Evolutionary Technique And Its Application In Computer-aided Conceptual Design

Evolutionary technique is a universal technique in solving problems, which develops on the basis of 'survival of the fittest'. Coding technique is employed in evolutionary technique to express complex structures. In evolutionary technique, study is guided and searching directions are determined by genetic operations on coding strings. Not only does evolutionary technique have high efficiency, but it is also universal and easy to be implemented. And these merits are just part of the main reasons why it is favorable.Evolutionary technique has shown a great potential to work out several real-world problems in the point of optimization, but it is still quite far from realizing a system of matching the human performance. Especially, in creative applications such as architecture, art, music, and design, it is difficult to evaluate the fitness because the measure depends mainly on the human mind. It is becoming a study focus how to combine fitness function and partial order theory to construct a new method for evaluation.In this paper. Chapter 1 presents a general introduction to evolutionary technique and computer-aided conceptual design. Then it discusses the progress of evolutionary technique in CACD. followed by the analysis of the main problems in this researching field.Chapter 2 is devoted to evolutionary technique. First, it analyzes the characteristics and the classification of evolutionary technique, uses genetic algorithm (GA) in illustration of how to design evolutionary algorithms (EAs). introduces basic theorems of GA, analyzes astringency of GA, and presents a uniform standard for astringency. Then a kind of GA based on tree structure is reviewed. Finally, it presents an evolutionary technique based on partial order, followed by the process in solving conceptual design problems with this technique.Chapter 3 investigates the theories and techniques of conceptual design. First, it introduces the definition of conceptual design and computer-aided conceptual design, and summarizes the main issues in the progress of researches on CACD: methodology of conceptual design, product information modeling, resolution mechanisms of conceptual design and CACD technology. Then it introduces 3 methods of conceptual design, which are employed in this paper: the method based on combination principle, evolutionary design method and case-based reasoning method, and introduces the technique of product information modeling. Finally, it presents a resolution mechanism of conceptual design by combining traditional method, combination principle and evolutionary design.Chapter 4 presents a conceptual design system based on evolutionary technique. First, it presents the structure of the system, pointing out that the system consists of 3 parts: the modulebased on evolutionary technique to generate creative components, a database of three dimensional models and the module based on evolutionary technique to generate creative designs. Then it introduces the 3 parts respectively. In the module based on evolutionary technique to generate creative designs, the module evaluates designs according to a partial order constituted by several evaluating objects. In addition, the module integrates computer evaluation and artificial evaluation. If no obvious improvement is achieved in these designs after several generations, a message will be sent to interactive EA by the interface between interactive EA and independence EA. Then artificial evaluation will be made for these designs to work out satisfactory creative designs. Finally, the efficiency of the system is proved by experiment data.A study is conducted on evolutionary technique and its application in CACD in this paper. It is hoped that it could promote the development of evolutionary technique and its application in CACD.