Monitoring a machine and the insight it provides for appropriate maintenance is of prime importance for the modern industry. While this is fully supported in Industry 4.0, many manufacturing units today are unable to use its technologies. One of the major reasons behind that is the lack of onboard sensors to capture and communicate appropriate data from a legacy machine. Retrofitting is considered an efficient solution to include legacy machines in an industry 4.0 ecosystem by adding external sensing and connectivity. As a proof of concept, in this paper we consider an induction motor for retrofitting, a major component of any manufacturing unit. We further show how retrofitting can help in making legacy machines compliant to the new technologies from Industry 4.0. Finally, visualization of the collected data is performed over a web based Augmented Reality application. The choice for a web-based Augmented Reality application was made to enable monitoring of the sensor data over a multitude of devices.
Condition-based maintenance (CBM) is becoming a necessity in modern manufacturing units. Particular focus is given to predicting bearing conditions as they are known to be the major reason for machine down time. With the open-source availability of different datasets from various sources and certain data-driven models, the research community has achieved good results for diagnosing faults in bearing fault datasets. However, existing data-driven fault diagnosis methods do not focus on the changing conditions of a machine or assume all conditional data are available all the time. In reality, conditions vary over time. This variability can be based on the measurement noise and operating conditions of the monitored machines such as radial load, axial load, rotation speed, etc. Moreover, the availability of the data measured in varying operating conditions is scarce, as it is not always feasible to collect in-process data in every possible condition or setting. Considering such a scenario, it is necessary to develop methodologies that are robust to conditional variability, i.e., methodologies to transfer the learning from one condition to another without prior knowledge of the variability. This paper proposes the usage of latent values of an auto-encoder as robust features for inter-conditional fault classification. The proposed robust classification method MLCAE-KNN is implemented in three steps. First, the time series data are transformed using Fast Fourier Transform. Using the transformed data of any one condition, a Multi-Layer Convolutional Auto-Encoder (MLCAE) is trained. Next, a K-Nearest Neighbors (KNN) classifier is trained based on the latent features of MLCAE. The so-trained MLCAE-KNN is then used to predict the fault class of any new observation from a new condition. The results of using the latent features of the Auto-Encoder show superior inter-conditional classification robustness and superior accuracies compared to the state-of-the-art.
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