Hi,
I’m sorry but I was wrong. So for whoever reads this:
Ardupilot uses NED (North - East - Down) frame of reference. See this:
pixhawk.org/dev/know-how/frames_of_reference
Copy pasted what’s important:
NED Coordinate System:
- The x axis is aligned with the vector to the north pole (tangent to meridians).
- The y axis points to the east side (tangent to parallels)
- The z axis points to the center of the earth
There is also Body Fixed Frame:
Body Fixed Frame (Attached to the aircraft)
- The x axis points in forward (defined by geometry and not by movement) direction. (= roll axis)
- The y axis points to the right (geometrically) (= pitch axis)
- The z axis points downwards (geometrically) (= yaw axis)
In order to convert from Body Frame to NED what you need to call this function:
copter.rotate_body_frame_to_NE(vel_vector.x, vel_vector.y);
Cheers
Nitay