【作者】 彭晓东；

【导师】 刘波； 孟新；

【作者基本信息】 中国科学院研究生院（西安光学精密机械研究所） ， 光学工程， 2008， 博士

【摘要】 近二十年来,人们对系统工程的研究重心呈现出一种与开发过程截然相反的发展趋势。这在软件工程领域尤为明显,即从早期关注测试阶段开始,渐渐的转向了代码的生成,随后重心又偏向了程序的管理和设计方法,而到了近十年,大量的研究又集中在了开发早期的概要设计和需求分析阶段。这样一种从后向前的逆向研究趋势是因为人们在实践中发现:1)描述具体而实在的问题很容易,而表达更抽象的问题却很难。“我们对一个方案的编码丝毫不感到有困难,真正的麻烦在于去如何描述问题。”2)确定“要做什么”比“怎么做”重要,许多的实际开发经验证明,开发后期发现的系统中的重大错误往往来自于不正确的需求分析或对问题的不准确理解。因此,它体现出这样一个结论:即决定系统开发成败的重要因素往往是开发早期阶段的分析与设计。这对软件工程是如此,对系统工程是如此,对于系统工程的一种、与软件工程有紧密联系的仿真建模工程也是如此。而在仿真建模工程中,承担早期分析与设计这一角色的就是仿真概念模型SCM(Simulation Conceptual Model)。简单的说仿真概念模型是为了满足仿真应用目标而对真实世界进行的首次抽象,它为领域专家、开发人员和验证人员提供了与真实世界一致的、规范的描述,为后期的设计提供支持与指导。对它的建模方法和开发过程的研究也自然成为当今仿真建模领域的热点。将仿真概念模型引入到具体的仿真工程中,起到准确描述问题、把握需求、引导设计开发、便于验证的重要作用,是所有SCM仿真学者的目的,也是本文研究的最终目标。尤其是对于本论文关注的问题域—空间探测任务的仿真来说,要实现仿真概念模型应用,就必须有一套针对空间探测任务特点的、科学简明的建模方法和开发过程。然而,国际上关于仿真概念模型的研究现状是至今还没有统一的、被大家所公认的定义和方法,大家在理论和较抽象层面上还存在分歧,更不用说具体的模型描述方法和开发步骤了。因此论文在总结前人的观点和工作的基础之上,率先提出了针对空间探测任务的详细的仿真概念模型模板SESCML以及其开发过程SECDP,具体的:首先总结了仿真概念模型的一般含义和作用,为后续的研究确定了理论基础。随后分析了空间探测任务的任务类型、运行环境、仿真需求等特征,归纳了国际上几种典型的关于仿真概念模型内容的观点,详细研究了仿真概念模型在仿真系统开发中的位置。并在空间探测任务特征和SCM开发位置的指导下,以总结的内容为基础,确定了针对空间探测任务的仿真概念模型(SESCM)的内容结构。在SESCM内容结构的基础上,论文进一步研究了SESCM的建模方法,通过分析被广泛使用的结构化方法和面向对象方法的特点,确定了以面向对象为基础、结构化方法为过程的仿真概念模型的建模思想。以此为指导,结合仿真建模的一般原则,提出并建立了针对SESCM的建模语言与模板SESCML。SESCML包括系统层、模型层、设计层三个层次,实体模型、功能模型、过程模型、环境模型四类模型,仿真目标列表、仿真背景描述、实体结构图、任务流程图等15种图表模板。文中对各个层次、模型、图表目标的含义、作用、表达方式和相互关系做了详细的研究与论述。为了支持基于SESCML模板的仿真概念模型的开发,论文提出了SESCM的开发过程模型SECDP。SECDP建立在一般建模理论的基础上,贯穿了从知识获取到知识建模的整个生命周期,系统、全面地总结和归纳了SESCM开发过程中的关键活动,并把这些活动划分为五个步骤。重点针对其中的模型验证,研究了它的基本含义与原则,并且提出了SESCM验证的初步的评估的手段和一般的验证步骤。最后,以中俄火星探测任务为研究对象,以SECDP为指导,SESCML模板为标准,依次进行了仿真目标分析、问题域特征分析、建立模型、建立联邦关系等开发活动,最终比较系统和规范的建立了火星探测任务的SESCM。更多还原

