IFRN: Insensitive feature removal network for zero-shot mechanical fault diagnosis across fault severity

Zero-shot learning is a promising technique for diagnosing mechanical faults in complex and uncertain environments. However, when diagnosing mechanical faults across different severities using zero-shot learning, the impact of insensitive features should be minimized due to the susceptibility of zero-shot prototypes and the vulnerability of vibration signals. To accomplish this, an Insensitive Feature Removal Network (IFRN) with an entire attention mechanism (EAM) module and a denoise autoencoder module is proposed to remove insensitive features hierarchically by dividing them into two categories: common insensitive features (CIF) and private insensitive features (PIF), each with different properties depending on their corresponding sub-labels presence in mechanical faults. Concretely, EAM removes insensitive features that the classifier cannot differentiate with the help of the entire attention weight comparison by attention generation, attention comparison, and attention limitation parts. Then, the denoise autoencoder module with long short memory term (LSTM) is utilized to remove the insensitive features that are not completely removed, especially for the insensitive features that independently arise. The IFRN's effectiveness is demonstrated through comparative experiments and ablation studies using the Case Western Reserve University (CWRU) dataset, where the experimental result shows that IFRN outperforms conventional zero-shot learning methods. Furthermore, an analysis with prototype distance and sample aggregation is presented to further justify the effectiveness of the proposed method in reducing the prototype shift and improving classification accuracy by removing insensitive features.