Genetic Programming And Its Application Research In Creative Design Of Mechanism

Genetic programming (GP) is proposed on the basis of the genetic algorithm (GA), which is a global probability search algorithm that use natural choice thinking and genetic mechanisms. As GP can realize adaptive optimization by intelligent search, it has been widely studied and applied.First the theoretical knowledge of GP is studied deeply, some improved methods are proposed to overcome some shortcoming of simple genetic programming(SGP). Average generation is used to get higher quality initial groups to accelerate optimization process and improve the convergence properties. Fitness function based on fuzzy-function is set up, which make the evaluation on the individual more reasonable. The compulsory individual mutation and local compensating operators are introduced to overcome shortcoming of big randomness and slow velocity of convergence. Simplification operator is introduced to limit individual explosion and control the growth of individual trees. The effectiveness of improved GP is proved by curve fitting example.GP is applied in the cam contour curve design because GP has the advantage of curve fitting. The kinetic rule curve of the follower of cam mechanism is separated for data points, with the distance of the given data points and the data points of the design curve as the original fitness function, GP is used to carry on the fitting of the cam theoretic contour curve, and the analytic function of cam contour curve is achieved, which can realize the automatic design of the cam contour curve.The goal of mechanism innovatory design is to have new mechanisms that can meet the design requirements, in the first phase of the mechanical products design, that is the overall program design can break the traditional design methodology, from design selection to design configuration. Therefore, GP is applied in mechanism type creative design, research mechanism creative design, discuss new theories and new methods of mechanism type design, develop software of mechanism creative design based on GP. Firstly, mechanism is made into tree structure type, generate initial mechanism tree population. Secondly make genetic operation to the individual in the population, uses weighted coefficient score to evaluate mechanism in the course of genetic evolutionary, then get outstanding mechanism trees that meet design requirements and draw mechanism figure of outstanding mechanism trees. The creative method simulates the mechanism deduction with the natural evoluation process, realizes breakthrough of mechanism type, produces new mechanism types that meet design requirements, solves the question of one-sidedness of artificial construct mechanism and dependence of design experience, realizes selection of mechanism on the computer automatically. The method is applied in examples of mechanism creative examples, and mechanism type that meet design requirments can be got.