Modified Smith Predictor for Controlling Integrator/Time Delay Processes

Astrom et al . have proposed a new Smith predictor to control the process with an integrator and a long time delay. Though the method provides significant performance improvement, it fails to give effective tuning rules even when the integral constant is equal to 1. In this paper the method is extended to the general integrator/time delay process. A clearer and more logical design procedure is formulated, and simple tuning rules are developed. It shows that there is a minimum-order compensator for the process. Illustrative examples show the superiority of the proposed scheme in terms of both closed-loop performance and robustness.