Optimal trajectory tracking control of robotic manipulator system added by discrete-time fast terminal sliding mode...

In this study, the problem of trajectory tracking optimal control of robotic manipulator system subjected to external load disturbances is investigated, and an observer-based discrete fast terminal sliding mode predictive optimal control (FTSMPC) strategy is presented. Firstly, to address the unknown friction torque and load disturbances, a novel discrete-time extended state observer is designed to estimate the lumped disturbances, in which the boundedness of the observation error can be guaranteed through theoretical analysis. Then, with the outputs of the observer, an FTSMPC control approach is designed. In this control scheme, the reaching phase is optimized by designing a predictive input torque controller, which not only enhances the trajectory tracking response performance effectively but also makes the input torque curve smoother. Moreover, the theoretical stability proof of the system is verified strictly. Finally, a simulation case and an experimental application are carried out, and the comparison results show the excellent control performance of the proposed method.