Anomaly detection of tripod shafts using modified Mahalanobis distance

Abstract

The tripod shafts used in high-speed trains transmit the power of a motor to axle reduction units. A tripod shaft is designed as a shaft with a protective fuse because the load applied to the reduction units is very large during operation. Fuse failure can lead to accidents and economic loss, such as train service interruption and repair problems at the accident site. Therefore, detecting the faults of fuses used in tripod shafts by using sensors is necessary. In this study, torsion fatigue tests for the failure modes were conducted, and strain data were collected by strain sensors from around the fuse of the shaft. The modified Mahalanobis distance was employed as the health indicator, and the fuse thresholds for the anomaly detection (AD) were defined using the three-sigma method. The AD performance of the tripod shafts was evaluated by comparing the results with real crack detection times.