Research on the dynamic coupling of the rigid-flexible manipulator

•The “Virtual Stewart platform” is introduced to obtain a homogenous matrix to describe how much base motion is produced by a given platform motion.•An index is proposed to characterize the dynamic coupling of the rigid-flexible manipulator.•Based on the proposed index, the factors influencing the dynamic coupling are investigated.•Influence of the dynamic coupling on the feedback control of the rigid-flexible manipulator is discussed.

Because of its large dimension, a rigid-flexible manipulator was designed to serve as the feed support system in a Five-hundred-meter Aperture Spherical radio Telescope (FAST). The rigid-flexible manipulator is composed of a flexible cable-driven parallel manipulator and a rigid Stewart platform. Motion of the Stewart platform may induce vibration of the cable-driven parallel manipulator due to reaction forces. The goal of this study is to investigate the dynamic coupling of the rigid-flexible manipulator. The “Virtual Stewart platform” was introduced to obtain a homogenous matrix to describe how much base motion is produced by a given Stewart platform motion. On this basis, an index was proposed to characterize the dynamic coupling of the rigid-flexible manipulator. Based on the proposed index, the factors influencing the dynamic coupling are investigated. The proposed index can be considered as a performance index in design and control of the system. Influence of the dynamic coupling on the feedback control of the rigid-flexible manipulator was also discussed. The simulation results showed that the dynamic performance of the rigid-flexible manipulator is strongly determined by the proposed index.