A unified approach to fuzzy modelling and robust synchronization of different hyperchaotic systems

In this paper, a Takagi--Sugeno (T--S) fuzzy model-based method is proposed to deal with the problem of synchronization of two identical or different hyperchaotic systems. The T--S fuzzy models with a small number of fuzzy IF--THEN rules are employed to represent many typical hyperchaotic systems exactly. The benefit of employing the T--S fuzzy models lies in mathematical simplicity of analysis. Based on the T--S fuzzy hyperchaotic models, two fuzzy controllers are designed via parallel distributed compensation (PDC) and exact linearization (EL) techniques to synchronize two identical hyperchaotic systems with uncertain parameters and two different hyperchaotic systems, respectively. The sufficient conditions for the robust synchronization of two identical hyperchaotic systems with uncertain parameters and the asymptotic synchronization of two different hyperchaotic systems are derived by applying the Lyapunov stability theory. This method is a universal one of synchronizing two identical or different hyperchaotic systems. Numerical examples are given to demonstrate the validity of the proposed fuzzy model and hyperchaotic synchronization scheme.