A multi-segment serial–parallel spatial closed-chain capture mechanism based on bionic principles

Abstract. With the rapid increase in the number of spacecraft, the number of various non-cooperative targets and failed spacecraft has risen sharply. Consequently, dealing with these targets requires the actuator to possess high flexibility, high enveloping ability, and structural stability. Following bionic principles, this paper proposes a multi-segment serial–parallel spatial closed-chain capture mechanism. The mechanism is formed by coupling a single parallel capture mechanism composed of four-URU four-branch parallel mechanism and double-loop folding expansion platform. First, the configuration design of the single parallel capture mechanism with the core structure of the double-loop folding expansion platform plus the four-URU four-branch parallel mechanism is carried out. Secondly, the motion screw system and screw-constraint topological diagram of the mechanism at the initial position are obtained through the null-space method, and then the DOF of the mechanism is calculated. Subsequently, a kinematic analysis of the capture mechanism is performed. Finally, simulations and a prototype model are developed to verify the motion feasibility of the multi-segment serial–parallel spatial closed-chain capture mechanism.