Decentralized direct adaptive fuzzy control scheme for state-constrained interconnected systems

Abstract

This paper focuses on the problem of decentralized adaptive fuzzy tracking control for state-constrained interconnected systems. However, feasibility conditions on virtual controllers are imposed by barrier Lyapunov function (BLF) based approaches. To remove it, a nonlinear state-dependent barrier function (NSBF) is proposed, based on which the constrained interconnected system is equivalently transformed into a non-constrained one. Nonlinear interactions and uncertainties are approximated by fuzzy logic systems (FLS). A decentralized direct adaptive fuzzy control (DAFC) scheme is developed, in which a class of reduced-order smooth functions is fused with backstepping control design procedures, and only one adaptive law is used in each decentralized controller. With the proposed control scheme, not only the feasibility conditions but also the partial-derivative terms are not involved in virtual controllers, and the time derivative of the Lyapunov function is ensured negative semi-definite. It is shown that the proposed control scheme guarantees that the state constraints are not violated, and the tracking error converges to a predefined interval asymptotically. Two simulation examples confirm the effectiveness of the proposed control scheme.