We did a XAUV Talon flight with latest Arduplane release.
The flight started fine in auto take off with a catapult method.
Once in flight the plane started to make a sinusoidal trajectory as if the center of gravity was off, although the CG had been perfectly tuned before take-off. For that part, I suspect the battery moved during the catapult launch, so that is easily explained (we also see clearly in the log a difference between desired pitch and pitch).
What is more strange and something I can't explain is that , once flipped into auto mode, the plane started to loose altitude from 70m to 40m (between line 550 and 580) when the waypoint should have brought it to 100m high ! (see picture below).
The plane was immediately flipped back to FBWA to increase "manually" its altitude back up (from line 580).
After a few moments, still in FBWA the plane starts to climb alone without any reason (pitch remains flat near zero), as shown in picture (from line 640):
- First question : What can cause the plane to loose altitude in auto mode when it should climb ?and reversely why does it start climbing in FBWA with no pitch commanding to go up ? Could it be a CG balance problem putting the nose up ? Strong winds ? Bad parameters ?
Then mission planner displayed these EKF errors that I do not know how to interpret,
- Second question : what mean these EKF errors ? (see picture)
Error pos horiz variance
Error velocity variance
Thanks for helping understand what went (or is) wrong with the altitude weird behaviour (question 1) and interpretation of the EKF errors (question 2),