Direct adaptive output feedback fuzzy decentralized control for a class of large-scale nonlinear systems

A hybrid adaptive output-feedback fuzzy decentralized control methodology is introduced for a class of large-scale nonlinear systems. The proposed controller has a primary-auxiliary control structure, where both directing a adaptive approaches is employed for the primary control part aiming to maintain the closed-loop stability, whilst in the auxiliary part a sliding-mode controller is designed to compensate for the interactions among subsystems and a H-infinity-controller is designed to attenuate the fuzzy approximation errors. It turns out that this hybrid adaptive fuzzy decentralized controller can guarantee the stability of the closed-loop system and also achieve the H-infinity-tracking performance. When used with an observer, the proposed approach can work for processes with unknown states, which is a special feature unique to other existing adaptive fuzzy control methodologies. Simulation results confirm the effectiveness of the proposed control methodology.