Adaptive observer based fault diagnosis applied to differential-algebraic systems*

Some engineering systems are naturally described by differential-algebraic equations (DAE), whereas it may be difficult or impossible to model them with ordinary differential equations (ODE). This paper proposes an approach to fault diagnosis for systems described by DAEs. Through a particular discretization method and under realistic assumptions, the considered continuous time DAE model is transformed to an explicit state space model in discrete time. An adaptive observer is then applied to the discretized system for monitoring faults possibly affecting the system and represented by changes in model parameters. As an illustrative example, the diagnosis of faults in a heat exchanger modeled by nonlinear DAEs is studied by numerical simulations.