Dynamic isotropy design and analysis of a six-DOF active micro-vibration isolation manipulator on satellites

Abstract The payload and strut mass plays significant roles in the dynamic analysis of Stewart platforms. However, until now there is little literature considering these effects on optimization and vibration isolation. In this paper, a new decoupling condition of stiffness matrix is proposed base on elegant algebraic approach, with which the dynamic isotropy index can be expressed in terms of natural frequencies. When the height of the mass center of the payload is zero, dynamic decoupling as well as translational and combined dynamic isotropy can be satisfied at the same time. Since the dynamic mass matrix is coupled when the height is not zero, an objective function that concerns the dynamic isotropy index and strut masses is formulated. The effects of the strut masses and payload on the natural frequencies and dynamic isotropy index are discussed. The genetic algorithm and differential evolution algorithm are implemented to obtain the suitable parameters for optimization design and vibration isolation purpose. That the optimization results of the two algorithms are nearly the same indicates that the optimized configurations are convincible. On the basis of the optimization process, we take into account a real link and fabricate a real optimized configuration in our laboratory. The dynamic model is also verified by both horizontal and vertical experimental results. It can be concluded that after optimization, a combined dynamic isotropy configuration is achieved, and the frequency range of vibration isolation can be extended.