The Performance of Observer-based Residuals for Detecting Intermittent Faults: The Limitations

In this paper a broad nonlinear system is considered. Attention is focused upon both performance of a high-gain observer-based residual and the investigation of residual effectiveness for detecting faults in actuators/components. Residual performances for different fault positions and various system complexities are compared. Both qualitative and quantitative evidence for selected fault positions indicated the performance and the effectiveness of the residuals decrease by ascending the system complexity. The poor performance of residuals in the more complex system may cause No Fault Found (NFF). The methods may be extended to the more general class of nonlinear systems and different observers. Efficiency of the proposed approach is demonstrated through the intermittent failure case in a vehicle suspension system.