# Research on a Real-Time Control System for Discrete Factories Based on Digital Twin Technology
## 1 Introduction
described the information model of digital twins and introduced the advantages and potential of applying digital twin technology to part processing [5]. There are still many problems with flexibility, dynamics, complexity, data analysis, and other aspects in production management. There is a lack of real-time data perception and acquisition ability, no process-related database established, and no conditions for analyzing and making decisions for big data in order to control and optimize products in each stage. In 2011, Professor [PERSON] proposed the concept of the digital twin [6]. Digital twin technology is a simulation method, consisting of integrating multiple physical quantity, multiple scale, and multiple probability models, in which historical data and real-time updated data are used to depict and reflect the production process [7]. In 2016, [PERSON] et al. first applied the digital twin technology to the industrial area [8]. [PERSON] et al. applied the digital twin technology to the simulation of production design and processing for improving the management and control of products [9]. [PERSON] et al. proposed the concept of the digital factory and designed the five-dimensional model framework of the digital factory in order to study and analyze the main composition [10]. [PERSON] et al. applied the digital twin to research system modeling and process simulation with the aim of reducing the complexity of the simulation process [11; 12]. The five-dimensional model of the digital twin, as well as relevant application areas, were also proposed [13]. [PERSON] et al. designed and constructed instrument- and equipment-sharing laboratories using digital twin technology [14]. [PERSON] et al. proposed a three-dimensional detection algorithm based on digital twin technology, establishing the digital mapping between physical space and virtual space, thus solving the problem of pseudo correspondence in the traditional methods [15]. [PERSON] et al. designed a unified real-time ethernet communication structure based on ethernet standards, solving the real-time processing problem of workshop networks [16]. [PERSON] et al. deployed LTE (Long Term Evolution) networks in the workshop using 5 Gtechnology, achieving real-time production data [17]. [PERSON] et al. defined exchange data structures based on OPC UA (OLE (Object Linking and Embedding) for Process Control Unified Architecture) standards and used them for factory data exchanges [18]. [PERSON] et al. achieved cross network multi-database engine interconnection through two different OPC UA communication methods, effectively solving the problem of connecting different data and views [19]. [PERSON] et al. proposed a communication framework using an agent-based architecture for distributed manufacturing systems [20]. The authors of this article were committed to applying digital twin technology to quality management [21] and process control [22], as well as research concerning visualization software for digital twin gear factories [23]. This fully reflects that the research regarding a real-time control system for discrete factories based on digital twin technology has a solid foundation. This article aims to establish a real-time control system for the dual gear factory. The current application status of digital twin technology is investigated. A model for the digital twin gear factory is put forward based on the characteristics of gear factories, and the composition of a real-time control system for gear factories is clarified. Then, a human-computer interaction architecture for the real-time control system is proposed in order to establish the system software functional structure. Finally, the dual gear factory is applied to develop a set of software for the real-time control system.