Non-contact Shape Control Based On Hierarchical Genetic Algorithms

Along with the rapid development of space science and technology, there are more and more flexible parts in the space structure, and the space structure’s shape need to be kept in high precision during a long time. In order to ensure the working performance of the space structure, we must conduct non-contact shape control on the flexible parts.This paper focuses on the investigation of non-contact shape control of beam structure and plate structure with surface bonded photostrictive actuators. The procedure of the hierarchical genetic algorithms and the mechanism of the PLZT photostrictive actuators are discussed in this paper. Based on the Timoshenko beam theory, an accurate PLZT laminated element in taking into account shear and peel stress in adhesive layer is developed and then the finite element analysis formulation under the multiphysics’ effects with optical-electric-mechanical-thermal coupling is derived. On this basis, a new control method is proposed by combining hierarchical genetic algorithms and finite element method. In this method, the topological distribution of photostrictive actuators and the light intensity are chosen as design variables and the shape errors between the desired shape and the achieved shape is taken as the fitness function. The distribution of photostrictive actuators and the light intensity are optimized by using hierarchical genetic algorithms(HGA) and finite element method. The performance of the present method for shape control is assessed in comparison with that of the conventional genetic algorithm. The results demonstrate that the maximum absolute error between the actuated shape and the expected one has been reduced by over 65.5%, and the root mean square error has been reduced by more than 73.3% compared with the conventional genetic algorithm.