Optimal sensor location in closed-loop control systems for fault detection and isolation

A problem as to where to pick-up the best signal to generate the residual for the purpose of fault detection and isolation (FDI) arises from implementing an observer-based FDI scheme in a closed-loop control system. This paper addresses and proposes a systematic analysis for this issue based on the system sensitivity theory. The results from this study provide a guideline in choosing the optimal location to pick-up signals for residual generation in a closed-loop control system for FDI. The results have been verified by both computer simulation and a real-time implementation on a laboratory-scale electric machine system.