A digital twin (DT) is classically defined as the virtual replica of a real-world product, system, being, communities, even cities that are continuously updated with data from its physical counterpart, as well as its environment. It bridges the virtual cyberspace with the physical entities and, as such, is considered to be the pillar of Industry 4.0 and the innovation backbone of the future. A DT is created and used throughout the whole life cycle of the entity it replicates, from cradle to grave, so to speak. This article focuses on the present state of the art of DTs, concentrating on the use of DTs in industry in the context of smart manufacturing, especially from the point of view of plantwide optimization. The main capabilities of DTs (mirroring, shadowing and threading) are discussed in this context. The article concludes with a perspective on the future.

This article is part of the theme issue ‘Towards symbiotic autonomous systems’.

数字孪生 (DT) 经典定义为现实世界产品、系统、存在、社区甚至城市的虚拟复制品，这些产品、系统、社区甚至城市都不断更新来自其物理对应物及其环境的数据。它将虚拟网络空间与物理实体连接起来，因此被认为是工业 4.0 的支柱和未来的创新支柱。可以说，DT 在它复制的实体的整个生命周期中创建和使用，从摇篮到坟墓。本文重点介绍 DT 技术的现状，重点关注智能制造背景下工业中 DT 的使用，尤其是从全厂优化的角度来看。在此上下文中讨论了 DT 的主要功能（镜像、阴影和线程）。

这篇文章是主题问题“走向共生自治系统”的一部分。