Robust observer-based H ∞ controller design for linear uncertain time-delay systems

In this note, we present a robust observer-based H∞ control design method for linear time-delay systems with norm-bounded time-varying uncertainties. Using the Riccati-equation-based approach we design observer-based feedback control laws, which guarantee the quadratic stability of the closed-loop control system and reduce the effect of the disturbance input on the controlled output to a prescribed level.