针对UCAV对地攻击轨迹规划问题，提出一种基于Radau伪谱法(RPM)的求解策略。首先，构建了最优控制问题的一般框架，分析了RPM求解最优控制问题的基本原理及实现方式；在充分考虑UCAV的气动力特性、发动机推力特性及大气环境特性的基础上建立了UCAV三自由度(3-DOF)质点模型，并详细分析了UCAV初始和终端位置、速度、姿态约束、飞行性能和战场环境等约束条件，在此基础上构建UCAV对地攻击轨迹规划问题框架；最后，利用RPM将轨迹规划的最优控制问题转化为非线性规划问题并求得最优解。仿真结果表明，该方法能以较高的精度和速度生成满足各种复杂约束要求、连续并且真实可行的最优轨迹。

This paper presents a strategy to deal with the issue of air-to-ground trajectory planning for Unmanned Combat Aerial Vehicle(UCAV) using a Radau Pseudo-spectral Method(RPM).First，the general frame of the optimal control problems was constructed，and the basic principle and implementation mode of RPM in solving the optimal control problems were analyzed.Secondly，a 3-DOF UCAV model was built up by taking the UCAV aerodynamic characteristics，thrust characteristics and the atmosphere environments characteristics into consideration.Various complicated constraints such as the preliminary and terminal position，speed and attitude constraints，flying performance and battlefield environment and so on，were analyzed in detail.Then，a frame of air-to-ground trajectory planning for UCAV was built up.Finally，the optimal control problem for trajectory planning was transformed into a nonlinear planning problem，and the optimal solution was obtained.Simulation results shows that the RPM can generate a continuous，viable and optimal trajectory satisfying various complicated constraints.