Study On Intelligent Control Strategy For Large Aspheric Mirror Polishing Process

Aspherie optical elements are being used more and more widely in modern optics systems,due to their ability of correcting aberrations, enhancing the image quality, enlarging the field of view and extending the range of effect, while reducing the weight and volume of the system.The manufacture of large aspherical mirrors often reflects the compositive scientific and technological strength of a country. As an indispensable stage of the manufacture of large aspherical mirrors, the shape error and surface quality of aspherical grinding forming affect the total efficiency of the whole process. With the ever-increasing demands on optical system performances, requirements for aspheric optical components are more and more critical, which involve aperture, relative aperture, accuracy, lightweight extent, manufacturing efficiency and cost. The technology of computer controlled stressed-lap polishing is a relatively new optical burnishing technology for large aspherical mirrors, which can actively deform the lap surface to an off-axis aspheric surface according to different lap positions on the mirror surface and different angles of the lap. In large optical component processing, computer-controlled active stressed lap polishing has a number of advantages, such as high processing efficiency, natural smoothness, and production of a smooth surface and sharp edges. Although computer controlled stressed lap processing has advantages in the fabrication of large aspheric surfaces, there are some difficult problems, such as modelling uncertainty of the stressed lap, high non-linearity and a high performance requirement of the optical processing, especially for deep off-axis aspheric surfaces. This thesis is dedicated to solve the key problems in stress-lap polishing technique, in order to consummate stress-lap polishing technique and improve capability for manufacturing large and medium aspheric surfaces. The major research efforts include the following points.①the demands of aspheric surfaces in the world were introduced. The importance of optical systems using aspheres and the trend of optical systems were introduced.The research background of this thesis and the techniques of aspheric fabrication in the world were introduced.②Analysis of this stress the basic principles of plate processing and the technical route, structure characteristics of the stress lap is given and stress lap shaped detection method. ③Through studying the relationship between input and output data of stress-lap, and analysis of the correlation between the variables and proposed the corresponding analysis method, stress-lap structure characteristics is given, and stress–lap shaped detection method is proposed.④Summarizes the latest intelligence control technology, combining the characteristics of stress-lap, we present a new, facilitate online implementation of the fuzzy RBF neural network in which the knowledge expression of fuzzy logic is combined with fast learning speed and generalization of RBF neural network ,as controlled the flexible body stres-lap intelligent control scheme.⑤To design intelligent control systems, to facilitate a computer controlled optical polishing process, a neural network based stressed-lap surface shape model was developed. The developed model can reflect the dynamic deformation of stress lap .The original data from the micro displacement sensor matrix were used to train the neural network model, use the established model for simulation and Contrastive analysis combination of different drivers to get simulation of stress-lap shape change.⑥Basis in the dynamic change of the surface shape of the stressed lap during the operating process of polishing a large aspheric optical surface is investigated. The principle and structure of neural network based shape control system are discussed. The relationship between the stressed lap driven forces and surface shape is analyzed in detail. The original data from the micro displacement sensor matrix were used to train the neural network model, and do Comparison of simulation results for model.⑦Based on the design of stress-lap intelligent control system ,we was developed with good man - machine interface the stressed-lap intelligent control system simulation platform.⑧the research contents of this thesis were summarized. And the innovations and the significance of this thesis were summarized.