Abstract

Due to the recent rapid growth of advanced sensing and production technologies, the monitoring and diagnosis of multivariate process operating performance have drawn increasing interest in process industries. The multivariate statistical process control (MSPC) chart is one of the most commonly used tools for detecting process faults. However, an out-of-control MSPC signal only indicates that process faults have intruded the underlying process. Identifying which of the monitored quality variables is responsible for the MSPC signal is fairly difficult. Pinpointing the responsible variable is vital for process improvement because it effectively determines the root causes of the process faults. Accordingly, this identification has become an important research issue concerning recent multivariate process applications. In contrast with the traditional single classifier approach, the present study proposes hybrid modeling schemes to address problems that involve a large number of quality variables in a multivariate normal process. The proposed scheme includes multivariate adaptive regression splines (MARS), logistic regression (LR), and artificial neural network (ANN). By applying MARS and LR techniques, we may obtain fewer but more significant quality variables, which can serve as inputs to the ANN classifier. The performance of our proposed approaches was evaluated by conducting a series of experiments.

Highlights

  • A multivariate process monitors two or more quality variables

  • The significant variables selected in this stage served as the input variables of the artificial neural networks (ANN)

  • The ANN has been criticized for its long training process; the combination of logistic regression (LR)/multivariate adaptive regression splines (MARS) and ANN is a good alternative for performing classification tasks

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Summary

Introduction

A multivariate process monitors two or more quality variables. When a signal is triggered by the multivariate statistical process control (MSPC) chart, process personnel are typically only aware that the underlying process is in an unstable state. Identifying which of the monitored quality characteristics (or variables) is responsible for this MSPC signal is challenging. A literature review has shown that there are different kinds of approaches to investigate on source identification of faults in a multivariate process. The first type of approach uses various graphical techniques, such as polygonal charts [1], line charts [2], multivariate profile charts [3], and boxplot charts [4] to assist in determining the quality variables at fault in a process. The operations of these graphical approaches are tedious and subjective

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