Cross-Condition Fault Diagnosis of an Aircraft Environmental Control System (ECS) by Transfer Learning

Abstract

Fault diagnosis models based on machine learning are often subjected to degradation in performance when dealing with data that are differently distributed than the training data. Such an occasion is common in reality because machines usually operate under various conditions. Transfer learning is a solution for the performance degradation of cross-condition fault diagnosis problems. This paper studies how transfer learning algorithms transfer component analysis (TCA) and joint distribution alignment (JDA) improve the cross-condition fault diagnosis accuracy of an aircraft environmental control system (ECS). Both methods work by transforming the source and target domain data into a feature space where their distributions are aligned to allow a uniform classifier to act accurately in both domains. This paper discovered that both TCA and JDA produce significantly more accurate results than traditional methods on target domains with unlabelled ECS data taken at different operating conditions than the source domain. Additionally, when dealing with unlabelled data from unknown conditions bearing a different composition of classes in the target domain, TCA is found to be more robust and accurate, generating an average predictive accuracy of 95.22%, which demonstrates the ability of transfer learning in solving similar problems in the real-world application of fault diagnosis.

A Study on the Effectiveness of Time Series Similarity Measures for the Comparison of Degradation Curves of Similar Engineering Systems

“…The MMD is used, for example, in the transfer learning methods transfer component analysis (TCA), e.g. in [7], joint distribution adaptation (JDA) and related approaches such as balanced distribution adaptation (BDA), e.g. in [7] and [8], and deep adaptation networks (DAN), e.g.…”

“…in [7], joint distribution adaptation (JDA) and related approaches such as balanced distribution adaptation (BDA), e.g. in [7] and [8], and deep adaptation networks (DAN), e.g. in [9].…”

“…The distance function between X i (t) and Y i (t) is integrated. This is done for all time intervals from i = 1 to i = n − 1, and the results are then summed up as can be seen in (7). Instead of linear interpolation, higher-order polynomials can also be used.…”