Underwater gliders are increasingly deployed in challenging missions - such as hurricane-season observations and long-endurance environmental monitoring - where strong currents and turbulence pose significant risks to navigation safety. To address these practical challenges, this paper presents a fixed-time prescribed performance control scheme for the 3D path following of underwater gliders subject to model uncertainties and environmental disturbances. The primary contribution is the integration of a finite-time performance function within a fixed-time control framework. This synthesis ensures that the tracking errors are constrained within prescribed performance bounds and converge to a compact set within a fixed time, independent of initial conditions. A second key contribution is the development of a fixed-time sliding mode disturbance observer that provides accurate finite-time estimation of lumped disturbances, enhancing the system's robustness. Integrated with an iLOS guidance law, the proposed controller enables precise and safe waypoint following. Numerical simulations demonstrate that the proposed method outperforms conventional sliding mode and prescribed performance controllers in tracking accuracy, convergence speed, and control effort smoothness, validating its efficacy for robust underwater navigation.

翻译：水下滑翔机正日益部署于具有挑战性的任务中——例如飓风季节观测和长航时环境监测——其中强洋流和湍流对航行安全构成显著风险。为应对这些实际挑战，本文针对受模型不确定性和环境扰动影响的水下滑翔机三维路径跟踪问题，提出了一种固定时间预设性能控制方案。主要贡献在于将有限时间性能函数集成到固定时间控制框架中。该综合方法确保跟踪误差被约束在预设性能边界内，并在与初始条件无关的固定时间内收敛至一个紧集。第二个关键贡献是开发了一种固定时间滑模扰动观测器，该观测器能够对集总扰动提供精确的有限时间估计，从而增强了系统的鲁棒性。所提出的控制器与iLOS制导律相结合，实现了精确且安全的航点跟踪。数值仿真表明，所提方法在跟踪精度、收敛速度和控制量平滑性方面均优于传统滑模控制器和预设性能控制器，验证了其在鲁棒水下导航中的有效性。