General Information
    • ISSN: 2010-0221 (Print)
    • Abbreviated Title: Int. J. Chem. Eng. Appl.
    • Frequency: Biannually
    • DOI: 10.18178/IJCEA
    • Editor-in-Chief: Prof. Dr. Shen-Ming Chen
    • Executive Editor: Alice Loh
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Prof. Dr. Shen-Ming Chen
National Taipei University of Technology, Taiwan

IJCEA 2010 Vol.1(4): 290-293 ISSN: 2010-0221
DOI: 10.7763/IJCEA.2010.V1.51

Improved PI Controllers Tuning in Time-delay Smith Predictor with Model Mismatch

S.Shokri 1, M.Shirvani2, A.R.Salmani3, M. Younesi4

Abstract—The problem Dead Time in control systems is an everlasting problem which is of primary importance in process control as well. The estimation and compensation of processes with time delays have been of interest to academics and practitioners for several decades. The first proposed solutions for this problem was the Smith predictor in 1957. It was based on the idea of removing the time-delay from the characteristic equation of the control closed loop, which seemed to be very attractive at the first.Later investigations revealed that the method is very sensitive to model mismatches, which results in destabilizing effects on the loop performance.  In this paper, using work it was propose a new method for controller tuning using an optimization method. The optimization method is based on dominating the gain of the minimum phase term in the open loop transfer function of the loop, such that the non-minimum phase effects of the model and process become dominated by the minimum phase characteristic of the desired term. This idea was investigated by simulation on some selected examples among the proposed modified versions of the Smith predictor.

Index Terms—Smith predictor, Stability,Time-Delay, Model Mismatch,Optimization Tuning Algorithm, dominant gain.

1 Scientific member of Research Institute of Petroleum Industry (RIPI),West Blvd. Azadi Sport Complex, Tehran, Iran
2 Assistant Professor, School of Chem. Eng., Iran Univ. Sci. Tehran., Iran
3,4 Chemical Engineering Department, Iran University of Science andTechnology, Tehran, Iran Corresponding author : Tel.: +9848252503; Fax: +982144739713 (e-mailaddress:


Cite: S Shokri, M. Shirvani, A .R. Salmani and M. Younesi, "Improved PI Controllers Tuning in Time-delay Smith Predictor with Model Mismatch," International Journal of Chemical Engineering and Applications vol. 1, no. 4, pp. 290-293, 2010.

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