An alternative EPSAC based control strategy for multivariable time delay processes

Multivariable time delay processes are difficult to control due to the input-output interactions, as well as multiple time delays that complicate the controller design process. The proposed method presented in this paper consists of a dynamic decoupling strategy - compared to the more general used steady state decoupling techniques - and a delay time compensation (DTC) structure in which the controller is designed based on the Extended Prediction Self Adaptive Control (EPSAC) approach. The main concern regarding the proposed method is directed towards the possible lack of robustness against time delay variations - a problem that is frequently encountered in DTC structures. Moreover, the decoupling technique implemented consists in adding supplementary time delay to some input channels of the MIMO process, which may result in a worsening of the robustness problems. The simulations presented show that the proposed method can ensure robust stability and robust performance even for significant time delay variations.