Diagnostic reasoning with fault propagation digraph and sequential testing

When faults in a device occur, the subdevices indicated to be at fault may not be the sources of failure. The ability of a diagnostic system to trace and locate the true sources of failure is therefore very important. This paper presents new algorithms for locating failure sources by using knowledge of device structure and fault propagation paths, and through the use of sequential testing of system subdevices. The inference strategy presented in this paper uses a systematic method of generating subdevices for testing as a way of reducing the candidate space for both single fault and multiple fault situations. In the case of a single failure source, the approach presented will correctly identify the subdevice which is the failure source. In the case of multiple failure sources, a small set of possible failure sources will be identified whose collective failure will explain all the known abnormalities