Journal of Systems Engineering and Electronics ›› 2018, Vol. 29 ›› Issue (3): 611-617.doi: 10.21629/JSEE.2018.03.18

• Control Theory and Application • Previous Articles     Next Articles

Mixed sensitivity H control for LTI systems with varying time delays

Mohamed vall OULD MOHAMED()   

  • Received:2017-02-06 Online:2018-06-28 Published:2018-07-02
  • About author:OULD MOHAMED Mohamed vall received his B.S. degree in electronic from the Faculty of Sciences of Tunis, Tunisia, in 1998 and his M.S. degree in automatic control and signal processing and Ph.D. degree in electrical engineering from National School of Engineers of Tunis (ENIT), in 2001 and 2007, respectively. He was with the Computer Science Department at the Faculty of Sciences of Bizerte, Tunisia, from 2002 to 2010. Since 2010, he has been teaching in the Department of Computer Engineering and Networks, College of Computer Science and Information, Aljouf University, Kingdom of Saudi Arabia. His research interests include robust automatic control, sliding mode, systems identification, network control systems, robust control, delayed systems, text classification, genetic algorithms, and neural networks. E-mail:


Designing a robust controller for a system with timevarying delays poses a major challenge. In this paper, we propose a method based on mixed sensitivity H for the control of linear time invariant (LTI) systems with varying time delays. The time delay is assumed bounded and the upper bound is known. In the technique we propose, the delay affecting the plant to be controlled is treated as an unmodeled uncertainty (in form of multiplicative uncertainty). That uncertainty is approximated and then an H based controller, for the plant represented by the multiplicative uncertainty and the nominal model, is calculated. The obtained H controller is used to control the LTI systems with varying time delays. Simulation examples are given to illustrate the effectiveness of the proposed method.

Key words: linear time invariant (LTI) systems, mixed sensitivity H, varying time delay, unmodeled uncertainty, H control