Robust H∞ control method of time-delay systems based on Smith predictor

A design method of H_∞ robust controller based on Smith predictor is presented. By analyzing the properties of the Smith predictor, the robust performance of a time-delay system is converted into a delay-free one. This not only makes the analysis and synthesis easier, but also avoids of the rational approximation of time-delay that can result in performance deterioration. Theoretical analysis and simulation shows that the design method not only eliminates the time-delay but also improves the robust performance of the system signally. This work contributes direct application of current robust control toolbox to time-delay systems.