Research On Behavior Characteristics Of Mechatronic Product And Its Sustainable Conceptual Design Methodology

Conceptual design is the initial stage, also one of the most important stages, of product design process. In the past few decades, researchers have done a lot of works on conceptual design theories and methodologies, where functional design has been given particular emphasis. The function-related works include requirements analysis, functional abstraction, functional decomposition, behavior mapping, design generation and evaluation, and so on. Behavior is used as a link between function and structure to facilitate the design synthesis of complex problems, and it could also assist designers to explore the insight of a design and to develop the design solution.On the other hand, as people concern more and more on environmental issues, sustainable design is being gradually accepted as a necessity for product design. In recent years, applying sustainable design methods in conceptual design process to reduce the product life cycle environmental impacts have become a focus of design research.This thesis explored the behavior characteristics of electromechanical products, and proposed an extended causal behavioral process (E-CBP) model. A sustainable design methodology was subsequently proposed by exploiting this E-CBP model.Firstly, the thesis put forward a definition of behavior, and identified the relationships among behavior, function, structure. By exploring the behavioral characteristics of electromechanical products, we found there are temporal relations, loop relations, state relations besides causal relations between behaviors. We have as such defined "occurred before" and "occur in parallel", which can be used to describe the temporal relationship between behaviors. A representation method based on sequential diagram was also proposed to represent temporal relationships, which can facilitate the identification of temporal relations for designers. We have applied a critical path method (CPM) to optimize the behavioral process for maximizing the productivity of the product being designed. We have identified trigger behavior, revert behavior and main behavior in loop relation, and summarized the characteristics of loop relations and the guidelines that are used to guide the design process. State relation is used to represent the behavior of energy storage mechanisms and those of the mechanisms with intelligent materials.To address the limitations of the original casual behavioral process (CBP) model, an E-CBP model was subsequently proposed, which is an extension of the original CBP model by introducing the temporal relations, loop relations and state relations. The steps of establishing the E-CBP model were elaborated, so was the mapping process from behavior domain to structure domain based on the E-CBP model. A uniform representation, which was based on EBNF (Extended Backus-Naur Form) grammar and exploited the object-oriented programming ideas, has been proposed to represent the E-CBP model. Additionally, the representation has been extended to represent design information such as function, structure, constraints and materials. This representation scheme has not only provided a basis for design knowledge reuse and management, but also facilitated the computer implementation.To meet the demand of sustainability in design, a sustainable design method based on the E-CBP model has been proposed, which used in the conceptual design stage. The method includes an E-CBP based pre-analysis and a multi-level fuzzy sustainable assessment. By applying the E-CBP model and function sharing principle, we have summarized six sustainable design guidelines to improve the E-CBP model to fulfill sustainability requirements. Considering the uncertainty and ambiguousness of design parameters in conceptual design, a multi-level fuzz sustainability assessment method was proposed to evaluate the sustainability of design alternatives.In order to assist designers, a computer aided conceptual design system, which is based on B/S architecture, was developed. The system consists of the E-CBP analysis module, the sustainability assessment module, the basic library module and the basic user interface module. The system is scalable, platform independent, user friendly, and so on.By using this software system, an electric nailing device and an electric polishing device have been studied. The results demonstrated that the proposed E-CBP model and E-CBP based sustainable design method are feasible and effective.