Finite-Time Fuzzy Preassigned-Performance Control for Nonlinear Systems Subject to Asymmetric State-Constraints Based on Command Filter

This article presents a novel command-filter-based finite-time fuzzy preassigned performance adaptive control approach for nonlinear systems with exogenous disturbances and asymmetric time-varying constraints. Combining the asymmetric barrier Lyapunov function (ABLF) with preassigned performance control (PPC), it is ensured that the state <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$x_{1}$ </tex-math></inline-formula> satisfies the required asymmetric time-varying state constraints (ATSCs), and the system output y can track the desired signal with achieving preassigned performance indices (PPIs). The command-filter-based control design not only circumvents the computing complexity in the backstepping but also reduces the conservativeness of the assumption regarding the desired signal and the time-varying asymmetric constraints. Additionally, the nonlinear disturbance observer method (NDOM) is employed to effectively estimate unknown exogenous disturbances and enhance the robustness of the closed-loop system. Through rigorous theoretical analysis, the proposed finite-time command filter-based control method effectively ensures that all variables are bounded within a finite time. The practicality and feasibility of the proposed approach are further validated by simulation results.