# Research on a Real-Time Control System for Discrete Factories Based on Digital Twin Technology
## 5 Conclusions  
In this article, the relationship between the gear factory and the discrete factory is clarified. The relevant research results and the current application status of digital twin technology are analyzed. The real-time control system of a gear factory and the composition of a digital twin gear factory are compared. The software architecture of a real-time control system system is researched. A digital twin gear factory is established, and a prototype software of the real-time control system is obtained. The final conclusions are as follows:  
1. A gear factory is a typical discrete manufacturing factory, and the research methods and achievements of a real-time control system for the dual gear factory based on digital twin technology are also suitable for other discrete factories.
2. The digital factory is just the software of the real-time control system of the digital twin factory. The research on a real-time control system mainly focuses on the software of a real-time control system or focuses on the digital factory.
3. A model for the digital twin gear factory is put forward based on the characteristics of gear factories. This model can transform the software development of a real-time control system into the development of a digital factory, laying an important technical path for researchers studying real-time control systems.
4. A human-computer interaction architecture for the real-time control system is put forward. It consists of three parts as follows: a monitoring module, a virtualizing module, and a controlling module. At work, it appears as three interactive interfaces as follows: a monitoring window, a virtualizing window, and a controlling window. A template for the software development of a real-time control system is proposed.
5. The virtual factory and some visualizing processes are created using 3D MAX and WebGL technology, and the device communication and interface management are implemented with OPC UA and REST standards. These technologies and standards can improve the software development efficiency of a real-time control system, thereby accelerating the development of virtual technology.
6. A prototype software of the real-time control system for the factory, which is specialized in manufacturing the intermediate shaft dual gear of a new energy vehicle gearbox, is developed. But only a small number of functions for monitoring, virtualizing, and controlling can be achieved and need to be further improved. The failure to make the software of the real-time control system more powerful and mature is not due to technical reasons, but rather the authors' insufficient understanding of the prototype factory and excessive software development workload.  
Conceptualization; Methodology and project administration, S.J.; Writing original draft and developing software, F.Y., B.W. and M.Z.; Supervision and data curation, Y.W. All authors have read and agreed to the published version of the manuscript.  
This research was partially funded by the National High-tech R&D Program of China (Grant No. 2019 AA043002), and the National Natural Science Foundation of China (Grant No. 51605442).  
Not applicable.  
The data presented in this study are available on request from the corresponding authors. The data are not publicly available due to corporate data privacy.  
The authors thank the Zhejiang Shuang Huan Transmission Machinery Co., Ltd. for providing a research site for dual gear production.  
The authors declared no potential conflict of interest with respect to the research, authorship, and/or publication of this article.