Fixed Time Disturbance Observer-Based Trajectory Tracking Control of Unmanned Surface Vessel

The high-precision tracking control problem of unmanned surface vehicle with model parameter uncertainty and unknown ocean disturbance is considered. A dynamic surface sliding mode control method for ship trajectory tracking based on fixed time is proposed. Firstly, the model parameter uncertainties and unknown ocean disturbances are regarded as composite disturbances, and a disturbance observer is designed to accurately estimate the disturbances in a fixed time. Secondly, the dynamic surface control technology is used to avoid direct derivation of the desired speed, which simplifies the calculation process. Furthermore, the hyperbolic tangent reaching law is constructed, which effectively weakens the output chattering of the controller. By selecting the appropriate Lyapunov function, it is proved that the control law can ensure that all the error signals of the control closed-loop system are uniformly ultimately bounded. Finally, The ‘LanXin’ USV experimental model is used for simulation research, and the results prove the effectiveness of the proposed control scheme.