## 4 Results
### Data Analysis for Edge Processing Content Determination  
From the cycle waveform obtained by the cycle waveform cutting algorithm, features effective for detecting bolt loosening on the ball screw support side support are extracted, and the edge processing content of the sensor device is determined. In this evaluation experiment, the stage moves in two parts during one cycle of the ball screw of the testbed: uniform motion from the left end to the right end and uniform motion from the right end to the left end. Therefore, in order to focus on the vibration during the stage movement, the data for the relevant part are extracted from the respective cycle waveforms. Figure 18 shows the parts to be extracted as the parts of uniform motion from the left end to the right end and from the right end to the left end. Here, in extracting the data, the 700 th sample from the beginning of the cycle waveform is considered as the constant velocity motion from the left end to the right end, and the 1300 th sample to the 2000 th sample as the constant velocity motion from the right end to the left end, because each cycle waveform is cut out with a similar length. Figure 16: Cycle waveform at 11 N of torque. Figure 17: Cycle waveform at 1 N of torque. The evolution of the variance values for the uniform motion part of the extracted cycles was then plotted on a graph. The evolution of the dispersion values for the uniform motion from the leftmost to the rightmost is shown in Figure 19 and that for the uniform motion from the rightmost to the leftmost is shown in Figure 20. In each graph, a moving average of 50 points is applied to reduce the influence of cycle-to-cycle variation. In the case of uniform motion from the left end to the right end, the dispersion value tends to be higher for a tightening torque of 1 N up to around 300 cycles. However, after 300 cycles, the dispersion value for a tightening torque of 11 N repeatedly increased and decreased, and the dispersion value for a particularly large portion was similar to that for a tightening torque of 1 N. It was confirmed that the threshold value could not be used to determine the dispersion value. In contrast, in the case of uniform motion from the right end to the left end, it was confirmed that the dispersion values for a tightening torque of 11 N tended to be larger than those for a tightening torque of 1 N overall. However, in the vicinity of 200, 480 and 600 cycles, where the dispersion value for a tightening torque of 1 N is larger, the dispersion value for a tightening torque of 11 N is larger than that for a smaller torque, leading to misjudgment by the threshold value in these areas. Based on the above results, attention was paid to the dispersion during uniform motion from the right end to the left end, where the greatest difference was observed between a tightening torque of 11 N and a tightening torque of 1 N.  
Figure 19: Dispersion values in uniform motion from the left end to the right end. Figure 18: Operating point of the cycle waveform at 11 N of torque. Here, a difference in the variance of the waveform immediately after the start of uniform motion from the right end to the left end was observed in the cycle waveform of Figure 16, which is a cycle waveform with a tightening torque of 11 N, and in the cycle waveform of Figure 17, which is a cycle waveform with a tightening torque of 1 N. Therefore, 100 samples from the 1300 th sample to the 1400 th sample in each cycle waveform were extracted as the data immediately after the start of uniform motion from the right end to the left end, and the variance was determined. However, a moving average of 50 points is applied to reduce the effect of cycle-to-cycle variations. In the dispersion value focused immediately after the start of uniform motion from the right end to the left end, it was confirmed that the dispersion value for a tightening torque of 11 N was greater than that for a tightening torque of 1 N in all cycles.