Design of linear residual generators for fault detection and isolation in nonlinear systems

A systematic method for the design of disturbance-decoupled linear residual generators for fault detection and isolation (FDI) in nonlinear systems is developed. Necessary and sufficient conditions for the existence of linear residual generators for nonlinear systems are derived. As long as these conditions are satisfied, we obtain explicit design formulas for the residual generator, with eigenvalue assignment. The proposed formulation and results provide a nonlinear generalisation of standard FDI methods for linear systems. The method is applied to three case studies: a bio reactor, a continuous stirred tanked reactor (CSTR) and a process network.