Design, Simulation And Analysis Of The Surface Shape Control System For Membrane Mirror

With the development of the space optical system and the elevation of the requirement for its spatial resolution, the research and manufacture of large aperture and ultra-lightweight space telescope has become one of the main tasks in space science area. The membrane mirror with a substrate of flexible film has characteristics of lightweight, compact-deployable and low cost compared to the traditional one and it is prospected to be applied in future large space optical systems.The surface shape control is one of the key technologies for the manufacture of membrane mirror. Based on the shaping method of membrane mirror that is being researched, this dissertation has designed a surface shape control system for membrane mirror which is on the basis of fuzzy logic control technology and hoped to provide a technical support for further experimental studies.The research background and progress of the membrane mirror and its'surface shape control are introduced firstly. Then, some basic theories for surface shape control system design are discussed. The features and effects of using Zernike polynomials to fit the mirror's shape data are analyzed, the reason of choosing the fuzzy control technology as the surface shape control method for membrane mirror is explained, and the fuzzy control theory and the design of the fuzzy controller are illustrated.According to the requirements of the surface shape control of membrane mirror, the architecture of the surface shape control system is designed. The system consists of such modules as surface shape design, surface shape control and correction, surface shape control simulation, surface shape analysis, and etc. The work procedures of the system are explained in detail, the implementation of the core modules of the system is discussed, and the system integration solution is established.The simulation and analysis of surface shape control of membrane mirror are performed by using the designed system. The shape control methods for membrane mirrors with different apertures and F numbers applied by uniformly distributed or non-uniformly distributed load are simulated both in theoretical analysis mode and in finite element mode. Stability and reliability of the system are tested via shape control simulation and disturbance response simulation. The results of simulation show that the RMS wavefront error of the membrane mirror under non-uniform load can be controlled and improved in two orders of magnitude comparing to that of the membrane mirror under uniform load.