Residual structuration based on a new observer scheme for sensor fault detection and isolation

In observer-based approach for fault detection and isolation, two schemes are generally considered, namely the dedicated observer scheme (DOS) and the generalized observer scheme (GOS). DOS is a bank of observers sensitive to only one fault while GOS is composed of observers sensitive to all faults except one. In this paper a new sensor fault diagnosis approach named Reconstruction Observer Scheme (ROS) is proposed, which does not need any bank of observer, only one observer is used. The proposed method based on reconstruction of variables is used to generate a structured residuals for fault isolation. After the fault detection, the reconstruction is carried of all the variables. Reconstruction of a variable consists on the replacement of this variable to the input of the observer by its estimation. This operation eliminates fault effect when a faulty variable is reconstructed. The proposed approach is illustrated by an academic example.