A new modified Smith predictor: the concept, design and tuning

The paper presents a new modified Smith predictor ((MSP) for processes with a long time delay. The MSP appears as an extension of the double controlle r-scheme (DCS) proposed by Tian and Gao. The important feature of the MSP i s that the trade-off between disturbance rejection and robustness to variat ions in process parameters can be adjusted by means of a single free parame ter. The main contribution of the paper concerns tuning of the MSPI which r elies on a combination of magnitude optimum criterion with process paramete risation based on multiple integrals of the open-loop step response, In a s imulation study the performance of the MSP is compared with that of two kno wn controllers for time delay systems, i.e. BCS of Tian and Ciao and Hagglu nd's predictive PI controller. The results show the advantage of the MSP co mpared to the two other controllers. (C) 2001 Elsevier Science Ltd. All rig hts reserved.