Sensor fault detection for diesel engines

This paper deals with the problem of sensor fault detection for diesel engines. We are particularly interested to detect faults affecting the inlet and exhaust pressure sensors. First, this problem is reformulated as actuator fault detection problem by augmenting the system equations by an auxiliary state representing the dynamic behavior of the sensor fault. Then, a nonlinear unknown input observer (NIUO) is used for estimating simultaneously the original states and the sensor fault. The modified mean value theorem (MMVT) is applied to express the nonlinear error dynamics as a convex combination of known matrices with time varying coefficients. Sufficient conditions for the existence of the unknown input observer is presented. The observer gains are obtained by solving the linear matrix inequality (LMI). Performances of the proposed approach are shown through the application to a diesel engine model.