Analysis of performance criteria in sampled-data fault detection

Sampled-data control systems are widely used in industry. In this paper the problem of fault detection and isolation (FDI) in sampled-data systems is studied. Many existing methods to design a robust sampled-data FDI are based on optimization of a norm based performance index. Our focus in this study is on the selection of the performance index. It is shown that the existing performance indices are not appropriate choices in the sense that they do not satisfy some expected intuitive properties. To resolve this, an alternative performance index is defined after converting the FDI problem to a standard control problem. This performance index is shown to satisfy the expected properties.