一类伴有部分解耦干扰的非线性系统故障诊断

A finite-frequency domain fault diagnosis scheme based on the H₋/L_∞ unknown input observer (UIO) is proposed for Lipschitz nonlinear system actuator fault detection and sensor fault estimation. First, an augmented system is developed by constructing an augmented state composed of system states and sensor faults. Then, the unknown input disturbances are divided into decoupled disturbances and the disturbances that cannot be decoupled. For the decoupled disturbances, the observer matching condition is used to eliminate them from the estimation error. The L_∞ index is designed to attenuate the influence of disturbances that cannot be decoupled and the finite-frequency domain H₋ index is used to improve the actuator fault detection sensitivity. Moreover, sufficient conditions for the proposed observer are derived and converted into a linear optimization problem constrained by linear matrix inequalities (LMIs). Robust detection of actuator faults and robust estimation of sensor faults are achieved. Finally, the correctness and effectiveness of the developed observer are validated through simulation examples.