The paper studies the problem of fuzzy adaptive event-triggered control for a class of pure-feedback nonlinear systems, which contain unknown smooth functions and unmeasured states. Fuzzy logic systems (FLSs) are adopted to approximate unknown smooth functions and a fuzzy state observer is designed to estimate unmeasured states. Via the event-triggered control technique, the control signal of the fixed threshold strategy is obtained. By converting the tracking error into a new virtual error variable, an observer-based fuzzy adaptive event-triggered prescribed performance control strategy is designed. The key advantage is that the proposed method does not require the priori knowledge of partial derivatives of system functions, i.e., it relaxes the restrictive condition that the partial derivatives of system functions need to be known for pure-feedback nonlinear systems. Simulation results confirm the efficiency of the proposed method.

The problem of adaptive fuzzy control is investigated for a class of non-triangular structural stochastic switched nonlinear systems with full state constraints in this paper. A remarkable feature of the non-triangular structural nonlinear system is the so-called algebraic loop problem in existing backstepping-based analysis and design. Properties of fuzzy basis functions are utilized to circumvent the algebraic loop problem. Based on the Barrier Lyapunov function (BLF), an adaptive fuzzy stochastic switched control scheme is designed. It is proved that all the signals in the closed-loop system are semi-globally uniformly ultimately bounded (SGUUB) with full state constraints. The effectiveness of the proposed control scheme is verified via simulation studies.

This article studies the disturbance observer-based adaptive fuzzy finite-time control issue of strict-feedback nonlinear systems. Specifically, to meet practical application requirement, the finite-time prescribed performance is considered, which can guarantee the tracking error enters into the prescribed bounded set in a known time. A disturbance observer is proposed to estimate the external disturbance. It is proved that the closed-loop system is semi-globally practically finite-time stable. Finally, simulation studies for a one-link manipulator are shown to verify the effectiveness of the proposed approach.