Research Of The Key Techniques On Micro-vibrations For The Space Optical Payload

With the development of space technology, space telescopes with large aperture and high-resolution imaging are playing an increasing role in many fields of military, commerce, astronomy, and civil use. However, micro- vibrations produced by the onboard equipment in spacecraft(such as control momentum gyros, reaction wheel assemblies, solar panel deployment actuators, cryogenic coolers and other motion devices) will seriously degrade the image quality of the space telescope. Micro-vibrations have the characteristics of low amplitude, a wide frequency range, and multiple directions. Moreover, the large space telescope is very complex and involves multi-disciplinary knowledge. As a result, the present vibration suppression methods and analysis techniques are difficult to meet the development needs of the large space telescope. So it will be of great importance for the large space telescope to research the techniques of micro-vibration suppression, integrated opto-mechanical analysis and ground simulation.A novel compact vibration isolator which is used for the space payload in orbit is designed. The structural parameters of the isolator are analyzed. The arrangement forms of the isolator which are suitable for different space payloads are researched. A vibration isolation system is manufactured to test the vibration isolation performance of the isolator. Considering the characteristic of the viscoelastic material whose stiffness and damping properties vary with frequency and temperature, an analysis approach which is based on the compact stiffness method is presented. The analysis results are consistent with the test results, which indicates the proposed method used to the design and analysis of the isolator is valid and reliable. Meantime, these isolators are applied to the vibration isolation of one space optical remote sensor. The analysis results show that the isolators can effectively attenuate the micro-vibrations of the optical payload transmitted from the mounting surface.The multidimensional vibration isolation system(VIS) which is used for the vibration isolation of the whole optical payload is researched. The theoretical model of the VIS is developed, as well as the generalized stiffness matrix and the damping matrix. The algebraic expressions which can be used to calculate the natural frequencies of the VIS are then derived. In addition, the optimal design methods are proposed to obtain the optimal configuration. To verify the isolation effect of the VIS, an integrated opto- mechanical analysis method based on the finite element method(FEM) is addressed. This integration simulation analysis combines the structural model, optical model with control model and all the calculation can be completed by using the FEM. As a result, it has the advantages of high accuracy, efficiency and less exchange data.To reproduce the micro- vibrations generated by the disturbance sources in spacecraft, a micro-vibration simulator(MVS) based on the Gough-Stewart platform is proposed. The New-Euler method combined with Lagrange approach and Kane method are adopted to derive the dynamic models of the two simulators, respectively. A co-simulation using ADAMS and MATLAB/Simulink is employed to verify the validity of the dynamic models. According to the test results of the first generation MVS, a bivariate surface fitting method is applied to correct the control algorithm of the MVS. The test results show that the correcting algorithm can greatly enhance the operation performance of the MVS. Considering the fact that there are differences between the theoretical model and the actual physical model, the control strategies used for the second generation MVS are researched. A robust proportional- integral(PI) controller based on the inverse dynamic models is then designed. The theoretical analysis and simulation results show that the proposed robust PI controller has excellent robustness and stability, and can be used for acceleration control of the MVS.