Information representation and constraint satisfaction for the domain mapping process of product design.

摘要

In the highly competitive marketplace of today, how well a company designs its products is critical for its survival and success. To ensure that product design will satisfy customers' expectations with low cost and short development time, several design methodologies have been developed. In these methodologies, the mapping from the functional domain to the physical domain is particularly important because all subsequent design activities are based on the decisions at this stage. However, due to a lack of constraint modeling and satisfaction, the decisions are supported with partial information. Consequently, a product may be successful in achieving a specific function while failing certain product life cycle requirements. To reduce product development time and cost, such problems should be identified and avoided as early as possible.;To overcome the shortcoming of the existing design methodologies, a constraint-based product design methodology is developed in this research. This methodology includes an information representation scheme, a decision model for product concept selection, and a general constraint satisfaction algorithm for parametric value assignment. The representation scheme models different types of design information and their relations. Functions, product concepts, performance measures, physical parameters, constraints, and preferences are defined and used consistently in the design process. With the relations of design information, functional coupling strength and coupling strength of concepts with respect to constraints are assessed quantitatively. Based on the quantifiable coupling strength, the decision model selects product concepts with minimal coupling and maximal performance ratings. Given the information of constraints, the general constraint satisfaction algorithm reduces the solution space of physical parameters and then assigns values to these parameters using a genetic algorithm. An example of gear train design is used to demonstrate the capabilities of the constraint-based product design methodology.;The representation scheme, the decision model, and the general constraint satisfaction algorithm are capable of modeling and satisfying both functions and constraints at the early design stage. These capabilities overcome the shortcoming of the existing design methodologies and support engineers in the design process from the functional domain to the physical domain.