Curve Path Following Based on Improved Line-of-Sight Algorithm for USV

In this paper, we propose an adaptive forward-looking distance tracking algorithm for unmanned surface vehicle (USV) based on extended state observer (ESO) so as to track the curve path better when sailing at sea. Firstly, the setting waypoints are interpolated to generate the curve path by using the cubic Hermite algorithm. Then, aiming at the problem of large tracking error caused by fixed forward-looking distance in traditional line-of-sight (LOS) guidance algorithm, we introduce a function of cruise speed, cross-tracking error, path curvature and turning radius of the vessel to adjust the forward-looking distance adaptively. In addition, a guiding law is designed to compensate for the navigation error caused by the time-varying sideslip angle, and the angle can be accurately estimated online based on ESO. Finally, the S-plane controller is adopted to control the heading of the vessel. Simulation experiments show that the designed path tracking algorithm can achieve good tracking accuracy.