Method for monitoring a degradation of an on-board device of an aircraft with automatic determination of a decision threshold

• Main Authors: HMAD OUADI, BOULET XAVIER, MASSE JEAN-REMI ANDRE, BEAUSEROY PIERRE JEAN EMILE, GRALL-MAES EDITH
• Format: Patent
• Language: English
• Published: 21.01.2015
• Subjects: CONTROL OR REGULATING SYSTEMS IN GENERAL; CONTROLLING; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS ORELEMENTS; PHYSICS; REGULATING

The invention relates to a method for monitoring a degradation of an on-board device of an aircraft, comprising a step of comparing an abnormality score obtained for a given flight of the aircraft with a decision threshold (S), and a step of emitting an alarm in the event of the decision threshold (S) being exceeded, the decision threshold (S) being automatically determined for a given alarm probability Pa corresponding to the probability that an alarm is emitted during the monitoring method while the on-board device is in good condition, by means of the following steps: a step of calculating a plurality of abnormality scores for a plurality of flights of the aircraft without degradation in such a way as to obtain a distribution of the probability density of the abnormality score, the distribution being specific to the physical nature of the on-board device; a step of adjusting the distribution by a non-parametric estimator of the probability density in such a way as to obtain a continuous adjusted distribution function; a step of calculating a continuous adjusted spread function from the continuous adjusted distribution function; and a step of reading the antecedent of the continuous adjusted spread function for the value 1-Pa, the antecedent corresponding to the decision threshold (S).