Fault Detection and Isolation Method Based on H−/ H ∞ Unknown Input Observer Design in Finite Frequency Domain.

This paper proposes an actuator fault detection and isolation strategy based on a bank of unknown input observers with finite frequency specifications. In order to deal with actuator fault diagnosis problem, a bank of H₋/ H _∞ unknown input observers are designed to generate residuals, which are insensitive to the corresponding faults but sensitive to the other actuators faults, and meanwhile robust against the unknown disturbances. In this paper, the actuator faults and unknown disturbances are considered to belong to finite frequency domains, and two finite frequency performance indices are used to measure the fault sensitivity and the disturbance robustness of the residuals. Furthermore, some parameters for extra design of freedom are introduced in the H₋/ H _∞ unknown input observers design. Based on the generalised Kalman-Yakubovich-Popov (GKYP) lemma, the design conditions of the H₋/ H _∞ unknown input observer are derived and formulated as linear matrix inequalities (LMIs). Finally, a VTOL aircraft model is used to demonstrate the performance of the proposed fault diagnosis scheme. [ABSTRACT FROM AUTHOR]