I. Introduction
Cyber–physical system can connect the cyber world with the physical production process and manual operations, which is recognized as a promising accelerator for understanding the production process, improving product quality, enhancing industrial security, realizing sustainably production, and saving labor costs [1], [2]. As a vitally important part of fabrication, the process industry is facing reformulation with the emerging of cyber–physical systems [3]. Process monitoring systems together with data-driven techniques, especially machine learning, are being actively developed for implementations in modern smart factories to improve operation efficiency [4].