An Observer-Based Composite Nonlinear Feedback Controller for Robust Tracking of Uncertain Nonlinear Singular Systems With Input Saturation

Abstract

This study proposes an observer-based Composite Nonlinear Feedback (CNF) controller for the robust tracking of uncertain singular systems with input saturation, nonlinear function, time-delay, and disturbances. The suggested control law is designed based states reconstructed using a singular observer so as to increase steady-state accuracy and improve robustness. The CNF controller is developed based on Generalized Riccati Equations (GRE) and Lyapunov–Krasovskii functional. Additionally, the proposed theorem verifies the stability conditions of the system in the presence of uncertainties and disturbances. Among the advantages of this method, are its fewer restrictive assumptions, transient and high-speed performance improvement and steady-state precision. The uniform boundedness of the tracking error in the presence of the input saturation and external disturbancesis also a prominent feature of this method. The performance of the proposed approach is assessed using a simulation study.

Keywords

• Generalized Riccati equation
• singular systems
• observer-based composite nonlinear feedback
• robust tracking
• nonlinear functions