Research On Model-based Systems Design Theory And Modeling Methodology

Development of large-scale products such as a satellite or missile has evolved into complex systems engineering methodology,which includes top-down systems design,multidisciplinary development,and bottom-up integration processes.With the considerably increas of functional complexity of a large-scale product,the systems design process is involving more and more design information at different levels and from various domains.Conventional document-based systems engineering approach shows limitations in satisfying modeling requirements of designing the complex product,as systems design information is scattered into different documents,in which the nature texts are difficult in representing sophisticated systems behaviors in a scientific and precise way.Thus,the thesis focuses on the research of model-based systems design theory and modeling methodology.An axiomatic model-based systems design theory for complex products is proposed,a corresponding ontology is constructed,and a functional change propagation prediction method is proposed from a knowledge perspective.The research can provide a basis for the scientific and precise systems design modeling,promote the model-based systems design to the development of matured methods,standard theories,and formalisms.The thesis:(1)Proposes an axiomatic model-based systems design theory that improves the scientificity of the systems design.The mathematical definition of the systems design process from the abstract level to detailed level is established by combining model-based systems design and axiomatic design.General Systems design information like requirements,functions,behaviors,structures,independence axiom,and information axiom are represented consistently.The systems design process can be specified by a requirement-function-behavior-structure framework,in which the behavior is introduced as the bridge between the systems function and structure,and the design axioms are able to specify the optimal design.The proposed approach solves the insufficient scientificity of the systems design,and provides a modeling framework.(2)Establishes ontology of the axiomatic systems design that reduces the ambiguity and re-design caused by the semantic inconsistency.The customer requirement,functional requirement,behavior element,design parameter and design solution ontologies and their relationships during the systems design are formally represented.Reasoning rules of independence and information axioms are created to automatically identify functional couplings and optimal design parameters.The ontology solves the semantic inconsistency resulted from the informal representation of the systems design information and ensures design intentions be human-understandable and machine-readable.(3)Proposes a reuse method of a system model and a general functional change propagation prediction method,which support multidisciplinary information reuse and functional change management.A system model reuse framework consisting of ontology layer,systems design information layer and disciplinary design information layer is constructed.The ontology alignment technology is applied to relate existing design parameters with a specific systems design solution to enable reusing the disciplinary information during the systems design process.A functional change propagation prediction approach from a knowledge perspective is proposed,which is able to predict the change propagation range and probability,so as to dramatically enhance the change management efficiency.According to the above research,a systems modeling software framework is established.The framework can realize representing the meta-model and corresponding ontology of systems design information utilizing the open source system modeling tool Papyrus and ontology editor Protégé.In addition,a system design matrix generation tool,a system model reuse tool,a system integrating design database and a functional change prediction tool are developed.Finally,a case study of systems design of a satellite mission analysis and power subsystem is given to demonstrate the proposed model-based systems design theory and modeling approach.