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Journal of Engineering
Volume 2014, Article ID 409014, 13 pages
Research Article

Robust Tension Control of Strip for 5-Stand Tandem Cold Mills

1Department of Automation Engineering, Tandem Cold Rolling Mill, Mobarakeh Steel Company, Isfahan, Iran
2Department of Electrical Engineering, Faculty of Engineering, University of Isfahan, Isfahan, Iran
3Department of Electrical Engineering, Najafabad Branch, Islamic Azad University, Isfahan, Iran

Received 3 July 2014; Accepted 8 October 2014; Published 5 November 2014

Academic Editor: Xiao He

Copyright © 2014 Behrooz Shafiei et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Tandem cold rolling process is a nonlinear complex system with external and internal uncertainties and significant disturbances. The improvement in the quality of the final output depends on the control strategy of centerline thickness and interstand tension. This paper focuses on interstand tension control problem in 5-stand tandem cold rolling mills. Tension dynamics can be described by a nominal model perturbed by parametric uncertainties. In order to overcome the model uncertainties and external disturbances, suboptimal and controllers are proposed and the Hankel-norm approximation is used to reduce the order of controller. The performance of the proposed controllers is demonstrated by some simulations.