Aiding the operator during novel fault diagnosis

The design and philosophy are presented for an intelligent aid for a human operator who must diagnose a novel fault in a physical system. A novel failure is defined as one that the operator has not experienced in either real system operation or training. Because the fault is novel, the human must reason using causal knowledge. The aid contains unique features that support such reasoning. One of these is a qualitative, component-level model of the physical system. The model can reflect the operator´s hypothesis when it is requested. Both the aid and the human are able to reason causally about the system in a cooperative search for a diagnosis