Global fast terminal sliding mode control for path following of ultra large underactuated ship based on predictive LOS guidance

This study proposes a new line-of-sight guidance method based on position prediction that constructs the total path deviation by predicting the future time position of ships. This method can solve the problem of overshoot, which is prone to occur in the path following process of ultra large underactuated ships. A global fast terminal sliding mode method is used to design controllers that allow path deviations to converge in a finite time. To solve the problems of unknown velocity, disturbances, and sideslip angle during navigation, a high-order nonlinear observer is designed to estimate the system states and obtain the velocity values and external disturbances. The sideslip angle of the ship during navigation is obtained by estimating its velocity. Therefore, the problem of an unknown sideslip angle is solved, and the effectiveness of the proposed algorithm is verified through simulation experiments.