An adaptive error constraint line-of-sight guidance and finite-time backstepping control for unmanned surface vehicles

Abstract

This paper presents a finite-time path following control approach with an adaptive error constraint line-of-sight guidance for marine unmanned surface vehicles (USVs). The proposed guidance and control strategy is capable of keeping the cross-tracking error within the constraint range while the USV follows a desired curved path, and it can guarantee the tracking errors converge in finite time for an underactuated USV with unknown disturbances. Specifically, an adaptive error constraint line-of-sight guidance law is originally proposed to calculate the desired course angle and realize cross-tracking error constraint by combining the control Lyapunov function and adaptive sideslip estimator. Furthermore, a finite-time backstepping control method by using a new virtual control signal and modified tracking error compensation signals is applied to control an underactuated USV convergence to the desired course angle. Then, a finite time surge control law with a modified tracking error compensation dynamic is designed to achieve surge velocity tracking. The proposed finite-time control laws have better transient and steady-state performance, and simplify the design of the controller by not relying on interference observers. Case studies using a physics-based model are made to support the theoretical results.