Robust Smith‐predictor controller for uncertain delay systems

Necessary and sufficient conditions for the robust stability and performance of the Smith‐predictor controller, modeled under a norm‐bounded uncertainty, are given in a general formulation. In addition, a practical stability condition is obtained as a special corollary of the main results. These conditions provide useful and practical guidelines for the development of a systematic robust design method. In particular, an application is developed for the robust control of first‐order deadtime systems with simultaneous uncertainties in all three parameters of the model. A simulation example and the results of a case study on the robust level control of a coupled‐tanks apparatus are provided for illustration.