Control System Design for Reduced Thruster-flexibility Interactions in Space Robots

Space manipulators mounted on an on-o thruster-controlled base are envisioned to assist in the assembly and maintenance of space structures. When handling large payloads, manipulator joint and link exibility become important, for it can result in payload-attitude controller fuel-replenishing dynamic interactions. In this paper, the dynamic behaviour of a oneexiblejoint manipulator on a freeying base is studied, while its parameters are matched with available space-manipulator data. Describing functions are used to predict the dynamic performance of two alternative controller/estimator schemes, and to conduct a parametric study on the in uence of key system parameters. Design guidelines and a particular state-estimator are suggested that can minimize such undesirable dynamic interactions as well as thruster fuel consumption.