A Method for Designing Decoupled Filtered Smith Predictor for Square MIMO Systems With Multiple Time Delays

Abstract

The control of multi-input and multioutput (MIMO) systems with multiple time delays is difficult to be done using classical control techniques, especially if the process is not open-loop stable. Model predictive control (MPC) is the natural choice in industry for this case, but its tuning and implementation are not trivial and, in general, cannot be done in the low level of the process control system. This paper aims to show a method to design MIMO filtered Smith predictors for n × n processes with multiple time delays based on the decentralized direct decoupling structure. This method allows an easy tuning of the primary controller by simplifying the problem to multiple single loops if the realizability conditions presented in the paper are met. The proposed method can also be used in MPC to remove the interactions between process variables. The effectiveness of the method is illustrated through two case studies.