Global Fast Terminal Sliding Mode Control for Path Following of Ultra Large Underactuated Ship Based on Predictive Los Guidance

Abstract

This article proposes a new LOS guidance method based on position prediction, which constructs the total path deviation by predicting the future time position of ships. It can solve the problem of overshoot that is prone to occur in the path following process of ultra large underactuated ships. Use global fast terminal sliding mode to design controllers that allow path deviations to converge in finite time. In order to solve the problems of unknown speed, disturbance, and sideslip angle during navigation, a high-order nonlinear observer is designed to estimate the system states, obtaining the velocity values and external disturbances. By estimating the velocity, the ship's sideslip angle during navigation is obtained. So the problem of unknown sideslip angle is solved, and finally, the effectiveness of the proposed algorithm was verified through simulation experiments.

Keywords: Ship path following, Pre-LOS, Global fast terminal sliding mode, High order nonlinear observer, sideslip angle