# An Intelligent Bearing Fault Transfer Diagnosis Method Based on Improved Domain Adaption

## TL;DR

This paper introduces a new method for diagnosing bearing faults across different domains by improving feature transfer using advanced domain adaptation techniques.

## Contribution

The novelty lies in combining multi-layer multi-kernel MMD with adversarial domain classification for enhanced cross-domain adaptability.

## Key findings

- The proposed method effectively extracts domain-invariant features.
- It significantly reduces the distribution gap between source and target domains.
- Cross-domain diagnostic performance is notably improved.

## Abstract

Aiming to tackle the challenge of feature transfer in cross-domain fault diagnosis for rolling bearings, an enhanced domain adaptation-based intelligent fault diagnosis method is proposed. This method systematically combines multi-layer multi-core MMD with adversarial domain classification. Specifically, we will extend alignment to multiple network layers, while previous work typically applied MMD to fewer layers or used single core variants. Initially, a one-dimensional convolutional neural network (1D-CNN) is utilized to extract features from both the source and target domains, thereby enhancing the diagnostic model’s cross-domain adaptability through shared feature learning. Subsequently, to address the distribution differences in feature extraction, the multi-layer multi-kernel maximum mean discrepancy (ML-MK MMD) method is employed to quantify the distribution disparity between the source and target domain features, with the objective of extracting domain-invariant features. Moreover, to further mitigate domain shift, a novel loss function is developed by integrating ML-MK MMD with a domain classifier loss, which optimizes the alignment of feature distributions between the two domains. Ultimately, testing on target domain samples demonstrates that the proposed method effectively extracts domain-invariant features, significantly reduces the distribution gap between the source and target domains, and thereby enhances cross-domain diagnostic performance.