Vibration suppression for post-capture spacecraft via a novel bio-inspired Stewart isolation system

In the process of on-orbit capture mission, some undesirable vibrations arising from the relative motions between the servicing spacecraft and the target are inevitable, which can make the post-capture combined spacecraft unstable or even tumbling. Therefore, suppressing post-capture vibrations is critical to mission success. In this work, a novel bio-inspired X-shape structure-based Stewart isolation platform (XSSIP) system is first proposed to install between the satellite platform and the capture mechanism. It can suppress the post-capture vibrations of a free-floating spacecraft subjected to the impulsive or periodic external forces. Beneficial nonlinear stiffness and nonlinear damping characteristics with the existence of X-shape structure can be acquired, which is helpful to achieve much better vibration isolation performance in multiple directions. Different from the traditional ground vibration isolation system, the dynamic equations of the 6-DOF under-constrained system in the weightless environment of space are established by Lagrange's principle. Influences on vibration isolation performance of the XSSIP system incurred by different structural parameters are systematically studied under either periodic or impulsive excitations. In addition, ADAMS simulation is conducted to verify the accuracy and feasibility of the theoretical model. Compared with the traditional spring-mass-damper (SMD)-based Stewart isolation platform system, the XSSIP system possesses an obvious advantage and offers a highly efficient passive way for suppressing post-capture vibrations of the floating spacecraft.