Robust fault detection filter design

Detection filters form a class of linear observers that produce residuals with known and fixed directional characteristics in response to a set of design fault directions. In practical applications, reliable fault isolation takes place only when the detection space structure is insensitive to system parameter variations. A left-eigenvector assignment approach is developed that allows for the application of existing results relating supremal controllability subspaces and ill-conditioned eigenvectors. Modifications to the detection filter structure that yield improved eigenvector conditioning and sensitivity to system parameter variations are applied to an aircraft accelerometer fault detection filter.