Dynamic modeling and control of a free-flying space robot with flexible-link and flexible-joints

Free-flying space robot´s nonlinearity and strong coupling characters make the dynamics and control of such system more complicated than a terrestrial robot system. The Space robots are always built in very light for saving the launch energy. The flexibility of the joints and links is considerable arising from its elasticity. Controlling this manipulator is more complex than controlling one with rigid joints due to the interactions of rigid and flexible motion, in which only a single actuation signal can be applied at each joint and has to control the flexure of both the joint itself and the link attached to it. To discussing an under-actuated flexible-link flexible-joint space manipulator, a free-flying space manipulator with one flexible link and two flexible revolute joints is presented in this paper. The dynamical Lagrange equation is established, and a singularly perturbed model has been formulated and used for designing a reduced-order controller. This controller consists of a rigid control component and two fast control components. Numerical simulations show that the link and joint vibrations have been stabilized effectively with good tracking performance.