| Depending on the trend of the fault diagnosis,Case- Based Reasoning, CBR method is applied to diagnosis fault for aircraft pneumatic system and supported in maintenance decision fileds.Based on abundant of repair experience and records that are accumulated in after-service of A320 aircraft, the common fault regular patterns of pneumatic system is summarized.Firstly,according to the characteristic of the fault diagnosis for pneumatic system,a model that accomplishing fault diagnosis based on CBR and RBR is brought forward. The case representation is discussed in detail. Concept view and logical view are established by requirement analysis, and so generated relational case database. The method proposed can represent historical faults and maintenance experience accurately.Secondly,hierarchy retrieval modal was made.By the use of analytic hierarchy process(AHP) method to determine the weights of case feature attribute,the rough filtration strategy of case retrieval is established. In terms of the disadvantage of global similarity utilizing similarity by k-NN algorithm, the dynamic fault ratio was proposed and the reference degree was formed based on it. The proposed method can solve the seasonal characteristics of the pneumatic system and can rise the troubleshooting ratio.Finally,based on the research of fault diagnosis process of aircraft pneumatic system and CBR method introduction earlier suggested,the aircraft pneumatic system fault diagnosis system(PSFDS)is developed.The software has a signifacance to the pneumatic fault diagnosis. |
