Disturbance Observer-Based Fast Finite-Time Adaptive Fuzzy Control for Uncertain Nonlinear Systems

This research focuses on developing an adaptive finite-time tracking controller for a class of non-strict-feedback nonlinear systems. The controller design addresses multiple challenges, including input saturation, both matched and unmatched external disturbances, and model uncertainties. Adaptive fuzzy systems are employed to approximate a set of uncertain nonlinear functions. An adaptive fuzzy disturbance observer is constructed to enhance control robustness. Most importantly, by designing virtual controls as smooth functions and using finite-time filters, the proposed control is free from singularity. The proposed control strategy's efficacy has been substantiated through numerical simulations.