Zhen Jia 1, Zhenbao Liu 1, Chin-Man Vong 2, and Michael Pecht 3
1 Northwestern Polytechnical University, Xi’an 710072, China
2 Department of Computer and Information Science, University of Macau, Macau 999078, China
3 CALCE, Center for Advanced Life Cycle Engineering, Department of Mechanical Engineering, University of Maryland, College Park, Maryland 20740, USA
Rotating machinery plays a vital role in industrial systems, in which unexpected mechanical faults during operation can lead to severe consequences. For fault prevention, many fault diagnostic methods based on vibration signals are available in the literature. However, vibration signals are obtained by using different types of sensors, which can cause sensor installation issues and damage the rotating machinery. In addition, this kind of data acquisition via vibration signal induces a large amount of signal noise during machine operation, which will challenge the later fault diagnosis. A recent fault detection method based on infrared thermography (IRT) for rotating machinery avoids these issues. However, the corresponding literature is limited by the fact that the characteristics of the manual design cannot fully characterize the fault, so that the diagnostic accuracy cannot exceed the diagnostic method based on the vibration signals. This paper introduces a popular image feature extraction method into the fault diagnosis of rotating machinery based on IRT for the first time. Capturing the IRT images of the rotating machinery in different states firstly, and then two popular feature extraction methods for IRT images, bag-of-visual-word (BoVW), and convolutional neural network (CNN), are tested in turn. Finally, the extracted features are classified to implement automatic fault diagnosis. The developed method is applied to analyze the experimental IRT images collected from bearings, and the results demonstrate that the developed method is more effective than the traditional methods based on vibration signals.