The Cooperative Co-Evolutionary Differential Evolution And Its Applications For Complex Layout Optimization

At the engineering background of a class of spacecraft layout design, this dissertation aims to provide more efficient layout optimization for layout problems of complex spacecraft using Cooperative Co-Evolutionary Differential Evolution (DE for short). Additionally, National Nature Science Foundation of China and project of Research and Development of a Software Platform for Layout Design of Spacecrafts from China Aerospace Science and Technology Corporation supported this work.The rapid development of space technology and industry has need of more researches on the theories and methods of layout optimization for spacecraft. Spatial layout design is to study how to arrange the instruments and equipment inside (or outside) the vessel while satisfying all kinds of engineering constraints. This layout problem is known as a combinatorial optimization and NP problem in mathematics, and complex system problem in engineering. To solve this challenging and open problem is very important to space industry.DE is proposed by Storn and Price in 1995, which is a stochastic, population-based, and relatively unknown evolutionary algorithm for global optimization that has recently been successfully applied to many optimization problems. Moreover, co-evolution (proposed by Hillis firstly in 1991) is a dynamic optimization method based on current evolutionary algorithms, using split search space and gene coding. This dissertation focuses on how to apply DE and co-evolution to layout problems, including the following contributions:(1) A cooperative co-evolutionary differential evolution (called CCDE) was proposed. Based on DE, CCDE uses a problem-solving framework based on cooperative co-evolutionary approach, and partition a high-dimensional complex search space by splitting the solution vectors into smaller vectors, then use multiple cooperating subpopulations (or smaller vectors) to co-evolve subcomponents of a solution. Additionally, this dissertation also discusses the different methods of problem-decomposition, collaboration methods of each sub-species, and evaluation methods of individual fitness. Lots of numerical experimental results showed that CCDE has a marked improvement in performance over the DE, CCGA (cooperative co-evolutionary genetic algorithm) and GA (genetic algorithm).(2) A cooperative hybrid genetic differential evolution algorithm was proposed. Firstly, a hybrid genetic differential evolution algorithm (GDE for short) was proposed. In GDE algorithm, DE and GA share one common population. GDE generates new individual using mutation and crossover operators of DE. Subsequentially, this new individual is changed by Gauss mutation of genetic algorithms to keep the diversity of population and oscillation oflayout objects. Thirdly; a better individual is selected using selection operator of DE to form a new population. Finally; a loop using the above steps is taken to evolve. Moreover; according to the characteristics of layout problems; based on GDE and cooperative co-evolutionary algorithms; a cooperative GDE is also presented. The experimental result using canonical multi-container layout problem showed that GDE achieved better layout results compared to DE and GA; and cooperative GDE is better than CCDE and CCGA.(3) The optimization models; problem-solving methods (including engineering application of the abovementioned methods); and layout software for a class of spacecraft layout was proposed. Firstly; an optimization models and problem-solving methods for spacecraft layout problems were proposed. Then; optimization software for spacecraft layout was developed. Thirdly; optimization software architecture was proposed; and the key software development technologies were introduced; including development mode; user interface and automatic location. Finally; taking the simplified retrievable artificial satellite and international communication satellite INTELSAT-III as engineering example; the experiments showed that the proposed optimization methods and software were effective to the layout problem of this dissertation.This work is expected to help to improve the theory of DE and co-evolution and make the abovementioned methods be practical in engineering. Moreover; users from space industry had checked the proposed software prototype for spacecraft layout problems. Furthermore; this work would be extended to apply in layout of tank; mechanical engineering; robot; rocket; submarine and under-water suspension engineering; etc.