Research On Case-based Reasoning For Product Conceptual Design

With the rapid development of market economy, the competition between enterprises becomes more and more vigorous. How to reduce the cost of product, increase the abilities to meet an emergency of market and fast reaction. Those become the main target of enterprises. Quote price of the traditional enterprises is based on experience, or the price is accounted after accomplishing the product design. There are some shortcomings such as slowing down the quoted price, lack of scientific foundation, lack of the ability of meeting an emergency of market. In order to resolve those shortcomings, utilize the network techniques and intelligent product planning design method, according to the needs of customers, realize the fast planning design of product. This thesis is a part of fast quote systems for electromechanical product. The main purpose of this thesis is to exploit a system for product conceptual design that is based on case-based reasoning technology, and supply a theoretic foundation for this system, which makes the quote system scientific, quick and accurate.It puts forward a knowledge representation method of object-oriented model, which is abstracted from the relational data. It is applied in the conceptual design systems of deceleration machine. It is proved that the method could resolve the complicated and structural knowledge representation effectively and screen the bottom database effectively. So it can be transplanted.This thesis discusses the classification network model of conceptual product cases, uses the Roughset theory to determine the importance of each key feature and answers the question of heavy value in power of key case feature in similarity measurement. It puts forward a case retrieve strategy and algorithm; that is to say, retrieve the cases by the combination of the nearest approach and the knowledge-based retrieve approach. Firstly, establishes the knowledge index item with knowledge-based retrieval approach. Secondly, accounts the degree of similarity of all cases in the case database and the new problem with formula of computation of the degree of similarity on the base of the nearest neighbor approach. Finally, retrieves the best similar case by sorting the degree of similar case.It uses the Access 2000 to establish the similar case-base model to simulate conceptual product. As programming language, the Visual Basic.NET programs the case-base and establishes the visualized retrieve interface. That realizes the quick index of the similar case of the deceleration machine conceptual product. The system is applied in the product conceptual design of deceleration machine. It has been proved that the case-based model reasoning is an effective reasoning method. The satisfying result is acquired in product conceptual design. That provides scientific and logical basis for the quote system in network.