Abstract: An adaptive trajectory tracking control strategy was proposed to address the problems of speed loss caused by rudder maneuvering and tracking error becoming larger due to steering during the unmanned surface vehicle trajectory tracking. In the guidance loop， the admittance circle radius of the track points was adjusted according to the angle between the track segments based on the adaptive admittance circle strategy，and the adaptive line of sight（LOS）guidance law was designed to improve the tracking accuracy of the unmanned surface vehicle when steering. In the control loop，the decoupling control strategy of heading and speed based on model predictive control（MPC）was proposed，which first considered the coupling term of the heading model and speed model as a time-varying disturbance and proposed a new time delay estimation method，then predicted it by the heading controller， and finally compensated for the time-varying disturbance in the speed controller to reduce the speed loss. After that，the feasibility of the algorithm was verified by the MATLAB simulation platform. The experimental results showed that the proposed adaptive trajectory tracking control strategy had higher tracking accuracy，faster convergence speed，better anti-interference capability，and less energy consumption.

Key words: unmanned surface vehicle, trajectory tracking, adaptive line of sight, model predictive control, time delay estimation