METHOD AND DEVICE FOR DIAGNOSING FAULT

PURPOSE: To accurately and speedily diagnose the fault of an object system by deciding whether or not a final diagnostic result obtained by selecting low- order nodes in order on the basis of the path selection coefficients and degrees of conviction of the respective nodes is proper and updating the path selection coefficients of the nodes on the diagnostic path. CONSTITUTION: The inference part 21 of the diagnostic device 2 narrows down the cause of the system fault by sequentially selecting a next diagnostic node by using a degree Lk of learning conviction calculated by a conviction degree correction part 2 while referring to diagnostic trees 11a and 11b of a knowledge base 11. The conviction degree correction part 22 calculates the degree Lk of learning conviction from the degree Pk of conviction calculated by the inference part 21 and a learning coefficient Sk received from a learning coefficient storage part 13 and outputs it to the inference part 21. A learning coefficient update part 23 updates the learning coefficient Sk of the node stored in the learning coefficient storage part 13 on the basis of the diagnostic path stored in a path storage part 12 in the name of a node name and a proper/improper decision on the diagnostic result made by an operator. Then a next fault diagnostis is taken by using the updated learning coefficient.