针对执行器故障和未知环境扰动下的多无人艇协同包围控制问题，提出了一种基于扰动观测器的固定时间滑模容错控制方法。该方法基于分层控制思想，将协同包围系统解耦为制导层与控制层。首先，在制导层设计了一种结合漂角观测器的固定时间分布式协同控制律，以实现无人艇等距旋转包围目标；其次，在控制层将执行器故障视为该层受到的扰动，引入固定时间扰动观测器，对执行器故障和未知环境引起的非线性集总扰动进行在线观测，并设计了固定时间滑模控制器对其进行补偿，在保证动力学误差快速收敛的同时平滑控制输出；最后，基于Lyapunov函数证明了闭环控制系统的稳定性，并通过三艘无人艇的对比仿真，验证了所提方法能够有效减轻执行器故障对协同包围任务的不利影响。

A fixed-time sliding mode fault-tolerant control strategy based on a disturbance observer is proposed for the cooperative encirclement control of multiple unmanned surface vehicles (USVs) with actuator faults and unknown environmental disturbances. The method is grounded in the hierarchical control concept, where the cooperative encirclement system is decoupled into a guidance layer and a control layer. Firstly, in the guidance layer, a fixed-time distributed cooperative control law combined with a sideslip angle observer (SO) is designed to achieve equidistant rotation around the target. Secondly, in the control layer, actuator faults are treated as disturbances affecting the layer, and a fixed-time disturbance observer (FxDO) is introduced to observe the nonlinear lumped disturbances caused by actuator faults and unknown environmental factors in real-time. A fixed-time sliding mode controller (FxSMC) is then designed to compensate for these disturbances, ensuring fast convergence of dynamic errors while smoothing the control output. Finally, the stability of the closed-loop control system is proven using the Lyapunov function, and the effectiveness of the proposed method in mitigating the adverse effects of actuator faults on the cooperative encirclement task is validated through a comparative simulation involving three USVs.