Approximation Based H∞ Control of Linear Systems with State Delays

In this paper, we address the control design problem of time delay systems based on delay-free approximation models. By exploiting the asymptotic proprieties of the deviance between the time delay system and approximate system trajectories, an H
∞
output feedback control with mixed sensitivity for setpoint tracking was developed. We have compared two approximation methods for control design: Galerkin's approximation and a state dimension preserving approximation. Numerical simulations are also presented to show the applicability of the approximation-based H
∞
control.