Nonlinear control of maneuvering fixed wing UAVs using quaternion logarithm

The paper deals with the orientation and position control of maneuvering fixed wing UAVs. The nonlinear dynamic model of the aircraft can take into consideration slowly varying wind effects. A damping component in the nonlinear model supports the stability. An attitude control method was developed using quaternion logarithm in the body frame. A reference signal design method was elaborated for UAVs that can smoothly connect straight line, circle arc and twist sections for maneuvers. The path satisfies continuous acceleration to decrease saturation in the actuators. For orientation and position control the fusion of backstepping control (BSC) and dynamic inversion was applied. The simulation experiments for testing the algorithms show acceptable precision.