The interface was regarded as standard and not considered in traditional configuration design, which made it difficult to apply to the existence product configuration. The paper proposes an extension case-based reasoning for product configuration design. With matter-elements, reasoning model of Extension Case-Based Reasoning (ECBR) is established, and its corresponding algorithm is proposed. During the configuration design, the solution space of configuration schemes is obtained by the similarity calculation, and then the overall evaluation of similarity and compatible degrees is adopted to form the final configuration scheme. A prototype system of reducer configuration design is successfully developed according to the method, and it proves the proposed method that is feasible and effective.

Common platform design for product families is an important step in the modularity field. It is impossible to find the similar components in alterative design stages for the traditional similarity measure used in module division. So, a new common platform design method on extension-distance is presented. In different design environments, three distance concepts are discussed, namely, feature-to-feature, feature-to-set and set-to-set. The first concept will be employed as the base for extension-cluster method in the platform design on the thought of each structure’ s features between two adjacent structure components, while the second is used to build the tolerance-constraint function in the customized components division for the common platform generation. Last the adaptability measure is used to find the optimal case in the database. The method took the gasoline saw as an example.