Least global position information based control of fixed-wing UAVs formation flight: Flight tests and experimental validation

The paper addresses the design of an innovative navigation and control method for the flight control of a formation consisting of small and low-cost fixed-wing UAVs by using a leader-follower strategy and a least global position information sharing algorithm. No additional hardware is needed except the classical global positioning system and autopilot. The novel strategy firstly involves the obtaining of the relative kinematics for the formation of UAVs by using a trajectory coordinate system and a navigation algorithm based on global position coordinates. Secondly, the flight control laws for each UAV are designed by means of the Active Disturbance Rejection Control, the convergence and robustness are discussed and proved, while the flight control laws for the whole formation are derived within a PI controller which balances the robustness and the computation of the whole control architecture. Then, by considering the requirements of positioning accuracy in low-cost constrains, the control scheme is validated both by numerical simulations and experimental flight tests along a racetrack-shaped circular path. The results prove an excellent accuracy for the navigation and control method, the follower UAVs following the trajectory of the leader UAV no matter if the flight is straight or turning type.