Dynamic process monitoring and fault diagnosis with qualitative models

Qualitative Modeling and Interpretation (QMI) and Qmimic are online monitoring and diagnosis systems which use multiple qualitative models of a plant to monitor noisy data streams and rapidly diagnose faults from observed dynamic behavior. Both systems continue monitoring after faults have occurred. QMI simulates normal and faulty plant behavior off-line using purely qualitative QSIM models, and uses plant data to select the correct model, yielding a diagnosis. Qmimic incrementally simulates online qualitative models which describe the current behavior of the plant, using plant data to constrain further predictions and select between the models. Although both systems are based on qualitative models of the plant, Qmimic also incorporates semi-quantitative data (quantitative ranges and bounding envelopes) into the qualitative simulation in order to achieve better predictions. QMI and Qmimic are described and compared in detail, and both are tested on a simulated chemical reactor