Cost sensitive active learning using bidirectional gated recurrent neural networks for imbalanced fault diagnosis.

• A framework based on Bidirectional Gated Neural Networks is proposed for fault diagnosis with uncertainty in dynamic environments. • A Sample Sensitive Bidirectional Gated Neural Networks model is developed to tackle imbalanced fault diagnosis challenges. • Cost sensitive active learning is used to explore unlabeled data. • Effective methods are developed to address both binary Fault Diagnosis and multi-class Fault Diagnosis. Most existing fault diagnosis methods may fail in the following three scenarios: (1) serial correlations exist in the process data; (2) fault data are much less than normal data; and (3) it is impractical to obtain enough labeled data. In this paper, a novel form of the bidirectional gated recurrent unit (BGRU) is developed to underpin effective and efficient fault diagnosis using cost sensitive active learning. Specifically, BGRU is devised to consider the dynamic behavior of a complex process. In the training phase of BGRU, the idea of weighting each training example is proposed to reduce the effect of class imbalance. Besides, in order to explore the unlabeled data, cost sensitive active learning is utilized to select the candidate instances. The effectiveness of the proposed method is evaluated on the Tennessee Eastman (TE) dataset and a real plasma etching process dataset. The experiment results show that the proposed cost senstive active learning bidirectional gated recurrent unit (CSALBGRU) method achieves better performance in both binary fault diagnosis and multi-class fault diagnosis. [ABSTRACT FROM AUTHOR]