Decoupled sliding-mode controller based on time-varying sliding surfaces for fourth-order systems

This paper presents a decoupled control strategy using time-varying sliding surface-based sliding-mode controller for fourth-order nonlinear systems. The time-varying sliding surface slope computations are performed by linear functions which are derived from the input–output mapping of the one-dimensional fuzzy rule bases. It is shown that the proposed method not only exhibits a simpler structure compared with the existing decoupled control methods, but also eliminates the need for using fuzzy rules without degradation in performance. Moreover, the proposed method is shown to be asymptotically stable. In order to verify the theoretical considerations and demonstrate the performance of the proposed method, a cart-pole (single-inverted pendulum) system is simulated. Simulation results have shown a considerable improvement of the proposed method in terms of a faster dynamic response and lower IAE and ITAE values as compared with the existing decoupled control methods employing time-invariant sliding surfaces.