Manufacturing enterprises are facing the need to align themselves to the new information technologies (IT) and respond to the new challenges of variable market demand. One of the key enablers of this IT revolution toward Smart Manufacturing is the digital twin (DT). It embeds a “virtual” image of the reality constantly synchronized with the real operating scenario to provide sound information (knowledge model) to reality interpretation model to draw sound decisions. The paper aims at providing an up-to date picture of the main DT components, their features and interaction problems. The paper aims at clearly tracing the ongoing research and technical challenges in conceiving and building DTs as well, according to different application domains and related technologies. To this purpose, the main questions answered here are: ‘What is a Digital Twin?’; ‘Where is appropriate to use a Digital Twin?’; ‘When has a Digital Twin to be developed?’; ‘Why should a Digital Twin be used?’; ‘How to design and implement a Digital Twin?’; ‘What are the main challenges of implementing a Digital Twin?’. This study tries to answer to the previous questions funding on a wide systematic literature review of scientific research, tools, and technicalities in different application domains.

制造企业面临着使自己适应新信息技术（IT）并应对变化的市场需求的新挑战的需求。数字孪生（DT）是这场IT向智能制造革命的关键推动力之一。它嵌入不断与真实操作场景同步的真实“虚拟”图像，以向真实解释模型提供声音信息（知识模型）以做出合理的决策。本文旨在提供最新的主要DT组件，它们的功能和交互问题的图片。本文旨在根据不同的应用领域和相关技术，明确追踪在构思和构建DT方面正在进行的研究和技术挑战。为此，这里要回答的主要问题是：“什么是数字孪生兄弟？”；“哪里适合使用Digital Twin？”；“何时会开发出Digital Twin？”；“为什么要使用Digital Twin？”；“如何设计和实现数字双胞胎？”；“实施数字双胞胎的主要挑战是什么？”。本研究试图回答以前的问题，这些问题来自对不同应用领域的科学研究，工具和技术进行广泛的系统文献综述。