Coordinated robust control based on extended state observer of dual-arm space robot with closed chain for transferring a target

Abstract

The coordinated control problem of free-floating dual-arm space robot with closed chain is discussed. First, dynamic equations of the open-chain space robot system with virtual cut-off point are obtained by Lagrangian equation; the constraint equations of closed loop are derived by the kinematics analysis. The dynamic equations without redundant degree of freedom of dual-arm space robot with closed chain are established by the constraint equations and the theory of pseudo-inverse. Second, in order to achieve excellent tracking performance, the robust control based on extended state observer is proposed for the closed-chain system with uncertain inertial parameters. The unknown part of the closed-chain system is compensated by an extended state observer. The global uniform ultimate boundedness stability with exponential convergence is proven by the Lyapunov’s theory. For the existence of the controller redundancy, based on the weighted minimum-norm theory and pseudo-inverse theory, the joint inputs are distributed for each joint to guarantee the uniqueness of joints trajectory. At last, the numerical simulation is conducted to verify the effectiveness of the proposed control scheme.