Case Based Reasoning For Fault Diagnosis Research Using The Improved Gray Theory

Air transportation is playing an important role in the modern society. With the increasing quantity of aircraft and flight, the tasks of aircraft maintenance are more and more heavy. The maintenance is significant for the aircraft safety. The engine is the heart of aircraft, and it is the key to repair an aircraft. A proper engine fault diagnosis method could guarantee the maintenance personnel to repair correctly and effectively.As one of intelligent diagnostic methods, the development of case-based reasoning is promoting the progress of intelligent diagnostic technology. The case reasoning in the field of fault diagnosis is being applied more and more widely with its original advantages. The principle of case-based reasoning is to match the current problem to the historical case based on its characteristic properties and find similar cases in order to solve current problem.Firstly, state vector of case feature was introduced by studying the basic principle of case-based reasoning, the representation of engine fault cases and feature attribute quantification method. Each case was represented in the form of a vector to realize the transformation of the case from qualitative description to quantitative calculation.Secondly, the research focused on the method of improved gray theory realizing case-based reasoning, including the similarity calculation method of text-based fault describing and the calculation of feature attribute weight and the model of improved grey theory calculated the similarity between cases. The results showed that the improved gray theory to realize the case-based reasoning can achieve the diagnosis of the engine fault with high accuracy and feasibility.Finally, an aircraft engine intelligent fault diagnosis system was developed by using the engine fault history data, which integrated the theoretical research above. The improved gray theory to achieve case-based reasoning can accurately diagnose engine fault and the effectiveness of the system is demonstrated.