Disturbance observer‐based finite‐time control scheme for dynamic positioning of ships subject to thruster faults

• Published in: International journal of robust and nonlinear control Vol. 31; no. 13; pp. 6255 - 6271
• Main Authors: Chen, Haili, Ren, Hongxiang, Gao, Zongjiang, Yu, Feng, Guan, Wei, Wang, Delong
• Format: Journal Article
• Language: English
• Published: Bognor Regis Wiley Subscription Services, Inc 10.09.2021
• Subjects: Convergence; Disturbance observers; dynamic positioning; finite‐time disturbance observer; finite‐time observer‐based thruster fault‐tolerant control scheme; integral nonsingular fast terminal sliding mode control scheme; Marine resources; Marine technology; Robustness; Ships; Sliding mode control
• ISSN: 1049-8923; 1099-1239
• DOI: 10.1002/rnc.5610

Summary The increasing dependence on marine resources has encouraged the rapid development of dynamic positioning (DP) technology in ships and other marine vessels. This study proposes a novel DP scheme for ships subjected to comprehensive disturbances (unknown environmental disturbances and thruster faults). An integral nonsingular fast terminal sliding mode control (INFTSMC) scheme is initially designed without accounting for environmental disturbances. This scheme has a higher convergence rate and robustness against unknown environmental disturbances than the NFTSMC scheme. Furthermore, a new finite‐time disturbance observer is developed to adapt to the changes in the comprehensive disturbances and ensure that the observed errors converge within a small region around the origin in finite time. The INFTSMC scheme is then combined with the finite‐time observer to create a finite‐time observer‐based thruster fault‐tolerant control (FTOAFTC) scheme. Detailed simulation studies and quantitative analyses are carried out on the traditional sliding mode control (SMC), NFTSMC, and FTOAFTC schemes. The FTOAFTC scheme's transient and steady‐state performances, robustness against environmental disturbances, and fault‐tolerance ability are found to be superior to those of the other schemes.