Study On The Large Deployable Antenna Control At Orbit Using Intelligent Structure

With the development of large diameter and high precision mesh shape antenna reflectors, shape precision control of antenna reflector has become one of the major developing trends of modern space technique. Because use of the control at orbit has great advantage to adapt the antenna reflector to the uncertain environment and disturbance, space organizations all over the world pay more and more attention to this promising technology. The important factor lead to the low precision is the vibration. So the vibration control is imposable.The development of the smart materials and structures provides a new way of thinking for shape precision control, which displays the special vitality. Therefore, combining with the thought of smart materials and structures, intelligent structure of vibration control at orbit of large deployable antenna based on fiber optic sensor, PZT actuator and H∞mixed-sensitivity control method is proposed and studied. The main work is as follows:(1)Based on the completely synthesizing the available research results of smart materials and structures and according to the vibration control for large deployable antenna at orbit, intelligent structure of vibration control at orbit of large deployable antenna based on fiber optic sensor, PZT actuator and H∞mixed-sensitivity control method are put forward in this dissertation.(2)Considered the flexible cable net deployable antenna, the nonlinear static analysis and dynamic analysis formulation of the tensegrity space structure are derived and the calculation method is presented. The dynamic properties of the structure are investigated by calculating a real example.(3)Using some theory of piezoelectricity function and elasticity mechanics to deduce the finite element function of antenna which includes intelligent structure element. And the dynamics function of the antenna is obtained. So the vibration control modal with intelligent structures is established. Due to the high frequency not modeling and the low frequency perturbing, Mix-up sensitive function is applied to H∞control method.(4)According to the problem of placement optimization for the intelligent structures in the large deployable antenna, mode analysis technology is applied to optimize placements of intelligent structures in the mesh shape with the characteristic of large size and flexibility. The strain energy and response of the out force are studied. The response of actuate force is defined. So by weighting the candidate active members strains energy and the response for out force in each mode and the response of actuator force, the information of optimal placements is obtained. A control model example is calculated with the above method.(5)The advanced sensing monitor technology based on fiber optic Fabry-Perot (F-P)sensors is applied to intelligent structure of vibration control at orbit of large deployable antenna. The strain sensing properties of F-P sensors are researched based on coupled-wave theory. In the mean time, the fundamental principles of sensing monitor system are reviewed, the theoretical model for measuring the tensile force and the vibration parameters through measuring strain with F-P sensors is explored. The thesis modal of Signal Noise Ratio (SNR) for sense monitor system is established. Assignment test on the sensing element of large deployable antenna is carried out. The results show that the developed strain sensors using F-P have high precision, high sensitivity, very good linearity, coincidence and simple monitor system. The experiment results indicate that it is application in laboratory.(6)Taking a large deployable antenna as an example, the intelligent structure system is designed and is applied on monitoring and controlling of the large deployable antenna. With the results of simulation, the H∞control method is very effective. This is a successful example that the intelligent structures vibration control by H∞control method, too. Also the experimental research with fiber optic F-P sensor in the laboratory is done. Both the theoretical and experimental study results show that the method presented in this paper can be used to monitor the tension, the natural frequency of vibration and the mode shape.