Sideslip-restrained adaptive fuzzy path following control for an underactuated unmanned surface vehicle with input saturation

Sideslip during path following can deteriorate the heading accuracy and navigation safety of an underactuated unmanned surface vehicle (USV). Moreover, actuator input saturation further weakens sideslip suppression performance and system stability, which constitutes a critical challenge for USV motion control. This paper proposes a sideslip compensation adaptive fuzzy path following control scheme for the underactuated USV subject to input saturation and model uncertainties. Firstly, a speed-regulator-based kinematics controller is proposed to guarantee convergence of the position error and attenuate the sideslip angle via weighted Lagrangian constrained optimization. Secondly, to counteract input saturation induced by large-curvature turning and dynamic speed transitions, a saturation compensator is designed via two dynamic state variables. Subsequently, an adaptive fuzzy kinetics controller is developed, which is independent of the inherent nonlinear hydrodynamic characteristics of the USV, to guarantee semi-global uniform ultimate boundedness of the closed-loop system. Finally, hardware-in-the-loop experimental results demonstrate that the proposed approach can reduce the sideslip angle and achieve reliable path following under input saturation constraints.