Active domain adaptation method for label expansion problem

Over the past few years, cross-domain fault detection methods based on unsupervised domain adaptation (UDA) have gradually matured. However, existing methods usually assume that the source and target domains have the same label domain space, but ignore the problem of label expansion in the target domain. The source domain of such problems lacks transferable knowledge of newly added health categories, so the domain invariant features extracted by the UDA model only have a large correlation with the source domain health categories, but lack the key features to distinguish the newly added health categories. We found that most of the diagnostic results of this type of samples are distributed at the decision boundary of the source domain health category, and this special distribution means that the newly added health category samples have a high amount of information. Therefore, this paper considers using active learning to select samples of newly added health categories in the target domain to assist model training, and proposes an active domain adaptation intelligent fault detection framework LDE-ADA to deal with the label expansion problem. Finally, on the rotating machinery dataset, the analysis and comparison are carried out through six transfer tasks. The results show that when there is one new health category, the accuracy of LDE-ADA will increase by about 9.39% in the case of labeling three samples per round and training for 20 rounds. Experiments show that this method is an effective method to deal with the label expansion problem.