Decoupling control by hierarchical fuzzy sliding-mode controller

A design method using hierarchical fuzzy sliding-mode (HFSM) decoupling control is proposed to achieve system stability and favorable decoupling performance for a class of nonlinear systems. In this approach, the nonlinear system is decoupled into several subsystems and the state response of each subsystem can be designed to be governed by a corresponding sliding surface. Then the whole system is controlled by a hierarchical sliding-mode controller. In this design, an adaptive law is derived based on the Lyapunov function to tune the coupling factor of the hierarchical sliding-mode controller so as to achieve favorable decoupling performance with guaranteed stability. The proposed design method is applied to investigate the decoupling control of a double inverted pendulum system. Simulations are performed and a comparison between the proposed HFSM decoupling control and a conventional fuzzy sliding-mode (FSM) decoupling control is presented to demonstrate the effectiveness of the proposed design method.