Determination of Ranged Sets of Design Specifications by Incorporating Design Space Heterogeneity

Setting design specifications (targets) is a critical task in the early stages of a design process. Flexible targets can accommodate uncertainty and changes in design by postponing design commitments and preserving design freedom. In this work, a new method is developed for obtaining a ranged set of design specifications that meets design criteria while incorporating design space heterogeneity, meaning some areas in the design attribute space are more achievable than the others. There are two notable features of the proposed method. First, a quantization algorithm based on rough set theory is used to decompose a design attribute space into subregions based on how well they meet design criteria. Second, a new design flexibility measure is used as a metric to select the most desired " target region " based on both the size of the region and the influence of potential design alternatives on overall achievability. The proposed approach enhances the ability of a design system to adapt to evolving design knowledge as well as unexpected changes. The proposed method is demonstrated by a numerical example and the design of a domestic blender. targets Nomenclature a j /A potential design alternative/ set of potential design alternatives D(y) aggregated influence function E s design flexibility over a subregion s in a design attribute space F single or multiple design criteria I j (y) influence function of a design alternative a j