中文摘要：

针对飞行器动力故障迫降着陆问题,提出一种应急着陆域（ELR）和着陆轨迹设计方法.首先,提出了无动力应急着陆域的概念,即无动力条件下可实现成功着陆的着陆点范围,并分别应用最优控制方法和hp自适应伪谱法对着陆域进行设计和求解;采用理论分析与仿真验证相结合的方法分析应急着陆域的特点以及影响着陆域大小的主要因素,并据此得到求解应急着陆域的简单近似方法.然后,依据所求得的应急着陆域,选择合适位置作为预定着陆点,并应用最优控制方法设计对应的着陆轨迹.仿真结果表明：应急着陆域的建立、分析对快速选择预定着陆点具有重要参考价值;设计的应急着陆轨迹可引导无动力飞行器实现成功着陆.

英文摘要：

Against the background of forced landing of unpowered aircraft caused by engine failure,this paper presents a design of the emergency landing region （ELR） and landing trajectory.First,the concept of ELR is introduced as the set of landing points within which an unpowered aircraft can achieve a soft landing.ELR is modeled using the optimal control method and computed through the hp-adaptive pseudospectral method.The features of ELR and the key factors that influence it are analyzed by theoretical deduction combined with simulation,and a simple approximation method to calculate ELR is obtained accordingly.Then,an emergency landing site is selected according to ELR,and the corresponding landing trajectory is designed through the optimal control method.Simulation results demonstrate that the establishment and analysis of ELR have great reference value for selecting an emergency landing site quickly,and the designed landing trajectory can guide an unpowered aircraft to a safe landing.