【作者】 周东祥；

【导师】 王维平；

【作者基本信息】 国防科学技术大学 ， 控制科学与工程， 2007， 博士

【摘要】 随着仿真应用范围的不断发展,建模仿真对象已经发展到包含众多子系统,结构、行为复杂并不断演化的复杂大系统,迫切要求仿真应用能够及时响应领域对象的演化,持续保持对研究对象的有效性与合理性,避免当研究对象发生需求、结构及行为的变化时重新开发仿真系统;并且希望仿真系统的开发能够像工业制造领域一样,通过灵活组装零部件快速形成满足不同需要、结构行为各异的目标系统,从而降低仿真系统开发的费用与风险。组合仿真正是在这种需求背景下提出的一种新的仿真开发思想与范式,已经成为复杂系统仿真领域的研究热点。组合仿真强调最大限度地实现仿真模型的组合与再组合,通过灵活的组装方式快速构建目标仿真系统,并通过模型组件替换实现仿真系统结构、行为的演化发展。当前组合仿真方法大多集中在工程实现层次上,由于缺少组合仿真理论的指导,仿真模型难以组合以及模型组合性质难以定量分析的问题仍然十分突出。如何提高仿真模型的可组合性已经成为组合仿真领域亟待解决的焦点问题。论文以卫星导航系统工程总体仿真为应用背景,以提高仿真模型的可组合性为最终目标,从模型描述及组合性质分析机制两个方面入手,对仿真模型组合理论、多层次建模与仿真集成等重大理论方法问题进行了一定的创新研究和工程实践,主要体现在以下几点:(1)系统地搭建了组合仿真的概念体系,提出以多层次仿真模型描述为核心的组合仿真概念框架CSCF,明确了CSCF中包含的模型、过程实体以及实体之间的组合依赖关系。构造了五种组合模式,为模型组装过程提供了多种选择。建立了仿真模型可组合性的参考模型RMC,深入辨析了可组合性与其它相近概念的联系和区别;建立了组合正确性的概念,以此为基础提出了仿真模型可组合性的分析框架。(2)针对语法层次的四类模型组合失配问题,提出基于类型理论的仿真模型语法描述及组合性质分析机制。通过分析组合失配情形,指出语法层次仿真模型组合的实质是类型匹配问题。基于类型理论对仿真模型定义语言SMDL进行了扩展,通过为其建立一个简单类型系统STS,从而使SMDL具备了对语法层次模型组合进行推理与分析的能力。在仿真模型类型定义的基础上,构造了严格类型匹配、子类型匹配以及弱化类型匹配三种组合匹配关系。基于类型匹配关系建立了组合相容性及可替换性的形式化分析方法,给出了语法层次组合性质分析的关键算法。(3)针对语法上可组合的模型不一定构成有意义(Meaningful)组合的问题,基于Hoare逻辑建立了仿真模型语义描述及组合性质分析机制。提出模型语义描述的分类框架,指出显式、形式化的模型语义描述是促进模型之间的语义共享以及支持语义层次组合性质分析的关键。在Hoare逻辑基础上,提出了基于前后断言的仿真模型语义的形式化描述机制,并针对不同组合模式分别给出了模型语义的组合推理机制;根据模型语义的描述,通过考察模型前置条件、后置条件之间的逻辑关系判断模型是否具备可组合性,分别建立了三种组合相容性和六种可替换性的分析规则,并给出相应算法。(4)提出扩展DEVS的仿真模型动态语义描述及组合分析机制。针对DEVS规范没有明确行为等价性的问题,建立了DEVS执行语义的形式描述,基于互摸拟关系的DEVS模型行为等价性准则,并进一步分析了互模拟等价和系统态射的关系;针对DEVS组合模型规范中端口连接仅关注语法元素而不支持动态行为组合的问题,基于角色—协议—协作(RPC)框架对DEVS规范进行了扩展,以角色和交互协议刻画了DEVS模型在端口(集)上的详细交互行为,以角色的绑定刻画了DEVS组合模型中端口绑定的组合行为,建立了支持语用层次仿真模型组合的RPC-DEVS形式描述规范。为了分析语用层次仿真模型动态语义的组合性质,提出了角色相容性及可替换性的概念,以协作中模型角色的交互协议判断角色是否满足相容或可替换性,给出了角色相容性及可替换性的形式定义,并分别给出相容性和可替换性判定的关键算法。(5)为有效支持组合仿真的建模与集成,提出模型驱动的组合仿真集成框架(MCSIF)。MCSIF明确给出了组合仿真的开发过程,可用于指导实际仿真系统开发,并能有效支持模型组合与再组合过程,提高仿真系统对新需求的适应能力。MCSIF框架利用精确元建模框架PMF支持不同层次的模型描述,PMF框架不仅关注语法层面的模型定义(如接口、事件等),还通过模型转换机制建立语法层次模型描述和语义、语用层次模型描述的关联,不同层次的模型描述都是精确、平台无关的,具有较高的抽象层次,从而构成DTM的全面描述,满足多层次组合建模的需求。PMF框架利用MLF系列元建模语言,面向不同层次分别建立了MSSD元模型、SCM元模型和REM元模型,并建立了元模型之间的映射关系支持模型转换机制,从而保证了不同元模型在模型描述问题上的一致性以及不同层次组合性质分析的相互校准作用。(6)针对卫星导航系统工程总体仿真中的模型组合需求,设计并实现了支持多层次建模及组合的卫星导航仿真辅助开发与集成环境原型CSimTools,支持不同层次的仿真模型描述,提供模型组装环境,支持模型的统一调度执行。以导航系统服务性能仿真应用实例验证了论文提出的仿真模型组合理论与集成方法。论文的研究属于建模仿真理论的基础和前沿性研究,不但丰富和发展了系统仿真方法学,对于促进卫星导航工程总体仿真模型的互操作、重用也具有重要意义,可用于指导和支持复杂系统仿真模型的集成。更多还原

