Global finite-time PLOS-OCCs guidance and adaptive integral sliding mode path following control for unmanned surface vehicles with ocean currents and input saturation

This paper studies the problem of finite-time path following for unmanned surface vehicles (USVs) with ocean currents compensation and input saturation, and proposes a finite-time integral sliding mode path following control strategy using a finite-time predictor line-of-sight with ocean currents compensators (FTPLOS-OCCs). In the guidance module, a FTPLOS-OCCs guidance law is presented to eliminate the sideslip angle and unknown ocean currents, compensating for ocean current disturbances at the kinematics level. Then, the adaptive finite-time integral sliding mode control (AFTISMC) laws are developed to achieve path following for USVs in the control module, and the lumped disturbance is solved by combining RBF neural network with adaptive update law, simplifies the complexity of neural network. Meanwhile, a finite-time improved auxiliary dynamic system with nth-order smoothly switching function (FTIADS-nOSSF) is developed to solve the input saturation problem of controller at the dynamic level. Theoretical analysis indicates that the system is global finite-time uniformly ultimately bounded, and path following errors converge to a small neighborhood of the origin within a finite time. Finally, the effectiveness of the control scheme is verified through comparative simulations.