【作者】 李连军；

【导师】 戴金海；

【作者基本信息】 国防科学技术大学 ， 航空宇航科学与技术， 2006， 博士

【摘要】 航天器设计面临任务复杂度增加、设计周期缩短、研制经费受限等多重压力,传统的设计理念已不再适应经济发展和军事应用的需要。虚拟原型技术的迅速发展,为以“快、好、省”为核心的新的设计理念以及基于并行工程的新的设计方法提供了良好的技术基础。本文以构建支持航天器设计、研制的功能行为虚拟原型为研究目的,就相关的建模/仿真方法、实施框架、软件实现等进行了深入的研究。主要内容包括:针对涉及多能量领域交互作用的复杂物理系统建模需要,提出了一种扩展的多端口建模方法(Extended Multiport Approach,简称XMPA)。该方法将模块之间的交互作用区分为能量流交互和信号流交互,相应的交互界面分别称之为能量端口和信号端口,其中信号端口又区分为事件端口和连续信号端口。以此为基础,提出了一个物理系统虚拟原型的形式化定义,给出了物理系统虚拟原型的层次化模型。进一步,从基于虚拟原型仿真的实际需求出发,定义了物理系统虚拟原型的视图模型,每一个视图均对应于虚拟原型的一个实现。针对航天器混合动态行为特征建模的需要,提出一种新的混合自动机形式化模型,即多端口混合自动机(Multiport Hybrid Automata,简称MPHA)。该模型分别用事件动作和连续变量描述系统状态的离散跃变和连续动态特性,不同模块之间的事件交互通过事件端口实现,而连续交互作用则通过连续信号端口或能量端口实现。进而,定义了MPHA之间的连接运算。该模型可方便地描述系统或模块内部的混合动态特性,同时可描述系统与其环境之间的多种形式的交互作用以及系统的层次化结构。基于软件集成的思想,提出了一个支持多能量领域物理系统功能行为建模与仿真的软件环境实现框架。该框架以Modelica语言和其应用环境Dymola以及Matlab/Simulink为底层建模工具,采用DCOM技术支持分布式仿真。为更好地支持多端口混合自动机建模,论文对Modelica库进行了扩展,以Modelica语言定义了事件端口和三维机械连接端口;给出了一条将Simulink模型快速转换为DCOM组件的技术途径。作为应用实例,基于扩展多端口建模方法,研究并实现了一种航天器姿态控制系统功能行为虚拟原型。该虚拟原型包括如下四个组件:结构与机构分系统组件、姿态确定与控制分系统组件、C&DH组件和本地环境组件,组件之间通过端口连接。每个组件都封装了若干数学模型,包括太阳光压力矩模型及考虑动量轮轴承摩擦、飞轮质量分布不均匀、飞轮弹性变形等因素的动量轮系统动力学模型,等等。运用Modelica语言建立了航天器系统的层次化功能结构模型,并定义了各级系统的MPHA模型;进而,综合运用Dymola和Simulink环境,将上述四个组件分别封装为DCOM组件,并将这些DCOM组件组装为一个航天器姿态控制系统功能行为虚拟原型;利用此虚拟原型,分别针对太阳光压力矩、动量轮系统内干扰、飞轮低速摩擦特性补偿、飞轮角动量之磁卸载及控制器切换等进行了仿真实验,验证了模型和虚拟原型建模方法的正确性、有效性。实现了一个支持航天器姿态确定与控制分系统设计、分析的虚拟原型环境。该环境由相对独立的两部分组成,即建模仿真环境与航天器运行可视化环境。建模仿真环境在模块库支持下工作,每个模块均封装为组件,并以Simulink模块和DCOM组件两种形式存在。用户可方便地对模块库进行管理,如添加新模型、对原有模型进行修改或升级等。软件支持两种运行方式:基于Matlab引擎的单机运行和基于DCOM组件的分布式运行。用户通过选择各种不同的功能部件或方法,并设置、修改相关的参数,得到一个一致的ADCS方案,进而对其运行状况进行仿真分析。航天器运行可视化环境基于Win32多线程机制构建,在外部仿真程序生成之数据的驱动下,以在线或离线方式演示航天器的轨道和(或)姿态运动,以及不同有效载荷的实时对地观测范围。其中涉及的实体模型运用OpenGL和MultiGen Creator建立;同外部仿真程序之间的通信通过SOCKET接口实现。该可视化环境已成功应用于多卫星系统仿真和航天器姿态运动仿真。上述研究成果为建立航天器功能行为虚拟原型奠定了方法论基础,为基于系统集成的实现技术探索了一条可行途径,对完全建立和实现航天器功能行为虚拟原型具有重要的指导意义和参考价值。更多还原

