All linear methods are equal-and extendible to (some) nonlinearities

Several linear methods of residual generation for fault detection and diagnosis are reviewed. The parity relation approach is introduced in some detail, for both additive and parametric faults. The Chow-Willsky scheme, various diagnostic observers and principal component analysis are compared to the additive version. The 'local approach' and the least-squares estimation of parameter changes are shown to be related to the parametric variant. Nonlinear extensions are demonstrated for all the techniques under additive faults. Copyright (C) 2002 John Wiley Sons, Ltd.