Nonlinear fault detection and isolation via unobservability codistribution

This paper deals with fault detection and isolation (FDI) in nonlinear systems using unobservability codistribution. A solution to the problem of fault detection and isolation for nonlinear systems, which is based on the relevant change of coordinate, is characterized in terms of unobservability codistribution. Then a dimensional linear state observer is constructed, according to the new system, to build a residual generation which is available to detect and isolate the occurrence of faults. The above development is illustrated through a real application dealing with the detection and isolation of two failures.