Abstract Digital twin (DT) is a virtual mirror (representation) of a physical world or a system along its lifecycle. As for a complex discrete manufacturing system (DMS), it is a digital model for emulating or reproducing the functions or actions of a real manufacturing system by giving the system simulation information or directly driven by a real system with proper connections between the DT model and the real-world system. It is a key building block for smart factory and manufacturing under the Industry 4.0 paradigm. The key research question is how to effectively create a DT model during the design stage of a complex manufacturing system and to make it usable throughout the system’s lifecycle such as the production stage. Given that there are some existing discussions on DT framework development, this paper focuses on the modeling methods for rapidly creating a virtual model and the connection implementation mechanism between a physical world production system at a workshop level and its mirrored virtual model. To reach above goals, in this paper, the discrete event system (DES) modeling theory is applied to the three-dimension DT model. First, for formally representing a manufacturing system and creating its virtual model, seven basic elements: controller, executor, processor, buffer, flowing entity, virtual service node and logistics path of a DMS have been identified and the concept of the logistics path network and the service cell is introduced to uniformly describe a manufacturing system. Second, for implementing interconnection and interaction, a new interconnection and data interaction mechanism between the physical system and its virtual model for through-life applications has been designed. With them, each service cell consists of seven elements and encapsulates input/output information and control logic. All the discrete cells are constructed and mapped onto different production-process-oriented digital manufacturing modules by integrating logical, geometric and data models. As a result, the virtual-physical connection is realized to form a DT model. The proposed virtual modeling method and the associated connection mechanism have been applied to a real-world workshop DT to demonstrate its practicality and usefulness.

中文翻译：

---

如何为数字孪生应用建模和实现物理模型和虚拟模型之间的连接

摘要 数字孪生（DT）是物理世界或系统在其生命周期中的虚拟镜像（表示）。对于复杂的离散制造系统（DMS），它是一种数字模型，用于通过提供系统仿真信息来模拟或再现真实制造系统的功能或动作，或由真实系统直接驱动，并在 DT 模型和现实世界的系统。它是工业 4.0 范式下智能工厂和制造的关键构建块。关键研究问题是如何在复杂制造系统的设计阶段有效地创建 DT 模型，并使其在整个系统生命周期（例如生产阶段）中可用。鉴于已有一些关于 DT 框架开发的讨论，本文重点介绍了快速创建虚拟模型的建模方法以及车间级物理世界生产系统与其镜像虚拟模型之间的连接实现机制。为达到上述目标，本文将离散事件系统（DES）建模理论应用于三维DT模型。首先，为了正式表示制造系统并创建其虚拟模型，确定了 DMS 的控制器、执行器、处理器、缓冲区、流动实体、虚拟服务节点和物流路径七个基本要素，并确定了物流路径网络的概念和引入服务单元来统一描述一个制造系统。二、为实现互联互通，设计了一种新的物理系统与其虚拟模型之间的互连和数据交互机制，用于终身应用。有了它们，每个服务单元由七个元素组成，并封装了输入/输出信息和控制逻辑。通过集成逻辑、几何和数据模型，所有离散单元被构建并映射到不同的面向生产过程的数字制造模块。从而实现虚拟物理连接，形成DT模型。所提出的虚拟建模方法和相关的连接机制已应用于现实世界的车间 DT，以证明其实用性和实用性。每个服务单元由七个元素组成，封装输入/输出信息和控制逻辑。通过集成逻辑、几何和数据模型，所有离散单元被构建并映射到不同的面向生产过程的数字制造模块。从而实现虚拟物理连接，形成DT模型。所提出的虚拟建模方法和相关的连接机制已应用于现实世界的车间 DT，以证明其实用性和实用性。每个服务单元由七个元素组成，封装输入/输出信息和控制逻辑。通过集成逻辑、几何和数据模型，所有离散单元被构建并映射到不同的面向生产过程的数字制造模块。从而实现虚拟物理连接，形成DT模型。所提出的虚拟建模方法和相关的连接机制已应用于现实世界的车间 DT，以证明其实用性和实用性。