Semi-qualitative fault diagnosis method based on modal interval analysis

To improve the anti-jamming ability and reliability of fault diagnosis, the semi-qualitative fault diagnosis method which combines the Modal Interval Analysis (MIA) and Analytical Redundancy Relations (ARRs) together has been proposed. The exact interval envelopes for the system have been obtained by using MIA. The fault detection method using interval envelopes can improve the anti-jamming ability of fault detection. The Diagnostic Bond Graph (DBG) model has been constructed by introducing observed signal and virtual sensors into bond graph model of the system. Then the system's ARRs can be generated using the DBG model. The method to build fault signature matrix by incorporating with the causality of DBG and the tendency analysis with the residuals of ARRs has been established. This can improve the accuracy of fault isolation. Through the practical analysis of a five-tank system' s fault diagnosis, the validity has been verified.