This paper presents an fault detection (FD) method for a class of uncertain nonlinear systems with unmatched nonlinear fault functions and disturbances. A recursive FD observer is designed with predetermined and small output estimation error. The nonlinear observer gain function is achieved by introducing predetermined output estimation accuracy-dependent nonnegative functions. Combining Lyapunov functions, it is shown that the absolute value of the residual signal is equal or lesser than tight threshold before fault occurrence. The FD scheme is proposed following fault detectability analysis, simulation example indicates the validity of the proposed method.

中文翻译：

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基于递归观测器和紧阈值的不确定非线性系统故障检测

本文提出了一类具有不匹配非线性故障函数和扰动的不确定非线性系统的故障检测（FD）方法。递归FD观察器被设计为具有预定且小的输出估计误差。非线性观测器增益函数是通过引入预定的输出估计精度相关非负函数来实现的。结合李雅普诺夫函数，表明残差信号的绝对值等于或小于故障发生前的紧阈值。在故障可检测性分析之后提出了FD方案，仿真实例表明了所提出方法的有效性。