Decentralized Adaptive Fuzzy Output-Feedback Control of Switched Large-Scale Nonlinear Systems

In this paper, a decentralized adaptive fuzzy output-feedback control problem is discussed for a class of switched large-scale nonlinear systems without the measurements of the system states. Fuzzy logic systems are used to approximate the unknown nonlinear functions, and a switched observer is designed to avoid the conservativeness caused by adoption of a common observer for all subsystems. A common coordinate transformation of all subsystems is constructed to get rid of individual coordinate transformations for subsystems that are required when applying the backstepping recursive design scheme. Meanwhile, since the exponential decline property of Lyapunov functions for individual subsystems is no longer satisfied in this paper, the classical average dwell time method cannot be directly applied. Based on this, a switched observer-based decentralized adaptive fuzzy output-feedback control technique is set up by exploiting the average dwell time method and backstepping. It is proved that all the signals of the resulting closed-loop system are semiglobally uniformly ultimately bounded under a class of switching signals with average dwell time, while the tracking errors converge to a small neighborhood of the origin. The effectiveness of the proposed control scheme is illustrated by its applications to a two-inverted-pendulum system and a quadruple-tank process system.