A ROBUST STABILIZATION CONTROL FOR DUAL-ARM SPACE ROBOT CAPTURING TUMBLING TARGET

Due to the inaccurate inertia parameters of the captured tumbling target and the internal wrenches at the grasping points, the motion of the space robot stabilizing the tumbling target cannot be planned and controlled effectively in the post-capture phase. In the existing studies, it is risky to track the desired trajectory planned by inaccurate parameters, which cannot restrain the contact wrenches and guarantee the safety of the grasping points. In order to control the post-capture dual-arm space robot safely, a robust control scheme is proposed for the dual-arm space robot capturing a tumbling target in this paper, where the influences of the inaccurate target inertia parameters and the internal wrenches at the grasping points are considered. First, a robust invariant set is constructed considering the influences of the inaccurate target parameters and internal stress wrenches. Then, to plan a safe desired motion for the dual-arm space robot, a virtual robust control law for the captured target is developed, where the desired trajectory of the target is planned within the constructed invariant sets. By the motion constraints between the space robot and the target, a robust desired trajectory of the dual-arm space robot is obtained. A barrier Lyapunov function based constrained controller is developed to track the robust trajectory efficiently. By tracking the robust trajectory with prescribed control performance, the designed virtual control law is applied to stabilize the captured target. During the stabilization control process, the measured contact wrenches can be restrained by the proposed scheme effectively, which guarantees the safety of the grasping points and the reliability of the stabilization control. The effectiveness of the proposed scheme is validated via the digital simulations, where a non-cooperative tumbling target is stabilized by a dual-arm space robot.