Design of a SMC-based fuzzy controller for nonlinear systems

In this paper, a fuzzy controller based on sliding mode control (SMC) is proposed. The control strategy of the proposed sliding mode control is characterised by the linguistic terms in the fuzzy control rules. All membership functions of fuzzy control rules are well defined to guarantee the stability of control systems. The design strategy relies on the following stages: first, it develops an adaptive law to approximate the equivalent control of sliding mode control, while the mathematical model of the nonlinear system is unknown; second, it adds a hitting control term to translate arbitrary state to a prespecified sliding surface. Finally, a novel fuzzy controller with two linearity control rules, which not only applies the sliding mode control rationale but also guarantees the stability of fuzzy control system, is constructed. A nonlinear simulation example is applied to confirm the validity of the fuzzy controller