Adaptive Fuzzy Control for Nonstrict-Feedback Systems With Input Saturation and Output Constraint

TLDR

The study proposes an adaptive fuzzy control method for uncertain nonstrict‑feedback systems with input saturation and output constraints. The method uses a variable separation strategy, an auxiliary design system to handle input saturation, a barrier Lyapunov function for output constraints, and combines fuzzy logic with adaptive backstepping to guarantee semi‑global boundedness and drive the tracking error toward the origin. Simulations confirm the closed‑loop stability and demonstrate the effectiveness of the proposed control scheme.

Abstract

This paper presents an adaptive fuzzy control approach for a category of uncertain nonstrict-feedback systems with input saturation and output constraint. A variable separation approach is introduced to overcome the difficulty arising from the nonstrict-feedback structure. The problem of input saturation is solved by introducing an auxiliary design system, and output constraint is handled by utilizing a barrier Lyapunov function. Combing fuzzy logic system with the adaptive backstepping technique, the semi-global boundedness of all variables in the closed-loop systems is guaranteed, and the tracking error is driven to the origin with a small neighborhood. The stability of the closed-loop systems is proved, and the simulation results reveal the effectiveness of the proposed approach.