【Abstract】 Within the last two decades, the emphasis in systems engineering research appears to follow a reverse of the development path. This trendency is especially typical in software engineering. Software systems research had an early focus on the testing phase, and then a transition is seen to code generation, followed by program organization and design methodology, and for the past ten or more years the sights have centered on the requirements analysis phase and conceptual design phase. Explanations of the reverse path of research emphasis are from practical project experience: 1) Making concrete representations of a solution possibly is simpler than abstract representations of a problem. "We are not really having a problem coding a solution—we are having a problem understanding what solution to code." (Cook, D.1999). 2) Determining "what to do" is more important than "how to do". So much experience from practical project reveals that the high cost or fatal mistakes are often incurred by incorrect requirements analyzing and incomplete understanding of the problem. Therefore, all of these facts come to a conclusion, which is that the critical factor of determining whether or not the simulation can support its intended uses is problem-domain analysis and concept design in the early stages of a project development. That is obviously true for software engineering, system engineering, and simulation engineering which is a kind of system engineering and has the codependency relationship with software engineering. In modeling&simulation, that plays a role which progresses problem-domain analysis and concept design in the early stages is Simulation Conceptual Model (SCM).In short, SCM is the first step on the road to abstract this real world for fulfilling the simulation application object, it provides SME, developer and VV&A agent the normal description according to the real world, which supports and guides the following design. Correspondingly, the research about its modeling method and exploring process becomes the hotspot of today’s modeling&simulation area. Inducting SCM into the concrete simulation project plays significant roles on describing problems accurately, making requirement clearly, directing design development and examining conveniently. What mentioned above is pursued by all the SCM researchers, and also seemed as the final purpose of this paper. Especially for the problem-domain—simulation about space explore target, in order to realize the SCM application, it is necessary to build a deeply concrete scientific simple modeling method and developing process which focus on special characteristic of space exploration mission. However, the international situation about SCM is that uniform definition and method have not been formed because of the differences from theory and disparity on high-level, to say nothing of the concrete modeling description method and exploring process. Therefore, based on the conclusion of predecessors’ opinion and works, we first propose the detailed SCM template of space exploration mission—SESCML, and its developing process—SECDP.First of all, general signification and roles of SCM was summarized, which established theory basis for continuing studying. Characteristics of space exploration mission, such as mission classification, runtime infrastructure, and simulation requirements and so on, were analyzed. Several typical views on content of SCM were summed up. The position of SCM in the process of simulation system development was investigated in details. In the guideline of characteristics of space exploration mission and the developing position of SCM, and based on the summarized contents, the framework of simulation conceptual model aimed at space exploration mission was confirmed.Based on the framework of SESCM, the modeling method of SESCM was researched in further. By analyzing features of structural and object oriented methods, a modeling ideology of simulation conceptual model was founded, for which object oriented method lays foundation, which use structural method as modeling process. In this direction, combining general principle of simulation modeling, the SESCML, modeling language and model template, which aimed at SESCM was brought forward and established. SESCML consists of three levels—system level, model level, and design level, four models—entity model, function model, process model and environment model, and 15 kinds of diagram templates, such as Simulation Objective Lists, Simulation Context, Entity Structure Diagram, Task Flow Diagramand so on. Significations, roles, representions and interrelationships of all kinds of levels, models and diagrams were expounded in this article.In order to support the development of SCM that based on the SESCML template, this paper proposes SECDP-- the developing process model about SESCM. SECDP is built on the foundation of general modeling theory and it exists during the entire lifecycle from knowledge acquiring to knowledge modeling. Also, it concludes the fatal activity systematically and comprehensively, which are consisted of five steps during the exploring process of SESCM. Focusing on the model validation, this paper studies VV&A basic meanings and principle; meanwhile, we propose the primary assessment method and general conceptual validation process.At last, based on the research of Mars exploring, guided by the SECDP, and planed by SESCML template as the criteria, we finished lots of exploring activities such as simulation object analyzing, characteristic analyzing, modeling, and establishing federate relationship and so forth. Thanks to these activities, we finally build the SESCM of Mars exploring target systematically.更多还原