What controls 'NavYaw'?

Hello everyone,

While trying to diagnose some minor oscillations in my Quads Yaw I decided to follow the Wiki page to check for compass interference (copter.ardupilot.com/wiki/common … terference).

Looking at the log of a short test flight I made, I noticed something I don’t really understand and hope someone can explain. In the log I can see my wobbly ‘YawIn’ input, and then see a resulting change in the very stable ‘NavYaw’, along with a less stable and somewhat oscillating ‘Yaw’ output/result.

What I don’t understand is, at around point 2093, I see the ‘NavYaw’ change at a time when there is no ‘YawIn’ input from me. Why is this? All of this is happening in ‘Stabilize’ mode, so I assume the yaw should only change with input from me, correct?

Any explanation would be very welcome! The log is attached.



We also don’t let the nav yaw be more than 10 degrees from the actual yaw. So if some kind of disturbance kicks in that yanks the copters yaw around you’ll find that the nav yaw gets yanked around as well.

Hi, Thanks for your reply and insight, very interesting.

Looking at the logs more closely, I see that Yaw is actually leading NavYaw which I hadn’t noticed before, and the difference does seem to be 10 degrees.

The graph image is a little misleading, probably due to some smoothing algorithm employed in drawing the lines, but looking at the actual point values shows that at the time of interest the values of Yaw and NavYaw suddenly become exactly 10 degrees different during the change of heading, so it does seem that the quad moved due to some other influence and NavYaw followed exactly 10 degrees behind.

Thanks for helping me understand this! :smiley: