【作者】 蔡鹏；

【导师】 王庆超；

【作者基本信息】 哈尔滨工业大学 ， 一般力学与力学基础， 2008， 博士

【摘要】 随着航天技术的发展,越来越多的航天器上开始使用大型挠性结构,如大尺度挠性天线、太阳帆板和大型空间桁架等。在轨运行的挠性航天器的刚体运动将激发柔性附件的弹性变形运动,且两种运动相互耦合,导致航天器的刚柔耦合动力学行为非常复杂。因此研究挠性航天器的动力学模型并设计其姿态控制系统具有重要的意义。本文结合航天科技集团“十五”基础预研项目“复杂机构卫星智能自适应逆控制技术的研究”和国家自然科学基金“一类复杂系统中无源化近似自适应逆控制研究”,以含柔性关节的挠性航天器为对象,对此类航天器的建模、姿态控制及附件振动抑制等问题展开了深入的研究,其研究内容主要包括以下几个方面:一、在分析刚体模型和固支悬臂梁附件航天器模型的基础上,利用拉格朗日动力学方程建立了柔性关节链接悬臂梁附件的挠性航天器动力学模型。并采用假设模态–混合坐标方法,推导了梁式附件的振动方程,将挠性航天器的耦合动力学方程规范化,使之适用于姿态控制系统的分析和设计。进一步的,本文建立了带多个悬臂梁式附件的挠性航天器和带链式多悬臂梁附件的挠性航天器动力学模型。最后简要的分析了航天器执行机构的特性,并根据对象模型设计了PWPF调制器的参数。二、目前被广泛应用的输出反馈姿态控制方法具有结构简单的优点。为了进一步抑制挠性航天器的低频振动,在传统输出反馈控制思想的基础上引入了输入成形方法,并根据输出跟踪控制模型设计了变结构控制器。将该控制器和传统的PD控制策略进行了对比仿真,结果表明所设计控制器的姿态控制精度具有明显的优势,达到了抑制了航天器本体机动所激发的附件振动的设计要求。三、设计了模态状态观测器,使用较少的传感器来估计附件振动的模态。在此基础上,根据最优输出跟踪理论和保性能控制理论,分析并设计了控制受限情况下的参数不确定系统的最优保性能反馈控制控制律。该控制律易通过求解线性矩阵不等式组及其极值优化问题得到,具有较高的控制精度和较好的鲁棒性。四、将智能压电结构应用到附件的主动振动抑制上,此时系统模型变成了多输入系统。首先研究了集中控制方法,在上一部分成果的基础上设计了控制受限的多输入系统的最优保性能反馈控制控制律。其次按照分散控制的局部状态反馈设计思想,设计了状态观测器和局部状态反馈控制律。仿真结果表明两种方法都可以达到姿态控制精度要求并有效的抑制柔性附件的振动。最后根据仿真结果横向的比较了三类四种控制器的控制精度,系统鲁棒性,工程应用价值和局限性。更多还原

【Abstract】 With the development of aerospace techniques, more and more large scale spacecrafts adopt flexible structure, e.g. large scale flexible antenna, solar array and large space etc. Rigid body motion of flexible spacecraft in orbit will excite elastic deformation of flexible body, and these two kinds of motion are coupled and affected by each other which results in the significant complexity of rigid-flexible coupling. Hence, research on dynamic model of flexible spacecraft and designing its attitude control system has important significance. Supported by CASC project“Complex framework satellite intelligent adaptive inverse control technique research”and NSFC project“Adaptive inverse control based on passivity approach and its application in a class of complex system”, we take the flexible spacecraft with cantilever beam where the beam appendage is connected with body through flexible joints as the research object in this thesis, and do a deep research on modeling of flexible spacecraft, attitude control and suppressing of appendage vibration in term of theory. It mainly consists of the following aspects:1. Dynamics model of flexible spacecraft with cantilever beam is derived using Lagrange Dynamics Equation after analyzing rigid model and model of spacecraft with clamped support cantilever beam appendage. Model analysis method is adopted and vibration equation of beam appendage is derived. Coupling dynamics equation of flexible spacecraft is normalized to adapt the analysis and design of attitude control system. Furthermore, models of flexible spacecraft with multiple cantilever beam appendage and multiple cantilever beam appendage with joints are derived. Finally, characteristic of spacecraft actuator is analyzed simply, and parameter of PWPF is designed.2. Attitude control methods of flexible spacecraft include output feedback, state feedback and decentralized control, in which the output feedback has the advantage of simple structure. The input shaping is introduced to suppress low frequency vibration of spacecraft based on the idea of traditional output feedback, and variable structure output feedback controller is designed using tracking control model. It was compared with the traditional PD control strategy. The simulation results indicated the presented method had the obvious advantage in suppress the low frequency vibration exited by maneuver of spacecraft body. At the same time, similarities and differences of attitude control requirement between this kind of spacecraft and generals is discussed based on the simulation results.3. State observer is designed to utilize less sensors on beam estimating vibration modes of appendage. By this way, the requirement of state feedback is approved. On the basis of this, optimal guaranteed cost feedback control law of uncertain parameter system is analyzed and designed when control is constrained. This control law has good robustness via solving LMI and extreme value optimization problem.4. Piezoelectric elements are used to suppress vibration which makes system model be a multi input system. At first, optimal guaranteed cost feedback control law of control constrained multi input system is studied, which is a centralized control method. Local state observer and decentralized feedback control law are designed based on the design idea of decentralized control for local state feedback. The simulation results indicate that both of these two methods can approve the attitude control precise requirement and suppressed the vibration of flexible appendage efficiently.更多还原