This study proposes a k-nearest neighbor method that integrates distribution discrepancy and differential feature importance for accurate rolling bearing fault diagnosis.
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Method Article
This study proposes a k-nearest neighbor method that integrates distribution discrepancy and differential feature importance for accurate rolling bearing fault diagnosis.
Rolling bearings are among the most vulnerable components in various types of rotary machinery, and accurate fault detection and localization are essential. When a rolling bearing fails, the signal is non-stationary, and the energy distribution of the vibration signal varies depending on the fault location. In traditional k-nearest neighbor (KNN) fault diagnosis algorithms, Euclidean distance is primarily used to measure the distance between sample points, which is not effective at capturing similarity across different spatial distributions. Moreover, these algorithms assume equal feature importance, which does not reflect the actual characteristics of fault vibration signals. This study proposes a KNN-based rolling bearing fault diagnosis method that incorporates distribution discrepancy and differential feature importance. First, vibration signals are decomposed using three-level wavelet packet decomposition, and the energy of each node at the third level is used as the fault feature. Then, the mean impact value (MIV) algorithm is used to determine the relative importance of each feature, and the Earth mover’s distance (EMD) is applied to measure differences between spatial distributions. By integrating Euclidean distance with MIV and EMD and applying the KNN majority voting rule, fault diagnosis is performed. The experimental results indicate that this method achieves a diagnostic accuracy of 99.43%, representing a 5.97% improvement compared to traditional KNN methods. The proposed method demonstrates accurate and effective fault diagnosis performance on the rolling bearing datasets used in this study.
With the progress of technology, rotary machinery is increasingly developing toward integration, large-scale systems, high speed, and intelligent operation1. Among various types of rotary electrical machinery, rolling bearing components are the most vulnerable and commonly damaged parts. They offer advantages such as easy start-up, low friction, simple lubrication, and convenient replacement, and are widely used in precision instruments, aerospace, automobiles, machine tools, robots, and other fields. According to relevant statistical data on rotating machinery failures, abnormal vibration faults account for 70%, and 30% of these vibration faul....
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This study did not involve human participants or animal subjects; therefore, ethical approval and informed consent were not required. The proposed method was implemented using MATLAB R2014b. The following toolboxes were used: Wavelet Toolbox for wavelet packet analysis (wpdec and wpcoef), Neural Network Toolbox for BP neural network implementation (feedforwardnet and train), Optimization Toolbox for solving the linear programming problem in EMD computation (linprog), and Statistics and Machine Learning Toolbox for KNN classification (fitcknn and predict). The EMD was implemented by solving the transportation problem using linear programming. All experiments were condu....
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The experimental environment and platform are shown in Figure 2. From left to right, the platform consists of a fan-bearing assembly, an induction motor, and a drive unit. The central portion connects these components to a torque transducer/encoder via a coupling, and the rightmost section serves as the dynamometer. The control electronics are not depicted. EDM technology was used to simulate pitting faults on bearings, ranging from weak to severe conditions. Vibration data were collected us.......
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The present study proposes a KNN-based fault diagnosis method for rolling bearings that integrates distribution differences through EMD and feature importance through MIV. Experimental results on a rolling bearing dataset containing four health states (normal, inner race fault, rolling element fault, and outer race fault) demonstrate the effectiveness of the proposed approach. The proposed KNN–MIV–EMD method achieves the highest classification accuracy of 99.43% at K = 3, outperforming traditional KN.......
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The authors declare no conflicts of interest.
This work was financially supported by the Key Scientific Research Projects of Colleges and Universities in Henan Province (25A580011) and the Scientific and Technological Research Project in Henan Province (262102210057).
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| Name | Company | Catalog Number | Comments |
|---|---|---|---|
| Acquisition System | |||
| Data Recorder (16-channel) | Anti-aliasing filter, 24-bit ADC; dynamic range >90 dB; Case Western Reserve University, Cleveland, OH, USA Fault Type and Size (inch): All fault types Load (HP): All Sampling Frequency: 12 kHz or 48 kHz Purpose in Study: High-quality data acquisition File Naming Convention: N/A | ||
| Data Subset | |||
| Data Selection for This Study | Drive-end data, 12 kHz sampling, 4 load conditions; CWRU Bearing Data Center (https://engineering.case.edu/bearingdatacenter/download-data-file) Fault Type and Size (inch): 7 conditions × 4 loads = 28 subsets Load (HP): All Sampling Frequency: 12 kHz Purpose in Study: Model training and testing File Naming Convention: Custom selection | ||
| Label Information | |||
| Fault Class Labels | One-hot encoding format Fault Type and Size (inch): [1,0,0,0,0,0,0] for Normal … Load (HP): All Sampling Frequency: N/A Purpose in Study: Supervised learning labels File Naming Convention: Label_vector.mat | ||
| Sensor | |||
| Accelerometer (Drive End) | ICP accelerometer; position: 12 o’clock; sensitivity ~500 mV/g; Drive end bearing housing Fault Type and Size (inch): All fault types Load (HP): All Sampling Frequency: 12 kHz or 48 kHz Purpose in Study: Primary vibration signal acquisition File Naming Convention: DE_time_series | ||
| Accelerometer (Fan End) | ICP accelerometer; sensitivity ~500 mV/g; Fan end bearing housing Fault Type and Size (inch): All fault types Load (HP): All Sampling Frequency: 12 kHz or 48 kHz Purpose in Study: Auxiliary/comparison signal File Naming Convention: FE_time_series | ||
| Test Bearing | |||
| Ball Bearing (Healthy) | Deep groove ball bearing (6205 type); SKF (commonly used in CWRU setup) Fault Type and Size (inch): Normal Load (HP): 0, 1, 2, 3 Sampling Frequency: 12 kHz or 48 kHz Purpose in Study: Baseline condition File Naming Convention: Normal_0.mat | ||
| Ball Bearing (Inner Race Fault) | Single-point fault via EDM Fault Type and Size (inch): Inner Race (IR) @ 0.007", 0.014", 0.021", 0.028" Load (HP): 0, 1, 2, 3 Sampling Frequency: 12 kHz or 48 kHz Purpose in Study: Inner race fault validation File Naming Convention: IR007_1.mat | ||
| Ball Bearing (Outer Race Fault) | Single-point fault via EDM (6 o’clock position) Fault Type and Size (inch): Outer Race (OR) @ 0.007", 0.014", 0.021", 0.028" Load (HP): 0, 1, 2, 3 Sampling Frequency: 12 kHz or 48 kHz Purpose in Study: Outer race fault validation File Naming Convention: OR021_2.mat | ||
| Ball Bearing (Ball Fault) | Single-point fault via EDM Fault Type and Size (inch): Ball (B) @ 0.007", 0.014", 0.021", 0.028" Load (HP): 0, 1, 2, 3 Sampling Frequency: 12 kHz or 48 kHz Purpose in Study: Ball element fault validation File Naming Convention: B014_3.mat | ||
| Test Rig | |||
| Machinery Fault Simulator | Motor-driven system with adjustable load; accelerometer mounted on bearing housing; Case Western Reserve University, Cleveland, OH, USA Fault Type and Size (inch): N/A Load (HP): 0, 1, 2, 3 Sampling Frequency: 12 kHz or 48 kHz Purpose in Study: Source of fault dataset File Naming Convention: N/A |