Path Following of Underactuated Unmanned Surface Vehicle Based on Trajectory Linearization Control with Input Saturation and External Disturbances

This paper investigates the path following control problem for underactuated unmanned surface vehicle (USV) in the presence of unmodeled dynamics, external disturbances and input saturation. A novel adaptive robust path following control scheme is proposed by employing trajectory linearization control (TLC) technology and finite-time disturbance observer, which is composed of a concise yaw rate controller and a surge speed controller. The salient features of the proposed scheme include: a path following guidance law is designed to ensure USV effectively converging to and following the desired path; TLC is introduced into the field of USV motion control as new effective technique, and it is the first time used to design path following controller for underactuated USV; a finite-time nonlinear tracking differentiator is constructed not only to avoid the signal jump caused by derivation, but also to filter noise and high frequency interference. A finite-time disturbance observer (FDO) is devised to exactly observe the uncertain dynamics and unknown external disturbances, which improves the tracking accuracy and precise disturbance rejection of the proposed controller; then, an auxiliary dynamic system that is governed by smooth switching function is developed to compensate for the saturation constraint on actuator. Stability analysis verifies that all signals in the closed-loop system are uniformly ultimately bounded. Finally, simulation results and comparisons illustrate the superiority of the proposed control scheme.