Evaluation and Redesign of Simplified Decouplers for TITO Processes Using Relay Experiments

Effective decoupling is not always achieved due to unavoidable model mismatch or change in the operating point. Thus, evaluation and redesign of the decoupler may improve performance. The redesign of decouplers is a subject that received little attention in the literature. In this paper, a methodology to evaluate and redesign simplified decouplers for two-input two-output (TITO) processes in open-loop using relay experiments is proposed. The decoupler redesign aims at achieving an effective decoupling at two frequencies of interest. The initial decoupler is evaluated by applying a relay-based excitation signal with two frequency components to the decoupled process. The initial decoupler is redesigned to eliminate the decoupler error at each one of the frequencies. Simulation and experimental results are used to illustrate the effectiveness of the methodology.