Ship trajectory tracking control based on adaptive fast non-singular integral terminal sliding mode

Aiming at the problems of slow error convergence rate and external unknown disturbances in trajectory tracking control of underactuated ships, an adaptive fast non-singular integral terminal sliding mode (AFNITSM) trajectory tracking control scheme is designed. By designing fast non-singular integral terminal sliding mode surface, the error convergence rate is accelerated and singularities are avoided. In the paper, the controller will be designed using the sliding mode control method, the “differential explosion” problem will be solved using the dynamic surface technique, and adaptive laws will be used to approximate the upper bound of the unknown disturbances in order to improve the control accuracy. Finally, rigorous theoretical analysis will be carried out by Lyapunov’s method to obtain all signals of the closed-loop system are bounded and the tracking errors are made to converge to the bounded interval. Simulation results show that the control scheme proposed in this paper can enable the underactuated ship to track the desired trajectory, and errors converge faster compared with the traditional control scheme, and also has satisfactory robustness in the face of external unknown time-varying disturbances. The study can provide an effective reference for the trajectory tracking control of ships, which is of certain theoretical significance. •An adaptive fast non-singular integral terminal sliding mode control scheme is designed for the slow convergence rate of sliding mode control and the singularity problem. With this scheme, ship can realize the fast tracking of the desired trajectory. The scheme can effectively accelerate the convergence rate of the error and avoid the appearance of singular points.•In the design of the controller, the DSC technique will be combined to solve the “differential explosion” problem.•The adaptive technique will be used to estimate the upper bound of the unknown external disturbances, and the hyperbolic tangent function will be used to eliminate the chattering instead of the traditional sign function.