Stabilization and robust control of a class of processes with long time delay

A compound P+I control system is presented to deal with the control of stable process with long time delay in this paper. An extension of the Hermite Biehler theorem applicable to quasi polynomials is used to stabilize the proposed system. The robustness of the system is analyzed. The system responds to the setpoint as quickly as the Smith-predictor-based control system. But it is less sensitive to the model uncertainty even the mismatch of parameters is up to 10 times.