Decoupling Smith predictor design for multivariable systems with multiple time delays

In this paper, a new design approach to the multivariable Smith predictor controller is proposed for decoupling and stabilizing multivariable processes with multiple time delays. A decoupler is first introduced in this new control scheme and a frequency domain approach to the decoupler design is given. To achieve better performance, additional delay items may be added to diagonal elements of the decoupler matrix. With this decoupler, the multivariable Smith predictor controller design is simplified to multiple single-loop Smith predictor controller designs. A frequency domain approach to the model reduction of the decoupled process is proposed and a design method for PID type primary controller is presented. Simulation examples are included to illustrate the effectiveness of the method, and significant performance improvement over the existing multivariable Smith predictor control schemes has been achieved with the proposed approach.