带挠性太阳帆板的三轴稳定卫星姿态控制系统分析与设计研究

【作者】 刘镠；

【导师】 周伯昭；

【作者基本信息】 中国人民解放军国防科学技术大学 ， 航空宇航科学与技术， 2002， 硕士

【摘要】 论文以带挠性太阳帆板的三轴稳定卫星为研究对象，目的是将近期发展起来的H_∞鲁棒控制理论应用于卫星的姿态控制，使其姿态满足定向精度要求。论文的另一目的是挠性卫星姿态控制方案研究。 作者首先建立了三轴稳定刚体卫星姿态动力学模型，并引入考虑了太阳帆板弹性的挠性卫星姿态动力学模型，然后用经典PD控制和线性二次型最优控制方法分别为刚体卫星的俯仰通道和滚动偏航耦合通道设计了控制律，并作了一定的仿真分析，这为检验后来求得的H_∞鲁棒控制器控制效果奠定了基础。接着，在假定系统中存在诸多不确定性的情况下，设计了刚体卫星H_∞鲁棒控制器。由于鲁棒控制器求取算法复杂，H_∞广义控制对象满足一定前提条件时才有解，加权函数的选取又无标准可依，很大程度上依赖于设计者的实践经验，所以论文采用了扩展系统方法。这种方法易于理解和掌握，它克服了通过选择加权函数使广义控制对象满足条件的抽象性和经验性。它在多变量系统中更显优势。接着作者对经典控制(相对于鲁棒控制而言)和H_∞鲁棒控制的控制效果进行了对比分析，所得结论是求得的H_∞控制器较经典控制律在抑制外部干扰方面有明显优势。它能很好地克服外部常值干扰力矩，不仅使系统姿态较快趋于稳定且使姿态回复到原指向，而PD和线性二次型最优控制虽然能使系统姿态稳定但却使其稳定在新的方向上。 不过需要指出的是控制系统的稳定性和性能与系统中存在的不确定性之间存在着矛盾。从仿真结果看，鲁棒控制器满足了系统的鲁棒稳定性但对系统的动态特性却有所削弱。另外，求得的控制器阶数偏高，这是H_∞控制理论存在的普遍问题，还有待进一步研究。 对于挠性卫星，作者研究了帆板反对称弯曲振动对卫星姿态的影响。仿真结果表明在原刚体控制律下，太阳帆板振动使卫星的控制力矩和姿态角产生严重超调和振荡。针对这种情况，作者运用经典PD控制加滤波器方法重新设计了控制器。仿真结果表明，相对于经典PD控制方法，此方法使卫星的由于太阳帆板弹性振动引起的姿态严重超调和振荡有所减小。接着，作者通过选取加权灵敏度函数设计了挠性卫星鲁棒控制器。仿真结果表明，此鲁棒控制器控制效果优于经典PD控制，其前提条件是选择恰当的权函数，但权函数选取不是很容易，它在很大程度上依赖于设计者的实践经验。最后作者还简要分析了加权灵敏度函数的参数选取对系统动态性能的影响。 论文分为两大部分： 1、H_∞控制理论及其在三轴稳定卫星姿态控制中的应用研究； 2、挠性卫星动力学模型分析及其控制方案研究。更多还原

【Abstract】 The paper deals with three-axe stabilized satellite with flexible solar arrays. The main objective is to apply robust control method to attitude control of three-axe stabilized satellite. In addition, the study of how to suppress attitude vibration caused by flexible solar arrays is another aim.Initially, the rigid body dynamics of three-axe stabilized satellite and flexure dynamics are introduced. The classical PD control law and Linear Quadratic Regulator then are respectively designed to stabilize rigid body attitudes. In order to compare control effect with subsequently obtained H∞ robust control law, there gives acertain degree of simulation analyses of the classical control law. Under a good many of supposed uncertainties and exterior disturbs, H∞ robust control laws to pitch axe and coupled roll and yaw axes are respectivelyobtained. Because arithmetic of H∞ robust control law is very difficult, control law will be obtained only when control object meet some premises, and it is also very difficult to choose appropriate weighting functions, there use a way in the paper to meet all those premises through enlarging control object. In comparison with choosing weighting functions, the way steers clear of abstraction and experience. Its metric can be especially embodied in multivariate control system. At last, there gives an overall comparison between classical control law and robust control method. The conclusion is that the H∞ robust control law are more superior in overcoming influence ofuncertainties especially exterior disturbs exist in control system to classical control law.It should be pointed out that uncertainties exist in control system stand in contradiction with system’s stability and performance, though the H∞ robust control laws meet the need of robust stability , it weaken the system’s dynamic performance. In addition, the orders of H∞ robust control laws are universally high, it need to be further studied.To flexible satellite, the paper lays stress on analyzing influence of solar arrays’ anti-symmetry bend on satellite attitude. The simulation results are that under body control law, the flexible solar arrays cause serious vibration and overshoot of attitude. In order to weaken the vibration and overshoot, classical PD control in company with filter is applied. The method can diminish attitudes vibration and overshoot to a certain degree. In addition, there designed robust control law in the paper to flexible satellite through choosing weighting sensitivity function. Simulation effects indicate that robust control law is superior to classical control law preconditioned appropriate weighting functions must be chosen. But its control effect is not better than that of PD control law with filter. At last, there gives simple analyses about why weighting sensitivity function was modeled like that.There are two parts mainly involved in the paper:1. H∞ control theory and its application in attitude control of three-axe stabilized satellite;2. Analysis of flexure dynamics and study of its control method.更多还原