Fault diagnosis

摘要

The invention relates to status estimation of an entity (150) having a plurality of components (c 1 , ..., c n ), which each is assumed to be in a fault-free mode, or in exactly one of at least one fault mode. First and second listings (D; E) of diagnostic expressions (D 1 , ..., D n ; E 1 ; ..., E m ) are received and stored in a first storage area (120). An empty listing of enhanced diagnostic expressions (Q) is created by clearing any contents of a second storage area (130). Thereafter, for each combination of diagnostic expressions (D i , E j ) in the first and second listings (D; E), a current joint diagnostic expression (Q new ) is generated representing a conjunction of a first diagnostic expression (D i ) from the first listing (D) and a second diagnostic expression (E j ) from the second listing (E). The current joint diagnostic expression (O new ) is compared with each diagnostic expression in the listing of enhanced diagnostic expressions (Q) stored in the second storage area (130), and the expression (O new ) is discarded if: there exists a previous expression (Q k ) in the listing of enhanced diagnostic expressions (Q), and the current joint diagnostic expression (Q new ) implies the previous expression (Q k ); there exists a first diagnostic expression (D k ) in the first listing (D), the first diagnostic expression (D k ) having not yet been included in a joint diagnostic expression and the current joint diagnostic expression (Q new ) implies the first diagnostic expression (D k ); or there exists a second diagnostic expression (E k ) in the second listing (E), the second diagnostic expression (E k ) having not yet been included in a joint diagnostic expression and the current joint diagnostic expression (Q new ) implies the second diagnostic expression (E k ). Any other joint diagnostic expressions (Q new ) are stored in the second storage area (130) as additions to the listing of enhanced diagnostic expressions (Q). A status report is generated (R[Q]) based on the listing of enhanced diagnostic expressions (Q) after having tested all the combinations of diagnostic expressions (D i , E j )