自工業4.0 的概念被提出，為了提升製造效率與產品良率，同時降低人力成本與機台無預警停機所造成的虧損，建立實用的狀態診斷系統已然成為各界努力的目標，同時隨著電腦運算能力的提升，人工智慧模型的概念將大幅增加實現此目標的可能性，但現今之研究已漸漸產生過度依賴人工智慧的狀況，可能因過度聚焦於模型參數的調整而使模型變得過於複雜，此外在模型方面係以使用彈性較高的非監督式機器學習模型為本研究所用，此方法因缺乏客觀的量化方式作為訓練效果的評估依據而較少學者直接用以作為診斷模型，適當的量化方法將有助於純非監督式模型的建立並探討最佳模型參數，故本研究將探討領域知識對於模型訓練的助益並建立量化指標作為模型選用依據，最後以應用範圍廣泛之滾珠軸承作為應用對象進行概念的驗證。本研究透過執行轉子不平衡、軸承潤滑流失與軸承潤滑汙染三種失效模擬，並藉由多種感測器蒐集完整且全面的物理訊號，接著使用時域與頻域指標進行特徵萃取，隨後有系統地探討特徵指標與失效狀態間的關係，篩選出靈敏指標建立狀態診斷流程並作為非監督式狀態診斷模型的發展基礎，最後吾人使用自編碼器配合分群演算法建立狀態診斷模型，並根據訓練結果建立一個量化方法以量化自編碼器之訓練效果。根據實驗成果，本研究提出之診斷模型能夠有效分辨軸承之失效種類與程度，且在複合失效中仍然適用，而指標篩選對於訓練效果的提升能在可視化圖形中觀察得知並應用本研究之量化指標獲得驗證。綜合探討結果，本研究成功以領域知識協助建立非監督式診斷模型且首次結合客觀的量化方式評估自編碼器訓練結果，此研究流程可被拓展至其他機具次系統，增進智慧工廠中應用的實務價值。

The qualities of machined products are largely depended on the status of machines in various aspects. As a result, appropriate condition monitoring would be essential for both quality control and longevity assessment. Ball bearings are widely used in rotating components and definitely influence the operation quality of machines. Their faults are one of the main reasons that make machines break down and this problem should be investigated. Recently, with the advance in information technology, pure data driven approaches such as machine learnings have been widely applied in status diagnosis. However, the accuracy of those predictions strongly relys on the original data, which largely depends on the selected sensors and signal features. Furthermore, for unsupervised machine learning schemes, although they could avoid the concern of labelling in training, they lack a quantified evaluation of the training results. How to address these concerns is thus not a trivial issue. In this work, by utilizing ball bearing status diagnosis as the addressed problem, a diagnosis flow is developed to accessing the status of bearings in their imbalance, lubrication, and grease contamination levels based on unsupervised machine learning. Multiple sensors are hired to collect data and various statistical methods are used for data reduction and feature extraction. Through systematic analysis, it is possible to find the most sensitive features. Those indexes are then fed into autoencorder for training the collected data to recognize the possible bearing failure type and status. Then, classification models are used to obtain status labels. Furthermore, the effect of sensor index selection on the clustering efficiency are then also examined. The investigation results show that the hired machine learning method performs well with appropriate feature indexes. Not only the severe levels in the same category, but also between different types of failure can be distinguished. On the other hand, improper feature used would lead to poor and even indistinguishable clustering. Furthermore, a whole diagnosis process flow is proposed for counting possible multiple causes of failures. Finally, a model based on the second norm to quantify the separation level of each cluster is proposed as the measure for training results of autoencoder models. The proposed diagnosis flow should be useful for improving the prediction accuracy on reliability assessment in bearing and rotating machinery related applications.

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