Online Model-Based Diagnosis of Production Systems

This paper extends model-based diagnosis (MBD) (Reiter 1987; de Kleer & Williams 1987) to systems which convert, move and process material. Examples of such systems are printers, refineries and food processing plants. Such plants present two challenges to model-based diagnosis: (1) the plant may process 100s-1000s of items per minute so retaining full details of behavior of all past objects is impractical, and (2) complex multi-way interactions can occur among components operating on the same object. We address the first challenge by synopsizing past behavior in a data structure of fixed size. We address the second challenge by introducing the notion of interaction fault which represents the situation where a set of components operating on the same object damage the object even though each component alone produces no noticeable damage. Introducing interaction faults is much simpler than introducing fine-grained models of componentobject interactions. We demonstrate the approach on a highly redundant printer.