Global terminal sliding mode robust control for trajectory tracking and vibration suppression of two-link flexible space manipulator

In this study, based on differential geometry input-output linearization method, a new robust control approach using global terminal sliding mode (GTSM) was developed for trajectory tracking and vibraton suppression of two-link flexible space manipulator, and the nonminimum phase control problem was solved. Firstly, the system outputs including joint angle and flexible-link vibration were redefined and therefore, the manipulator system was decomposed into input-output subsystem and zero-dynamics subsystem by input-output linearization. Secondly, in order to make the tracking error of input-output subsystem fast convergence to zero in finite time, a GTSM control strategy was designed, which was able to eliminate significantly the chattering inherent in conventional sliding mode control. Moreover, by analyzing the relationship between the eigenvalues of zero-dynamics and the parameters of controller, the zero-dynamics can be quickly and asymptotically stable at equilibrium point by choosing proper parameters. Consequently, the whole original manipulator system was guaranteed to be asymptotically stable. Finally, the presented numerical simulation results demonstrated the effectiveness and feasibility of the proposed control program.