Robust control of networked control systems with randomly varying time-delays based on adaptive Smith predictor


  • Xuan-Kien Dang Department of Electrical and Electronic Engineering, Ho Chi Minh City University of Transport, Vietnam
  • Van-Thu Nguyen Department of Maritime Engineering, Ho Chi Minh City University of Transport, Vietnam
  • Xuan-Phuong Nguyen Department of Maritime Engineering, Ho Chi Minh City University of Transport, Vietnam


networked control system, neural networks, adaptive Smith predictor, time-delay estimation, robust controller, Linear Matrix Inequality


In this paper, we deal with the robust control of network induced delay and randomly varying time-delay (RVTD) controlled plant in networked control systems (NCS).  The control problem of NCS becomes more challenging to attain the robust stability when time-delay appears in form of a time-varying signal in the closed loop of NCS.  These in turn make the conventional control methods, e.g., normal mathematical model of Smith predictor, more complicated to meet the quality requirements of NCS.  To overcome these inherent challenges, we essentially analyzed the existing techniques, and then propose a novel adaptive Smith predictor to efficiently reduce the effect of time-delays for high efficient and accurate control.  Hence, the delay-dependent NCS becomes the delay-independent NCS, we proposed a necessary and sufficient conditions for the robust stability and performance of NCS in general formulation.  By using the H∞ loop-shaping - McFarlane and Glover controller design method based on co-prime factor robustness and Linear Matrix Inequality (LMI), a robust controller has been suggested.  The simulation results via TrueTime Beta2.0 platform demonstrate the usefulness and effectiveness of the proposed method.


Agarwal, M., & Canudas, C. (1987). Online estimation of time delay and continuous time process parameters. International Journal of Control, 46(1), 295-311. DOI: 10.1080/00207178708933899

Anton, C., Dan, H. S., & Martin, O. L. (2009). TrueTime 2.0 beta 1- Reference Manual, 1st ed. Sweden. Department of Automatic Control: Lund University, Sweden.

Astrom, K. J., Hang, C. C., & Lim, B. C. (2003). A new Smith predictor for controlling a process with an integrator and long dead-time. ISA Transactions. The Instrumentation, Systems, and Automation Society, 42(1), 101-110.

Bahill, A. T. (1983). A simple adaptive Smith predictor for controlling time-delay systems. IEEE. Control System Magazine, 3(2), 16-22. DOI: 10.1109/MCS.1983.1104748

Chen, C. H., Lin, C. L., & Hwang, T. S. (2007). Stability of networked control systems with time-varying delays. IEEE. Communications Letters, 11(3), 270-271.

Chunmao, L., & Jian, X. (2006,October). Adaptive delay estimation and control of networked control systems. International Symposium on Communications and Information Technologies (ISCIT06), Bangkok, Thailand.

Cloosterman, M. B. G., Van de Wouw, N., Heemels, W. P. M. H., & Nijmeijer, H. (2006). Robust stability of networked control systems with time-varying network-induced delays. Proceedings of the 45th IEEE Conference on Decision and Control, San Diego, USA.

Cuenca, A., Salt, J., Casanova, V., & Piz, R. (2010). An approach based on an adaptive multi-rate smith predictor and gain scheduling for a net-worked control system: Implementation over Profibus-DP. International Journal of Control Automation and Systems, 8(2), 473-481. DOI: 10.1007/s12555-010-0237-1

Dang, X. K., Guan, Z. H., & Tran, H. D. (2012). Joint smith predictor and neural network estimation scheme for compensating randomly varying time-delay in networked control system. Proceedings of the 24th Chinese Control and Decision Conference, Tai Yuan, China.

Dang, X. K., Guan, Z. H., Tran, H. D., & Li, T. (2011). Fuzzy Adaptive Control of networked control system with unknown time-delay. Proceedings of the 30th Chinese Control Conference, Yantai, China.

Du, W., Du, F., & Lei, Z. (2009). Networked control systems with nonlinear control and novel smith predictor. Proceedings of Asia-Pacific Conference on Information Processing, Shenzhen, China.

DOI: 10.1109/APCIP.2009.26

Feng, D. M., Pan, F., & Han, R. C. (2002). Improved self-adaptive Smith predictive control scheme for time-delay system. Proceedings of the First International Conference on Machine Learning and Cybernetics, Beijing, China, Nov., pp. 463-466.

Ge, S. S., Hong, F., & Lee, T. H. (2003). Adaptive neural network control of nonlinear systems with unknown time delays. IEEE Transactions on Automatic Control, 48(11), 2004-2010.

