Parallel cascade control of dead time processes via fractional order controllers based on Smith predictor

In this paper, control of stable, unstable and integrating processes with large time delay in the presence of uncertainty, external disturbances and measurement noise is investigated. For this purpose, fractional order controllers in the parallel cascade scheme based on smith predictor are designed. The applied parallel cascade control strategy consists of a set point tracking controller, a disturbance rejection and a stabilizing controller. Set point tracking and disturbance rejection controllers are fractional order controllers and stabilizing controller is designed based on Routh-Hurwitz stability criterion. Also, the robust stability and the performance of the proposed strategy are studied in some details. The numerical simulation results are used to make comparisons with the other researchers' works to show superiority of the designed controllers. (C) 2019 ISA. Published by Elsevier Ltd. All rights reserved.