Optimal auxiliary input for fault detection of systems with model uncertainty

Introduction of an auxiliary input is known to be useful to detect the system fault quickly without affecting the original system behavior in normal mode. Such an auxiliary input is designed to enlarge the distance measured by the Kullback discrimination information measure between the system models corresponding to the normal and the fault modes. However, in practice, the designer hardly knows the exact models. Hence, the optimal auxiliary input should be designed for the case of the system models with uncertainty. Here, the auxiliary input is designed to maximize the distance for the worst combination of system models. Numerical simulation results indicate the applicability of the proposed auxiliary input in fault detection.