DOI: 10.1109/TAC.2003.819287

Glover, K., Sefton, J., & McFarlane, D. C. (1992). A tutorial on loop-shaping using H-infinity robust stabilization. Transactions of the Institute of Measurement and Control, 14(3), 157-168.

DOI: 10.1177/014233129201400306

Huang, Y. J., Kuo, T. C., & Tseng, H. Y. (2007). Fuzzy estimator design for the control systems with unknown time-delay. Proceedings of the World Congress on Engineering, Vol I, C-26. WCE 2007, July 2-4, 2007, London, U.K.

Ioan, D., Ioana, M., & Raluca, M. (2005). On the robustness of modified Smith predictor controller for time delay processes. International Journal of Control Engineering and Applied Informatics, 7(3), 9-14.

Jiang, S., & Fang, H.- J. (2013). H∞ static output feedback control for non-linear networked control systems with time delays and packet dropouts. ISA Transactions, 52(2), 215-222. DOI:10.1016/j.isatra.2012.10.006

Lai, C. L., & Hsu, P. L. (2010). Design the remote control system with the time-delay estimator and the Bolea, Y., Puig, V., & Blesa, J. (2011). Gain scheduled Smith proportional integral derivative controllers for linear parameter varying first-order plus time-varying delay systems. IET Control Theory and Applications, 5(18), 2142-2155. DOI: 10.1049/iet-cta.2010.0088

McFarlane, D., & Glover, K. (1990).Robust controller design using normalized co-prime factor plant description. Lecture notes in control and information Science. Berlin, Germany: Springer-Verlag.

Meng, D., Jia, Y., Du, J., & Yu, F. (2010). Learning control for time-delay systems with iteration-varying uncertainty: a Smith predictor-based approach. IET Control Theory and Applications, 4(12), 2707-2718.

DOI: 10.1049/iet-cta.2009.0408

Mu, J., Liu, G. P. & Rees, D. (2005). Design of Robust Networked Predictive Control Systems. Proceedings 2005 American Control Conference, Portland, USA, pp. 638-643.

Notari, K., & Ohnishi, K. (2008). A design method of communication disturbance observer for time-delay compensation, taking the dynamic property of network disturbance into account. IEEE Transactions on Industrial Electronics, 55(5), 2152-2168. DOI: 10.1109/TIE.2008.918635

Pan, I., Das, S., & Gupta, A. (2011). Tuning of an optimal fuzzy PID controller with stochastic algorithms for networked control systems with random time delay. ISA Transactions, 50(1), 28-36. DOI: 10.1016/j.isatra.2010.10.005

Peng, C., Tian, Y. C., & Tade, M. O. (2007). State feedback controller design of networked control systems with interval time-varying delay and nonlinearity. International Journal of Robust Nonlinear Control, 18(12), 1285-1301. DOI: 10.1002/rnc.1278

Shaltaf, S. J. & Mohammad, A. A. (2009). Neural Networks Based Time-Delay Estimation using DCT Coefficients. American Journal of Applied Sciences, 6(4), 703-708.

Shaltaf, S. J. (2007). Neuro-fuzzy based time-delay estimation using DCT coefficients. ISA. Transactions, 46(1), 21-30. DOI: 10.1016/j.isatra.2006.02.002

Shaltaf, S., & Abdallah, M. (2000). An enhanced technique for online discrete cosine transform based-time varying delay estimation. Circuits, Systems and Signal Processing, 19(6), 501-515. DOI: 10.1007/BF01271285

Tran, H.-D., Guan, Dang, X.-K., Cheng, X-M., & Yuan, F.-S. (2013). A normalized PID controller in networked control systems with varying time delays. ISA Transactions, 52(5), 592-599. DOI: 10.1016/j.isatra.2013.05.005

Turner, M. C., & Bates, D. G. (2007). Mathematical Methods for Robust and Nonlinear Control. Lecture Notes in Control and Information Sciences, EPSRC Summer School. New York, USA: Springer.

Vidyasagar, M. (1985). Control system synthesis: A Factorization Approach. Cambridge, Mass., USA: MIT Press.

Zhang, W.-A., & Yu, L. (2010). A robust control approach to stabilization of networked control systems with short time-varying delays. International Journal of Acta Automatica Sinica, 36(1), 87-91. DOI: 10.1016/S1874-1029(09)60006-9

Zhou, K., Doyle, J., & Glover, K. (1995). Robust and optimal control. (1st ed.). Prentice Hall.




How to Cite

Xuan-Kien Dang, Van-Thu Nguyen, & Xuan-Phuong Nguyen. (2023). Robust control of networked control systems with randomly varying time-delays based on adaptive Smith predictor. Journal of Current Science and Technology, 5(2), 175–186. Retrieved from



Research Article