Longitudinal Perching Trajectory Planning for a Fixed-Wing Unmanned Aerial Vehicle at High Angle of Attack Based on the Estimation of Region of Attraction

In this paper, a method for planning the perching trajectory of a fixed-wing unmanned aerial vehicle (UAV) based on the estimation of the region of attraction (ROA) is proposed, to expand the feasible domain of a UAV in the presence of aerodynamic performance degradation and landing-limited conditions with high angle of attack (AOA). According to the aerodynamic characteristics of the system, the perching process is first decomposed into flight and landing segments, and the corresponding flight dynamic model and structural dynamic model are established, based on the Lagrange function, while the continuity of the two models is proved. Then, the structural dynamic model is analyzed for asymptotic stability based on the ROA estimation results from the Lyapunov function. On this basis, a fixed-wing UAV perching trajectory planning strategy is proposed. This strategy enables the UAV to achieve stable perching with a reasonable flight trajectory, as it fully considers the flight dynamic constraints of the UAV and the structural dynamic constraints of the landing gear. Our simulation results show that flight trajectory planning considering the ROA can significantly increase the number of available trajectories for fixed-wing UAVs during high AOA perching, which also greatly enhances its flexibility in trajectory selection.