Robust adaptive composite control of space-based robot system with uncertain parameters and external disturbances

In this paper, the control problem of space robot system with uncertain parameters and external disturbances is discussed. With the momentum conservation of the system, the kinematics and dynamics of the system are analyzed, and it is found that the generalized Jacobi matrix and the dynamic equations of the system are nonlinearly dependent on inertial parameters. In order to overcome the problems mentioned above, the idea of augmentation approach is introduced. It is shown that the augmented generalized Jacobi matrix and the dynamic equations of the system can be linearly dependent on a group of inertial parameters with augmented inputs and outputs. Based on the results, a robust adaptive composite control scheme for space-based robot to track the desired trajectories in inertial space is developed. The stability of the overall system is analyzed through Lyapunov direct method. For the proposed approach, the global uniform asymptotic stability of the system is established. In addition, the controller presented possesses the advantage that it needs no measurement of the position, linear velocity and acceleration of the base with respect to the orbit, because of the effective exploitation of the particular property of system dynamics. To show the feasibility of control scheme, a planar space robot system is simulated.