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

Abstract

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.

Synchronized tracking control for dynamic positioning vessel

“…In marine engineering, terminal sliding mode control is also proposed for applications in DP technology. With this approach, within finite time, the state‐variables converge to the neighborhood of the equilibrium 17 . Thus, in the work in Reference 18, the methodology of terminal sliding mode design is developed for a semi‐submersible platform to achieve the DP mission.…”

“…With this approach, within finite time, the state-variables converge to the neighborhood of the equilibrium. 17 Thus, in the work in Reference 18, the methodology of terminal sliding mode design is developed for a semi-submersible platform to achieve the DP mission. Then, a robust adaptive scheme is utilized to update the control gain and address the effects on disturbances and uncertain dynamics.…”

Event‐triggered disturbance rejection tracking for surface ships under stochastic disturbances and actuator saturation

“…The disturbance attenuations such as the robust $$$ {\mathscr{H}}_{\infty } $$$ control 7 and the sliding mode control 8 counteract time‐varying disturbances robustly by using known or estimated disturbance bounds such that they have the drawback of conservativeness in the presence of time‐varying external disturbances. The disturbance rejection such as the disturbance observer 9 and the extended state observer‐based 10 control achieves the time‐varying external disturbance cancellation by means of on‐line disturbance estimations. Under partially known and slowly‐varying disturbances, a passive nonlinear observer 11 as a disturbance on‐line estimator was designed for the dynamic positioning of marine surface ships, where ocean stochastic disturbances were described by the first‐order Markov stochastic process.…”

A Finite-Time Sliding-Mode Controller Based on the Disturbance Observer and Neural Network for Hysteretic Systems with Application in Piezoelectric Actuators

“…Disturbance observers (DOBs) as tools to improve the accuracy of nonlinear systems have been widely used in robot manipulators [ 32 ], ships [ 33 ], spacecraft [ 34 ], quadrotors [ 35 ], etc. Recently, various DOBs have been developed in enhancing the control accuracy of PEAs.…”