Robust FDI

Djeziri, M. A., Ould Bouamama, B., Merzouki, R. (2009). Modelling and robust FDI of steam generator using uncertain bondgraph model. Journal of Process Control, 19, 149-162. 

D. Henry, A. Zolghari. (2006). Norm-based design of robust FDI schemes for uncertain systems under feedback control comparison of two approaches . Control Engineering Practice 14, 1081-1097. 

As fault indicators should be sensitive to real faults but insensitive to parameter uncertainties, adaptive system mode dependent thresholds are needed for FDI in hybrid systems robust with regard to parameter uncertainties. Chapter 5 demonstrates that incremental bond graph can serve this purpose for switched LTI systems. To that end some basics of incremental bond graphs are recalled. It is shown how parameter sensitivities of ARRs and ARR thresholds can be obtained. A small example illustrates the approach. 

As to FDI robust with regard to parameter uncertainties, an approach based on so-called uncertain bond graphs in linear fractional transformation form (LFT) has been reported in the literature [8-10] for time-continuous models. In an uncertain bond graph, bonds carry power variables uncertain with regard to parameter variations... 

Moreover, LFT bond graphs can also support robust fault detection and isolation (FDI) of systems with uncertain parameters. The decomposition of bond graph elements leads to a derivation of analytical redundancy relations (ARRs) composed of a nominal part representing their residuals and an uncertain part due to parameter... 

The proposed application shows the robustness of an FDI algorithm on mecha-tronic systems. Indeed, simulation and experimental results show that the algorithm is robust to false alarms, because residues remain inside the thresholds when the system is in normal operation. The performance of the algorithm against the non-detections and delays in fault detection is controlled by estimation of the fault detectable values. 

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