## 3 Experiments and Analysis
### Experiment 2: The Laboratory Measurement Bearing Dataset  
#### 3.2.1 Experimental Data  
The rotor-bearing experimental system is mainly composed of speed regulating motor, gearbox, rotating shaft, turntable, and test bearing and corresponding test system. Its structure is shown in Figure 21. During the test, the motor drives the tested bearing to rotate through the gearbox, and the motor is controlled by the frequency converter to stabilize the speed of the tested bearing in a certain range. The accelerometer is a B&K4508 vibration sensor with sensitivity of 9.782 mV/g and frequency range of 0.1-8 kHz. The data acquisition card is NIUSB-9234 with four-channel C-series dynamic signal acquisition module with USB interface.  
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Methods** & **N** & **ORF** & **BF** & **IRF** & **Total** \\ \hline EEMD + MPE + SSDAE (proposed) & 100 & 99.33 & 99.33 & 100 & 99.60 \\ EEMD + MPE + Stacked AE & 98.00 & 98.67 & 98.00 & 96.67 & 97.80 \\ EEMD + MPE + SVM & 100 & 95.33 & 92.67 & 90.00 & 93.40 \\ EEMD + MPE + BPNN & 90.00 & 92.67 & 90.67 & 87.33 & 90.20 \\ \hline \hline \end{tabular}
\end{table}
Table 4: Classification accuracy (%) using different classification models.  
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Methods** & **N** & **ORF** & **BF** & **IRF** & **Total** \\ \hline EEMD-MPE (proposed) & 100 & 99.33 & 99.33 & 100 & 99.60 \\ VMD-PE & 100 & 100 & 99.33 & 98.67 & 99.20 \\ WP-EMD & 98.00 & 98.00 & 98.67 & 99.33 & 98.60 \\ EMDEE & 94.00 & 98.67 & 98.00 & 97.33 & 97.60 \\ \hline \hline \end{tabular}
\end{table}
Table 5: Classification accuracy (%) using different feature extraction methods.  
The bearing tested on the rotor-bearing test bench is HRB6304 rolling bearing, and its parameters are shown in Table 6. Vibration signals are collected by a vibration sensor installed in the vertical direction of the bearing seat. Speed control motor speed is 2000r/min, and the sampling frequency is set to 10 KHz. The experiment simulates six different fault types shown in Figure 22, including three single point faults and three compound faults. The single point faults are IRF, ORF and BF, and the compound faults are IRF + ORF, IRF + BF, ORF + BF. The fault diameter is 0.5334 mm and the fault depth is 2.1 mm. Through the test, 1050 samples of different bearing states are obtained, each sample length is 2048 points, and the specific conditions of the seven kinds of samples are shown in Table 7.  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Parameter** & **Inner Ring** & **Outer Ring** & **Pitch Diameter** & **Ball Diameter** & **Number of Balls** \\ \hline Value & 20 & 52 & 36 & 9.6 & 7 \\ \hline \hline \end{tabular}
\end{table}
Table 6: HRB6304 bearing parameters (mm).  
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**Fault Type** & **Training Samples** & **Test Samples** & **Sample Length** & **Sample Label** \\ \hline N & 300 & 150 & 1 \\ ORF & 300 & 150 & 2 \\ BF & 300 & 150 & 3 \\ IRF & 300 & 150 & 2048 & 4 \\ IRF+ORF & 300 & 150 & 5 \\ IRF+BF & 300 & 150 & 6 \\ ORF+BF & 300 & 150 & 7 \\ \hline \hline \end{tabular}
\end{table}
Table 7: Samples of the bearing in Experiment 2.  
Figure 21: Rotor-bearing experimental system.  
Figure 22: Bearing single point fault and compound fault.