月球探测器精确软着陆制导算法研究

哈尔滨工业大学工程硕士学位论文

Abstract

Soft landing on the lunar surface is an indispensable part in lunar probing plan. And moreover, navigation, guidance and control are the key techniques for lunar soft landing. With the support of Research Center for Deep Space Exploration, Harbin Institute of Technology, "The Study of Lunar Soft Landing High Precision Navigation and Guidance Methods", this dissertation systematically studies guidance problems in the lunar landing procedure employing optimal control, optimization, nonlinear control methods based on precursors’ results.

To solve the guidance problem of unfixed point soft landing, a fuel-optimal guidance law is developed by Pontryagin maximum principle of the classic optimal control theory. Then, it is proved that the singularity condition that causes control function uncertain can not hold along an optimal trajectory on any closed time interval. In the end, by using nonlinear programming in order to obtain the numerical solution for the optimal trajectory, the two-point boundary value problem is be solved.

To solve guidance problems of pinpoint soft landing, a piece-wise constant parametric guidance law is designed by the method of parametric control and control variable parameterization, firstly an optimal open-loop guidance law is designed to obtain the optimal trajectory of powered descent phase of soft landing by using optimal control and optimal parameter selection, and then a nominal trajectory guidance method is developed to track the optimal trajectory. Then, the optimal control problem can be transformed into a parameter optimization problem by this method. Hence, the optimal parameters can be solved by the common mathematic programming, and the approximating precision can be enhanced by increasing the number of parameters until an acceptable solution is derived.

Keywords:nonlinear programming; control variable parameterization; optimal control; variable time nudes

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哈尔滨工业大学工程硕士学位论文

摘要 .................................................................................................................... II Abstract ................................................................................................................. I II 第1章绪论 .. (1)

1.1课题来源与研究目的及意义 (1)

1.1.1 课题来源 (1)

1.1.2 课题研究目的及意义 (1)

1.2国内外研究现状 (2)

1.2.1国外月球探测发展历程 (3)

1.2.2国内月球探测研究现状 (5)

1.2.3月球探测器软着陆制导方法研究现状 (7)

1.3本论文研究内容与结构 (9)

第2章月球探测器软着陆过程分析与动力学建模 (11)

2.1引言 (11)

2.2月球探测器软着陆过程分析 (11)

2.2.1月球软着陆阶段划分 (11)

2.2.2月球探测器软着陆轨道约束 (12)

2.2.3月球探测器软着陆着陆点选取 (13)

2.3月球探测器软着陆过程方案设计 (15)

2.4月球探测器软着陆动力学建模 (17)

2.4.1极坐标系下软着陆二维动力学建模 (17)

2.4.2 直角坐标系下软着陆三维动力学建模 (18)

2.5 最优控制理论 (22)

2.6本章小结 (23)

第3章基于非线性规划的月球软着陆制导律设计 (24)

3.1 引言 (24)

3.2 月球探测器软着陆燃料最优制导律设计 (24)

3.2.1 非线性规划方法 (24)

3.2.2 燃料最优制导律设计 (25)

3.3 燃料最优制导律奇异过程分析 (28)

3.4 非线性规划解两点边值问题 (29)

3.4.1 两点边值问题描述 (29)

3.4.2 初值猜测技术 (30)

3.5 仿真实验与分析 (32)

3.6本章小结 (33)

第4章基于参数化的月球精确软着陆制导律设计 (34)

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哈尔滨工业大学工程硕士学位论文

4.1 引言 (34)

4.2 控制变量参数化 (34)

4.3 终值时间不固定最优控制问题转化 (40)

4.3.1 时间转换法 (41)

4.3.2 变时间节点法 (42)

4.4 动力下降段制导律设计 (46)

4.5 仿真实验与分析 (50)

4.6 本章小结 (52)

结论 (53)

参考文献 (54)

攻读学位期间发表的学术论文 (60)

哈尔滨工业大学学位论文原创性声明和使用权限 (61)

致谢 (62)

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