Observer-based optimal and robust output regulation for nonlinear systems

This paper investigates the output regulation problem using an observer-based inverse optimal controller within the nonlinear servomechanism framework for asymptotic convergence to desired references and rejection of time-varying disturbances generated by an exosystem. To address the practical constraint of full-state measurements, the system's internal and external state estimation is done via a full-order high-gain observer. These estimated states are incorporated into the inverse optimal controller augmented with a conditional servocompensator within the Lyapunov redesign and saturated high-gain feedback framework to enhance transient performance and achieve asymptotic steady-state regulation. The proposed control scheme combines the optimality and robustness properties offered by the state feedback controller with disturbance rejection and state estimation in an output-feedback framework. The proposed output-feedback controller is validated on a nonlinear DC motor using MATLAB/Simulink. Finally, comparative simulations against baseline controllers further exhibit the robustness, performance, and practical feasibility of the proposed controller for high-performance control tasks.