不规则小行星探测器制导与控制方法研究

发布时间：2018-02-15 05:07

本文关键词： 软着陆落角约束视线角速率模糊参数优化　出处：《长春工业大学》2015年硕士论文　论文类型：学位论文

【摘要】：人类进一步了解太阳系及宇宙的主要途径是通过深空探测,也为今后考察、勘探和定居太阳系奠定基础。一般将深空探测分为三类：月球探测、行星探测和星际探测。本文主要研究小行星探测器着陆过程的制导与控制。首先,研究探测器的动力学方程。考虑到小行星形状不规则的特点,根据球谐系数与引力势能之间的关系,通过求解超定线性方程组得到小行星引力场的各阶次球谐系数。文中假定小行星以均匀的角速度自转,探测器在受到小行星弱引力场作用的同时,也考虑了太阳光压和其他星体引力摄动的影响。其次,针对小行星自身形状不规则、尺寸小、引力较弱,且探测器在接近小行星过程中会受到太阳光压和第三体引力摄动的影响,本文设计一种针对落角约束的最优滑模制导控制律。最优滑模制导控制律采用最优比例制导律与滑模变结构理论相结合,对速度大小和方向进行控制。该方法能够在系统受到太阳光压和第三体引力摄动的情况下,保证视线角速率趋于零,消除视线角速率的稳态震荡。通过MATLAB仿真验证可知,本文设计的最优滑模制导控制律,在考虑着陆过程中探测器的燃料消耗、小行星受到引力摄动的情况下,能够实现视线角速率逐渐接近零。最后,为了实现探测器的安全软着陆,本文选用了三次多项式的标称轨迹制导法来设计期望轨迹。设计出基于模糊参数优化的滑模变结构控制方法,采用模糊参数优化策略动态调整切换增益,实现在滑模面外时加快响应速度并增强系统克服太阳光压和第三体引力摄动,到达滑模面时柔化控制量以消除抖振的目的。通过MATLAB仿真验证可知,本文设计的模糊参数优化滑模变结构控制方法可以有效提高系统的稳定性,保证趋近运动快速性并有效的消除抖振,同时避免了传统指数趋近律切换面附近控制力频繁切换的缺点。
[Abstract]:The main way for mankind to learn more about the solar system and the universe is through deep space exploration, as well as by laying the foundation for future exploration, exploration and settlement of the solar system. In general, deep space exploration is divided into three categories: lunar exploration, Planetary exploration and interstellar exploration. In this paper, the guidance and control of asteroid probe landing process are studied. Firstly, the dynamic equations of the asteroid are studied. According to the relation between spherical harmonic coefficient and gravitational potential energy, the spherical harmonic coefficients of every order of asteroid gravitational field are obtained by solving overdetermined linear equations. The probe is affected by the weak gravitational field of the asteroid, but also takes into account the influence of the solar pressure and the gravitational perturbation of other stars. Secondly, the asteroid itself is irregular in shape, small in size and weak in gravity. And the probe will be affected by the solar pressure and the third body gravitational perturbation in approaching the asteroid. In this paper, an optimal sliding mode guidance control law for angle constraints is designed. The optimal sliding mode guidance law combines the optimal proportional guidance law with the sliding mode variable structure theory. The magnitude and direction of the velocity are controlled. The method can ensure the angular velocity of line of sight tends to zero and eliminate the steady state oscillation of the angular rate of sight when the system is subjected to the solar pressure and the third body gravity perturbation. The optimal sliding mode guidance control law designed in this paper, considering the fuel consumption of the detector and the gravitational perturbation of the asteroid during landing, can achieve the line of sight angular rate approaching zero gradually. In order to realize the safe soft landing of the detector, the cubic polynomial nominal trajectory guidance method is used to design the desired trajectory, and the sliding mode variable structure control method based on fuzzy parameter optimization is designed. The fuzzy parameter optimization strategy is used to dynamically adjust the switching gain to accelerate the response speed and to enhance the system to overcome the solar pressure and the third body gravity perturbation when the sliding mode is off-plane. In order to eliminate buffeting, the fuzzy parameter optimization sliding mode variable structure control method designed in this paper can effectively improve the stability of the system. It can guarantee the rapidity of approach motion and eliminate buffeting effectively, while avoiding the disadvantage of frequent switching of control force near the traditional exponential approach law.
【学位授予单位】：长春工业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：V448.2

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