This paper investigates the control issue of the trajectory tracking of vertical take-off and landing (VTOL) unmanned aerial vehicles (UAVs) in the presence of partial propeller fault and external disturbance. In particular, a robust passive fault-tolerant control strategy is proposed by introducing a first-order filter based dynamics estimator. First, a bounded force command is exploited by employing a new smooth saturation function in the output of the estimator. A sufficient condition in terms of a specified parameter selection criteria is provided to ensure the non-singularity extraction of the command attitude. Then, a torque command is applied to the attitude loop tracking. Since there is merely one filter parameter involved in the dynamics estimator, the practical implementation and parameter tuning can be significantly simplified. Stability analysis indicates that the proposed control strategy guarantees the semi-globally ultimately bounded tracking of VTOL UAVs subject to partial propeller fault and external disturbance. Simulation and experiment results with comparison examples are performed to validate the effectiveness of the proposed strategy. Experimental results show that the proposed strategy achieves the trajectory tracking with a good performance (mean deviation 0.0074 m and standard deviation 0.1202 m) in the presence of 35$\%$ propeller fault and 4 m/s persistent wind disturbance.

本文研究了在存在部分螺旋桨故障和外部干扰的情况下垂直起降（VTOL）无人机（UAV）轨迹跟踪的控制问题。特别是，通过引入基于一阶滤波器的动态估计器，提出了一种鲁棒的被动容错控制策略。首先，通过在估计器的输出中采用新的平滑饱和函数来利用有界力命令。提供了在指定参数选择标准方面的充分条件，以保证指挥姿态的非奇异性提取。然后，将扭矩命令应用于姿态环跟踪。由于动态估计器中只涉及一个滤波器参数，因此可以显着简化实际实现和参数调整。稳定性分析表明，所提出的控制策略保证了受到部分螺旋桨故障和外部干扰的 VTOL 无人机的半全局最终有界跟踪。仿真和实验结果与对比示例进行验证，以验证所提出的策略的有效性。实验结果表明，所提出的策略实现了轨迹跟踪性能良好（平均偏差 0.0074 m 和标准偏差 0.1202 m）在 35$\%$ 螺旋桨故障和 4 m/s 持续风扰动。