Unknown Input High Gain Observer for Fault Detection and Isolation of Uncertain Systems

An unknown input high gain observer (UIHGO) based component fault detection and isolation (FDI) technique is presented. First, a reduced order UIHGO is derived for a linear system whose parameters are uncertain to some extent. The observer gain is determined by solving the well-known algebraic Riccati equation (ARE). Then, using a bank of such observers, a FDI algorithm is devised to detect and isolate the component fault (i.e., parametric fault) of an uncertain system. The FDI algorithm consists of two steps. In the first step, the detection of fault and the isolation of faulty region are accomplished and in the next step, the faulty parameter is isolated from the faulty region. Effectiveness of the proposed observer as well as the FDI technique is shown with the help of a numerical example.