摘要
考虑具有终端约束和过程约束的探月返回飞行器再入轨迹设计问题,通过将性能指标泛函定义为再入终端位置误差的平方和,再入轨迹设计问题转化为具有过程约束和状态方程约束的优化问题.首先仅考虑状态方程约束,利用最大值原理,得到该优化问题的必要条件,选取间接法中的共轭梯度算法求解最优控制量.进而针对轨迹约束问题,研究了再入过载和轨道飞行段飞行距离与航迹角以及倾侧角的关系,在此基础上,提出了采用调整初始倾侧角序列的方法实现过程约束.该算法克服了罚函数方法中需要调节参数较多的问题,并且物理意义明确,实现简单.最后,给出了Apollo再入轨迹优化的数值仿真算例,验证了所给出算法的有效性.
The reentry trajectory optimization problem with terminal constraints and path constraints of a lunar return vehicle is considered in this paper.By defining the performance index function as a square sum of the reentry terminal position errors,the reentry trajectory design problem is transformed into the optimization problem with terminal constraints and state equation constraints.First,in the presence of the state equation constraints only,the necessary conditions of the optimization problem are obtained by using the maximum principle,and the optimal control is solved using the conjugate gradient method.Then,in the presence of path constraints,we have studied the relationship among the overload,the distance of the orbit phase,the flight path angle and the bank angle.Based on the above,a method of initial bank angle value adjustment is presented to satisfy the path constraints.This approach,with definite physical meaning and simple implementation,circumvents the shortcoming of the punishment-function method which involves too many adjusted parameters.Finally,a numerical example for Apollo reentry trajectory optimization is given to illustrate the effectiveness of the algorithm.
出处
《空间控制技术与应用》
2012年第6期6-12,共7页
Aerospace Control and Application
基金
国家自然科学基金资助项目(61273153,60736023,60704014)
关键词
探月返回
跳跃式再入
轨迹优化
再入动力学的性质
初值调整
lunar return
skip reentry
trajectory optimization
property of reentry dynamics
initial value adjustment
