Vol 77 No 4 77409

Abstract

This paper focuses on trajectory tracking control problem in unmanned surface vehicles (USVs) operating under complex ocean disturbances. To accurately characterize the marine environment and evaluate control performance under realistic operating conditions, a three-dimensional short-crested irregular wave force model with randomly distributed frequencies and propagation directions is established. This model incorporates stochastic and multidirectional wave loading into the USV dynamics and control framework, providing a more realistic representation of wave disturbances for trajectory tracking analysis. Building upon this disturbance modeling, an adaptive predefined time nonsingular terminal sliding mode controller (adaptive PT-NTSMC) is proposed. First, a novel time-varying function is introduced to construct a variable-gain global sliding mode manifold, based on which a predefined time controller is developed to ensure predefined time convergence. Second, an adaptive law is established to independently estimate the upper bound of external disturbances, thereby reducing the reliance of controller design on prior disturbance-bound information. The global and predefined time stability of the closed-loop system is rigorously verified using Lyapunov theory. Simulation and comparative results under short-crested wave conditions validate the effectiveness and improved performance of the proposed control strategy.