Modeling and control of free-flying flexible joint coordinated robots

A system consisting of several flexible joint robots mounted on a spacecraft with closed kinematic chain constraints is studied in this paper. First, the kinematics and dynamics of such coordinated space robotic systems in the presence of joint flexibility and with closed kinematic constraints are established. Using the singular perturbation theory, the entire free-flying coordinated space robotic system is decomposed into two subsystems, one the slow subsystem governing the object position and internal forces, the other the fast subsystem governing the joint elastic forces. A coordinated controller, consisting of a position and internal force controller for the slow subsystem and a joint elastic force controller for the fast subsystem is designed to distribute the load between the coordinated flexible joint robots and to control the object position and internal forces as well as the joint elastic forces.