A discussion of the performance of the Smith delay compensator for systems with an appreciable time delay

A discussion is presented of the performance of the Smith delay compensator (SDC) of Smith predictor during the closed-loop operation of continuous linear systems with an appreciable time delay. The basic principle of the SDC is to design the closed-loop system in such a way that the system response is a delayed version of the delay-free system response, where the delay is the plant transport lag. Difficulties inherent in the SDC are briefly mentioned with suggestions to compensate for them. An example of the SDC scheme is illustrated in the closed-loop sodium nitroprusside regulation of postoperative blood pressure.<>