Requirements Engineering for Digital Twins: a Cross-Domain Systematic Literature Review

Digital Twins (DTs) are attracting growing interest for their potential to enhance the design and operation of complex systems such as Cyber-Physical Systems. A DT is an up-to-date virtual representation of real-world entities and processes, capable of reflecting current and past states and simulating future scenarios using Artificial Intelligence-related technologies. DTs are applied across domains like smart manufacturing and healthcare. Despite recent efforts to propose holistic approaches to DT design and development, a critical gap remains: the integration of Requirements Engineering (RE) practices into the DT development lifecycle is often overlooked or insufficiently addressed. This shortage can lead to DT architectures that fail to fully meet system or stakeholder goals. This paper conducts a Systematic Literature Review to assess the extent to which RE processes have been incorporated into DT development. From an initial set of 1230 publications, 20 were selected for detailed analysis. The study examines RE methods and techniques across different phases and evaluates their maturity. Findings show that few works explicitly address RE in DT development, with most contributions focusing on early RE stages and often overlooking essential DT system properties. It concludes that there is a significant lack of structured RE processes, methods, and tools tailored for DT engineering.