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Mathematical Problems in Engineering
Volume 2015, Article ID 976925, 11 pages
http://dx.doi.org/10.1155/2015/976925
Research Article

Robust Control of Neutral System with Time-Delay for Dynamic Positioning Ships

1College of Automation, Harbin Engineering University, Harbin 150001, China
2The Institute of Automation of Heilongjiang Academy of Science, Harbin 150001, China
3School of Science, Harbin Engineering University, Harbin 150001, China
4College of Mechanics and Electronics Engineering, Harbin Engineering University, Harbin 150001, China

Received 1 June 2014; Revised 14 July 2014; Accepted 16 July 2014

Academic Editor: Yuxin Zhao

Copyright © 2015 Dawei Zhao 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.

Abstract

Due to the input time-delay existing in most thrust systems of the ships, the robust controller is designed for the ship dynamic positioning (DP) system with time-delay. The input delay system is turned to a neutral time-delay system by a state-derivative control law. The less conservative result is derived for the neutral system with state-derivative feedback by the delay-decomposition approach and linear matrix inequality (LMI). Finally, the numerical simulations demonstrate the asymptotic stability and robustness of the controller and verify that the designed DP controller is effective in the varying environment disturbances of wind, waves, and ocean currents.