针对混合动力复合翼飞行器巡航模式下空中停车后无动力应急迫降问题，提出在线航迹规划与制导方法。根据复合翼空中停车时初始位置/航向不确定问题，发展一套满足动力学约束、终端约束的三维航迹在线规划方法：利用几何规划方法快速生成扩展Dubins二维航迹，再根据下滑性能约束进行三维扩展。针对低速无动力下滑航迹跟踪更易受风干扰以及三维航线分段连接处曲率不连续的特性，发展一种基于非线性模型预测控制的三维制导算法。将纵横解耦的制导律嵌入到预测模型框架内，跟踪误差、外界风扰动、航迹曲率不连续等非线性因素则通过系统输出建立目标约束，其后利用滚动优化实时求解制导指令。最后对航迹在线规划方法与三维制导律的适用性进行仿真分析与验证，结果表明所提出的航迹规划方法适用于不确定初始位置/航向散布的应急迫降在线规划，所提的制导算法具备抵抗风扰、提高三维制导精度的能力。
An online path planning and a guidance law method are proposed for the unpowered forced landing problem of the hybrid vertical take-off and landing (VTOL) unmanned aerial vehicles(UAVs). According to the casual initial location and heading when the UAV losses power, a three-dimensional path planning method that satisfies both dynamic and terminal constraints is developed. Using the geometric planning method to design the extended Dubins plane path, three-dimensional curves are generated based on the gliding stability and performance. Since the unpowered path following is susceptible to wind disturbances in low speed and the curvature of planed curves is discontinuous, a three-dimensional guidance algorithm based on nonlinear model predictive control is proposed. Combined with the lateral-longitudinal decoupled guidance dynamic, nonlinear factors such as following error, external wind disturbance and path curvature discontinuity are modeled as the system output constraints, and guide commands are rolling solved in real time. Finally, the validation of the online path planning method and the guidance law are simulated and verified. The simulation results show that the proposed online planning method is suitable for the emergency landing from casual locations and headings, and the proposed guidance algorithm has the capability to resist wind disturbance and follow the three-dimensional path accurately.
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