尾座式垂直起降无人机过渡轨迹优化方法

Most transition trajectories obtained by traditional optimization methods are not feasible in the actual flight process. Moreover, the robustness of these transition trajectories is poor due to not considering the retention of sufficient actuator margin. In order to solve this problem, a transition corridor-based transition method for tail-sitter unmanned aerial vehicle (UAV) is proposed. Considering a type of dual-rotor tail-sitter UAV, a nonlinear dynamic model is constructed by distinguishing the aerodynamic characteristics of the wing in the propeller airflow region from those outside the region. Inspired by the research on transition corridors for tilt-rotor aircraft, a transition corridor is designed. The feasibility of the transition corridor is improved by limiting the range of climb rate and pitch angle rate. A trajectory located inside the transition corridor with the maximum safety margin is chosen as the target transition trajectory by the optimization method. Then, the transition process of the tail-sitter UAV is regarded as a trajectory optimization problem. By solving the trajectory optimization problem, the optimal transition trajectory which is closest to the target transition trajectory and retains sufficient actuator margin is obtained. Finally, based on the designed transition control framework, hardware-in-the-loop simulation experiments and real flight tests are conducted. Simulation results are consistent with the real flight results, which prove that the designed transition method can guide the aircraft to complete the transition quickly and safely while retaining a certain actuator margin, avoiding such unfavorable conditions for the transition flight as excessive altitude increase, long transition time and actuator saturation.