【Abstract】 The research area of Modeling and Simulation (M&S) has moved to the complex huge systems comprised of many sub-systems, whose structure and behavior are keeping evolving. The ability to quickly respond to such evolvements for keeping valid and sound to the real systems is required to avoid developing new simulation systems from scratch when the requirement, structure and behavior of them has changed. The way to build simulation systems like the industrialized making, in which the components were assembled flexibly and agilely to form different target systems is urgently required to reduce the cost and risk of developing a new simulation systems. In this situation, composable simulation was proposed, as a new thinking and paradigm of simulation development, to tackling these current problems, and it has been the research hotspot of M&S of complex systems.The issue about composing and re-composing of simulation models is focus of composable simulation. But current approaches to composable simulation are mostly concerned about the implement details. Without the theory of composable simulation, the composition of simulation models and analysis of model composablity are still very hard. How to improve composability of simulation models has been the key problem and urgently required in the composable simulation.This dissertation makes the general demonstratiion of satellites navigation systems as the application background. To improving composability of simulation models, this dissertation expands its key contents to several correlative directions focusing on simulation model representation and analysis of composability. The original work and the main contributions of this dissertation include:(1) Core conceptual problems of composable simulation are systematically studied. Focusing on multi-level representation of simulation models, the Composable Simulation Conceptual Framework(CSCF) is proposed, in which several kinds of models entities, process entities, and the relationships between these entities are definitely defined and five composition patterns are provided to assemble models. The Reference Model of Composability of simulation model(RMC) was established, which differentiates related concepts such as interoperability, reusability ,etc. The analysis framework of composability is proposed on the concept of composition correctness.(2) Syntactical model representation and composability analysis based on type theory are systematically studied. Firstly four syntactical composition mismatching problems which roots in type mismatching are presented, then Simulation Model Definition Languages(SMDL) was extended with a SMDL simple Type System(STS). Based on the type judgement and type inferring rules, three type matching relations, including exact match, subtype match and the relaxed match, are formally defined. The formal methods of analyzing compatibility and substitutability of models, as well as the key algorithms, are established on these type matching. (3) Semantic representation of simulation models and composability analysis based on Hoare logic are studied. The classification framework of model semantics shows that explicit, formal semantic description is the keys to prompt semantic model composability. The approach to semantic description is proposed on Pre-Post assertions to form the composition reasoning rules. Three compatibility rules and six substitutability rules are constructed to analyze the composability by checking the logical relations between the pre-and post predicates, and the algorithms are provided for these rules.(4) Pragmatic composability concerns about how to use model and what’s the behavior of model, i.e. model dynamic semantic, which represents its interactions with environment or other models. The formal semantic of DEVS specification is defined, and further the behavioral equivalence checking rules of DEVS models based on bi-simulation is provided. The Coupling DEVS specification essentially concerns about syntactical composability between ports, so DEVS is extended by Role-Protocol-Collaboration(RPC) framework to form RPC-DEVS specification. In RPC-DEVS, the roles and its protocols describe the detailed behavior of DEVS port, and the binding of roles characterizes the behavior of the composition of DEVS ports. The approach to analyzing dynamic semantic composability and the algorithms are established on the compatibility and substitutability between roles.(5) In order to effectively support multi-level modeling and simulation integration, the Model driven Composable Simulation Integration Framework (MCSIF) is proposed. MCSIF framework supports rigorous model definition at syntactic, semantic and pragmatic level, and further prompts model composability and reusability. In MCSIF, the Precise Modeling Framework(PMF) was constructed by using Meta-modeling Languages Families (MLF), and the meta-model of MSSD, SCM and REM are designed based on PMF for multi-level modeling. The mapping relationship between these meta-models is studied, which assures the consistency of multi-level model descriptions, and plays the calibration role in multi-level composability analyzing.(6) According to requirements of model composability and simulation integration in general simulation of satellite navigation system, the CSimTools prototype was design and implemented. CSimTools provides series of tools to supports multi-level modeling, composing and simulation integration, and provides a uniform schedule mechanism to support simulation execution. The theory and approach of this dissertation is demonstrated by an example of satellite navigation Service Volume Simulation development.The research topics of this dissertation belong to the fundamental M&S theory category. Above work and contributions can advance the research of simulation methodology, and promote the interoperability and reusability of models in general simulation of satellite navigation system, and can direct the integration of other complex system simulations.更多还原