Time-varying full-state constrainted USV tracking based on Fixed-time sliding mode control

This paper proposes an adaptive fixed-time control law based on time-varying integral barrier Lyapunov function (TVIBLF) for the trajectory tracking control problem of unmanned surface vehicles (USVs) with time-varying full-state constraints. Traditional barrier functions require error transformation when dealing with time-varying constraints, which have limitations such as strong conservatism and complex stability analysis. Therefore, this article designs a new TVIBLF that utilizes time-varying constraint boundaries and the USV system to construct an error-free transformation constraint mechanism, ensuring that the state is always within the feasible domain. Furthermore, by combining the backstepping method with fixed-time sliding mode control theory, an integral sliding mode surface is introduced to propose sliding surface guarantees trajectory tracking deviations converge to a compact set within bounded time T max , overcoming limitations of asymptotically convergent controllers, compensating for model uncertainties through online approximation using RBFNNs. Finally, simulation experiments verified the effectiveness and robustness of the proposed method under time-varying constraints and unknown disturbances.