The variety of devices which are equipped on spacecraft, such as solar
refrigeration compressor, rotating mechanism, adjusting gyroscope etc., will produce
micro vibrations. The micro vibration has the characteristics of wide bandwidth,
small amplitude and complex form, which seriously affect the image quality of
optical remote sensor in space vehicle. The common solution is to install the
vibration isolation device for optical remote sensor. In order to evaluate the
effectiveness of the vibration isolation device, a large number of ground tests are
needed. The premise of the work is to reproduce the micro vibration spectrum
characteristics. Therefore, it is a subject with great significance to design a micro
vibration simulator which can reproduce with different spectrum characteristics of
micro vibration.
Firstly, the dynamic characteristics of the space micro vibration simulator
based on Gough-Stewart platform are studied. The dynamic model of the
micro-vibration simulator is derived by Newton-Euler’s method, in which the
quality of the legs and the hinge and the eccentricity of the load center are included. The mathematical analytic formula which can calculate the natural frequency and
the main vibration mode of the micro vibration simulator is derived. Through the
finite element simulation and the experimental test, the axial rigidity of a single
driving leg is studied. At the same time, the dynamic characteristics of the first
generation prototype are analyzed with theoretical method and finite element
method. The natural frequency of the micro vibration simulator is tested. The
simulation and test results show that the three methods are consistent with the
natural frequency and the main vibration mode, and the error value of the natural
frequency is not more than 5%. The accuracy of the theoretical model is verified.
Combined with the performance index and the research results of the natural
frequency of the first generation micro vibration simulator, the optimization method
of the system structure is obtained. The driving leg is optimized, and the radial anti
overturning ability of the spring in the driving leg is improved. The structural
rigidity of the hinge is improved, and eliminate the nonlinear problem caused by the
upper and lower hinge in the platform control. The problem that mutual conduction
between the drive legs of the first generation prototype is solved. The finite element
modeling and simulation analysis are carried out for the second generation model,
and the experimental test of the prototype is carried out. It is shown that the structure
design of the second generation prototype achieves the expected goal.
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