Modified Smith predictor and controller for processes with time delay

A modified Smith predictor and a simple but very effective controller design procedure is proposed for time delay processes. The controller has a simple structure whose high performance particularly for unstable and integrating process is clearly shown. Design of the controllers is based on standard forms of the closed-loop system response with a variable zero and on the optimum stability approach of De Paor and O´Malley (1989) for a proportional controller for an unstable process. Illustrative examples show the superiority of the proposed controller design method over previously published approaches in terms of both closed-loop performance and robustness