from top deck holding it above the head and out over the side. Hand caught later. Technique that has worked 100s of times with a M1 and M2 combine.
Radar and all other emitters were switched off and verified as off.]

One odd thing with this incident is it seemed to self-fix and i was able to recover it after a minute or so of it going berserk. I received no warnings about IMUs or compass. I suspect the high wind warning was the system thinking it was windy when in fact it was the IMU going haywire.

Between that and all my batteries swelling severely now i dont trust it as much as id like for flights over water.

 

[ff22]

Someone queried launch/recovery technique. Same as always from the boat, hand launched from top deck holding it above the head and out over the side. Hand caught later. Technique that has worked 100s of times with a M1 and M2 combine.
Radar and all other emitters were switched off and verified as off.]

One odd thing with this incident is it seemed to self-fix and i was able to recover it after a minute or so of it going berserk. I received no warnings about IMUs or compass. I suspect the high wind warning was the system thinking it was windy when in fact it was the IMU going haywire.

Between that and all my batteries swelling severely now i dont trust it as much as id like for flights over water.

Hmmm, I'd like to hear more about that! Are you using the DJI standard charger? Or 3rd party charger? Do you wait for them to cool a bit before recharging? Any other charging info you might have?

Good luck with future flights.

 

[gnirtS]

Hmmm, I'd like to hear more about that! Are you using the DJI standard charger? Or 3rd party charger? Do you wait for them to cool a bit before recharging? Any other charging info you might have?

Good luck with future flights.

Standard charger (Fly more kit) and batteries.
I think they just dislike heat (i live in the tropics). After flights with a lot of hovering or slow movement (hyperlapse etc) they started to swell pretty early on.
Now all 3 lock in but a tiny bump unlocks one side.

My Mavic 1 batteries did the same albeit took a lot longer to do so.

 

[ff22]

Standard charger (Fly more kit) and batteries.
I think they just dislike heat (i live in the tropics). After flights with a lot of hovering or slow movement (hyperlapse etc) they started to swell pretty early on.
Now all 3 lock in but a tiny bump unlocks one side.

My Mavic 1 batteries did the same albeit took a lot longer to do so.

That does not sound good. I would presume that the batteries should be able to take a bit of punishment in warmer climes and not react with swelling. Sounds like poor design or is it impossible to design such batteries to perform well in warm climates???