The Control Methods Research Of Space Membrane Reflector With Electrodes

With development of earth observation and space optics, the space membrane reflector(MR) can break constraints between the needed high resolving power and the restricts of space and weight in the process of setting up because of merits of large aperture, low area density, folded or unfolded and low cost. Compared with other control methods, MR stretched by electrostatic forces can be controled freely and precisely with an attractive application foreground. At present, some developed countries in space navigation have researched MR technology and got many material works, such as America and Russia. But it is at the initial stage for exploring research in China.Though there are many advantages, the control of MR stretched by electrostatic forces is very difficult because of its complex affecting factors. Primarily, a MR test device controlled by a single electrode has been constructed in our lab but without accepted figure result, while that controlled by distributed electrodes is considered to be an important method to get a better surface. So the control methods and experimental structure design of MR stretched by distributed electrodes are studied in this paper. Based on these, the control and test experiments with a polyimide membrane are completed, and the affecting factors and control rules are analyzed and concluded. The theory analysis and experimental results indicate that MR controlled by distributed electrodes is better than that controlled by the single electrode.First, the active and passive affecting factors of the membrane surface are analyzed, which provide references to the control method study and experimental structure design of MR. The problem of MR controlled by electrostatic forces can be boiled down to an inverse solve problem about membrane forced to deform, and it is analyzed from continuous exerted load method and discrete equal exerted loads method. For the former method, based on shell theory without moment the continuous exerted load function changed with membrane radius is deduced with consideration of the membrane pre-stress factor. The curve format of continue load is defined. The native reason of MR control is understood, and a reference for control and design of electrostatic MR is given. Whereas discrete electrodes in the actual control method must be used, then the inverse solve problem of discrete equal exerted loads method is studied. From the approximate analytical solution of Poisson's equation, the inverse solution is expatiated by the method of least-squares fitting, and a finte element coupling model of electrostatics - structure is also given, and the localization of the both methods are analyzed. Besides, the method of linearizing the nonlinear large deflection is also studied. At the end, the finite element numerical optimize method is feasibly given for the experiment control of MR with distributed electrodes.Based on the theoretical analysis, an electrostatic polyimide MR support structure with effective aperture of 300mm and 10 electrodes in three annuluses is design and built. Primarily tests have been done on plane membrane surface, light concentrating and surface controlled by single annulus electrode. Using the optimized distributed pressure data solved by the finite element numerical optimize method, the membrane control and measurement experiments have been done, and the results indicate that the flexible membrane surface controlled by distributed electrostatic forces is feasible, and a set of methods about experiment and membrane control of the large electrostatic MR are primarily formed.The research work in this paper lays the groundwork for the next work about precised surface control of electrostatic MR study, and thoroughly study of MR technology and its practicablity.