Methodology for control of a space robot with flexible links

A methodology of stable manipulation-variable feedback control of space robots with flexible links for avoiding static target and continuous path tracking is discussed. The proposed methodology is effective for base-fixed robots with flexible links on the ground, as well as free-flying space robots. A virtual rigid manipulator (VRM) concept is introduced and a pseudo-resolved-motion rate control for flexible manipulators is derived. By using the VRM, other controls, including an extended local PD-control and a pseudo-resolved-acceleration control, are given. They can be transformed into joint-variable feedback controls and are robust stable. Combining those controls with a reduced-order modal control yields a composite control. The asymptotic stability of the static target is verified by the Lyapunov method. For path tracking control, the orbital stability is discussed in terms of the singular perturbation method. Numerical simulations demonstrate the effectiveness and feasibility of the proposed method