【Abstract】 Spacecraft designers are faced with such new challenges as more complex space missions, shorter design durations and more tightening budgets. The traditional design philosophy becomes insufficient for the needs of the economic development and military applications. At the same time, the“faster, better, cheaper”philosophy is spreading in the design community. And the rapid development of virtual prototyping offers a technical basis for the concurrency engineering based innovations in design methodologies. With the goal of constructing functional-behavioral virtual prototypes (VPs) to support spacecraft design, this dissertation discussed the relevant techniques such as modeling/simulation methodologies, realization frameworks, software implementations, etc.In order to model the complex physical systems of multi-energy domain, a novel modeling methodology named the extended multiport approach (XMPA) was presented. In this methodology, the interactions between components are classified as energy interchanging and signal interacting, through the corresponding interfaces, energy ports and signal ports, respectively. The signal ports are further classified as event ports and continuous signal ports. Then, the whole system is constructed by connecting the involved components through their ports. From such concepts, a formal definition of VP was put forward. With this notion, the system hiberarchy can be described definitely. Furthermore, the virtual prototype view model was addressed, and each view is an implementation of the concerned VP.A formalized model of hybrid automata, namely the Multiport Hybrid Automata (MPHA), was introduced. In the MPHA, discrete transitions and continuous dynamics are described by Actions and Variables respectively. And the event interactions between subsystems are realized through the corresponding event ports, while the continuous ones through continuous signal or energy ports. Then, the connection operation between MPHAs was defined. Such notions are capable of describing the various interactions between subsystems, the hybrid dynamics inside a system or a block and the system hierarchy as well.A framework supporting the functional-behavioral modeling and simulation was presented. The Modelica language together with Dymola, a Modelica based software, and the Matlab/Simulink platform compose the modeling layer of the environment. And the DCOM technique was adopted to support distributed simulation. Additionally, the Modelica library was extended and a methodology for quickly translating Simulink models to DCOM components was developed.As an instantiation, one XMPA based functional-behavioral VP of some spacecraft attitude control system was implemented. This VP is composed of four modules as followed, the structures-and-mechanisms subsystem module, the attitude determination and control subsystem (ADCS) module, the C&DH module and the local environment (LoE) module. These modules are connected through their ports. Each module contains several mathematical models, i.e. the sunlight-pressure torques acted on a spacecraft with a cubical body, a planar antenna array and a pair of symmetrical solar sails and the momentum-wheel dynamics with bearing frictions, flywheel imbalances and structural vibrations considered, etc. The spacecraft’s hiberarchy was depicted in Modelica. And the MPHA models of all levels of the system were defined. Then, respectively, the above four modules were compiled into DCOM components, of which the VP was constructed. Several simulations were conducted to investigate the sunlight-pressure torques, inner disturbances of reaction wheels, compensation for reaction-wheel frictions, momentum dumping using magnetic torquers and switching between controllers. Through such simulations, the above models and the VP modeling methodologies were validated.A VP environment supporting spacecraft ADCS design and analysis was implemented. This environment contains two parts, the modeling and simulation (M&S) environment and the spacecraft working visualization environment.The M&S environment runs on the basis of associated functional modules. For each module, there are two forms of existence, Simulink blocks and DCOM components. It is easy for the user to add new models, modify and update existing ones. Correspondingly, the software provides two running modes, the single-computer running in a Matlab engine and the distributed running basing on DCOM components. With this software, it is convenient to construct an ADCS configuration and analyze the system’s performance.A spacecraft working visualization environment based on the Win32 multi-thread mechanism was realized. The geometric entities used were modeled by OpenGL and MultiGen Creator. Driven by data from other simulation programs, the software is able to provide animations of the orbital and/or attitude motions of spacecrafts, as well as coverage areas of various onboard payloads, either online or offline. The communication between the environment and other programs was accomplished though SOCKETs. This environment has been successfully applied in simulations of multi-satellite systems and spacecraft attitude dynamics.Through the above investigations, the methodologies for constructing functional-behavioral VPs of spacecrafts were established and a feasible implementation approach based on system integration techniques was explored. Such achievements, in the sense of implementing whole functional-behavioral VPs of spacecrafts, are significative and valuable.更多还原