Robust Variable Structure Control for Free-floating Space Robot System with Dual-Arms in Joints Space

In this paper, the kinematics and dynamics of free-floating space robot system with dual-arms are analyzed, and it is shown that the Jacobian matrix and the dynamic equations of the system are nonlinearly dependent on inertial parameters. In order to overcome the above problems, the system is modeled as under-actuated robot system, and the idea of augmentation approach is adopted. It is demonstrate that the dynamic equations of the system can be linearly dependent on a group of inertial parameters. Based on the results, a robust variable structure control scheme for free-floating space robot system with dual-arms with uncertain inertial parameters to track the desired trajectory in joint space is proposed, and a planar space robot system with dual arms is simulated to verify the proposed control scheme. The advantage of the control scheme proposed is that it requires neither measuring the position, velocity and acceleration of the floating base with respect to the orbit nor controlling the position and attitude angle of the floating base. In addition to this advantage, it is computationally simple, because we choose to make the controller robust to the uncertain inertial parameters rather than explicitly estimating them online.