In the following, the discrete sliding mode control (DSMC) is utilized to achieve the synchronization. Generally, the DSMC design is composed of two steps. First, we need to select an appropriate switching function for error dynamics (7) such that the sliding motion can ensure the convergence of the error states. Second, we need to propose a DSMC to guarantee the existence of the sliding mode and maintain the error dynamics on the sliding manifold [2]. To achieve the synchronization based on DSMC, a switching function is selected as: