Predictive control of unstable time delay series cascade processes with measurement noise

In this paper, generalized predictive control strategy is applied for unstable time delay series cascade processes. The control structure consists of a secondary loop with a secondary controller designed based on simple internal model control (IMC) method and the primary loop consists of a set-point achievement controller and is designed using synthesis method. Further, a generalized predictor consisting of two filters that deals with time delay, disturbance rejection and noise rejection capabilities is also designed in the primary loop. The filters are designed to ensure internal stability as well. For the predictor, only one tuning parameter is involved, which can be tuned in such a way that a trade-off is attained between disturbances attenuation and performance under uncertainties. In this work, various examples of cascade processes with unstable dynamics and time delay are considered for simulation. Results obtained from simulation reveals that with the suggested predictive control scheme, enhanced closed loop control performances are obtained for both nominal and perturbed conditions both in the presence and absence of measurement noise. The comparison is also verified quantitatively with the literature methods using integral absolute error (IAE) and total variation (TV) measures. (C) 2019 ISA. Published by Elsevier Ltd. All rights reserved.