H Bounded Fault Detection Filter

Abstract

A key issue in practical fault detection e lter applications is sensitivity to system disturbances and sensor noise. In this paper, a stabilizing fault detection e lter gain is found that bounds the H1 norm of the transfer matrix from system disturbances and sensor noise to the residual. For multidimensional faults, a residual direction is identie ed that enhances the fault signal-to-noise ratio while maintaining the H1 norm bound. By retaining the faultdetection e lterstructure,thepracticalapplicability oftheproposed approach isthesameasforfaultdetection e lter designs found by conventional eigenvector assignment. In contrast to an unknown input observer approach wherein noise is explicitly decoupled from the fault signal, a noise bounding approach does not impose additional geometric constraints on the e lter structure. This allows a given e lter to isolate more faults, an important feature because in practical applications low-order e lter dynamics are common. Further, the possibility of ill-conditioned e lter eigenvectors, occasionally imposed by geometric constraints, may be reduced.