Construction of causality diagram model for diagnostics

Causality diagram is one of the most effective theoretical models for uncertainty knowledge expression and reasoning. In order to realize the computer-aided construction of the causality diagram for diagnostics, this paper proposes a simple, yet comprehensive representation model to organize the failure knowledge more systematically and completely. This method defines the failure modes as the inherent properties of the physical entities at different hierarchical levels, and employs the polychromatic sets theory to represent the failure modes in terms of their interrelationships and their relations to the physical system. Then, the infrastructure of the diagnostic causality diagram (DCD) is constructed in a deductive manner by using the iterative search process operated on the reasoning matrices of the polychromatic sets. A case study is used to illustrate the feasibility of the proposed method. The research shows that the polychromatic sets approach to the DCD construction has formed mathematical foundation and can be readily implemented in computer.