Space-based robot manipulators: Dynamics and adaptive control

The autonomous operation of free-flying robots in space requires the manipulation of objects with unknown inertia properties. As a result, the combined inertia parameters of the end-effector and load cannot be determined a priori. This problem entails further research in the application of adaptive motion control strategies for space robots. Crucial to successful controller design is an accurate model of the underlying highly coupled nonlinear dynamics of multi-body space robots. Current techniques which use momentum conservation laws to obtain reduced order differential equations of motion provide models which do not depend affinely on the unknown inertia parameters of the robot system. Consequently, new models have to be developed to allow the synthesis of adaptive control strategies.;This dissertation is concerned with the modeling of free-flying space robots and the design of adaptive motion control strategies. Specifically, we examine the generic case of articulated manipulator arms mounted on a satellite base which may or may not contain reaction wheels for satellite attitude control. The basis for our approach is the formulation of analytical models which depend affinely on the unknown inertia parameters of the system.;Using these models we develop an adaptive joint space controller for the manipulator joints and an adaptive inertial space controller for the manipulator end-effector. A novel feature of our approach is that the parameter estimates are obtained using integrals of the motion only. Moreover, recursive algorithms are provided for efficient implementation of the adaptive controllers. Other new results in this work include the use of unit quaternions in defining orientation errors of the end-effector. This leads to adaptive control schemes which stabilize the robot system. Rigorous proofs of the stability properties are established using Lyapunov stability theory. Furthermore, simulation studies of the adaptive control schemes on two example space robot systems are used to verify the theoretical results.