Fixed-time adaptive path-following control of autonomous surface vehicles with asymmetric output performance and feasibility constraints

This paper proposes a fixed-time adaptive path-following control scheme for autonomous surface vehicles (ASVs) to address accuracy and safety considerations in actual navigation practice. The proposed scheme is designed to effectively follow a reference path while satisfying output performance and feasibility constraints during navigation. For the output constraint problem, a modified version of the universal barrier Lyapunov function is used for the analysis of path-dependent constraint requirements. Additionally, a new type of path-dependent constraint function is proposed that depends on the path parameters rather than directly on the time variables. A new adaptive backstepping method is also devised to address the problem of fixed-time convergence, as well as the 'complexity explosion' in the controller design process, and the unknown dynamics of the model. The study shows that, under this control scheme, the ASV's position and heading errors can converge to a set near the equilibrium point at a fixed time convergence rate, while always satisfying the path-dependent constraints. Simulation and experimental studies further validate the effectiveness of the proposed scheme.