An euler angle calculation method for tailsitter UAV

The tailsitter UAV has very broad application prospects. However, it needs to switch between flat and vertical flights, so the pitch angle will exceed 90°. Unfortunately, the traditional Euler angle calculation method is not only singular (gimbal lock) but is also not compatible with the navigation calculations in the two flight modes. Therefore, a new Euler angle calculation method for a UAV is proposed. This method only avoids the singularity in the flight mode switching, but is also compatible with the navigation calculations in the two flight modes.