Analytical formulas for quasi-H infinity control of linear systems with time delay

A controller design method is presented in the frequency domain for the control of single-input/single-output stable and unstable systems with time delay. A heuristic design procedure is developed on the basis of the developed results of H infinity optimal control theory. Thus the design method is referred to as "quasi-H infinity control". The desired closed loop transfer function is constructed and explicit analytical formulas for controller design are derived. The stability and robustness of the closed loop system are also discussed. The advantage of the proposed method is that it is simple and analytical. Several numerical examples are given to illustrate the new method.