Smith predictor with inverted decoupling for stable TITO processes with time delays

This paper presents a new design methodology of multivariable Smith predictor for stable 2×2 time delay processes based on the centralized inverted decoupling structure. The controller elements are calculated in order to achieve good reference tracking and decoupling response, and the obtained general expressions result very simple. The realizability conditions are stated and the particular case of processes with all of its elements as first order plus time delay systems is discussed in more detail. A diagonal filter is added to the proposed control structure in order to improve the disturbance rejection without modifying the nominal set-point response. The methodology is applied to two simulation examples and comparisons with other authors show its effectiveness.