On the interaction of flexible modes and on-off thrusters in space robotic systems

Space manipulators mounted on a on-o thrustercontrolled 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 payloadattitude controller fuel-replenishing dynamic interactions. In this paper, the dynamic behavior of a exiblejoint manipulator on a freeying base is approximated by a single-mode mechanical system, while its parameters are matched with available space-manipulator data. Describing functions are used to predict the dynamic performance of three alternative controller/estimator schemes, and to conduct a parametric study on the inuence 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.