Editorial: Human digital twins for medical and product engineering

The current trend towards digitalization of human-centred engineering processes in conjunction with advances in (bio-)mechanistic modelling, high-performance computing, artificial intelligence (AI) and sensor technology leads to unprecedented transformation potentials in medical, product and human factors engineering. These advancements are significantly enhancing human-technology interaction and improving medical treatment outcomes. Biomechanical simulations hold high potential by revealing the processes and inner strain conditions of the human body. For reliable simulation results, a suitable model is required, as well as a measurement, estimation, or prediction approach to analyse human motion behaviour, its interaction with the environment and, if present, its interaction with technology. In this context, we refer to a human digital twin as a virtual representation or digital replica of an individual, created using data from various sources, including sensors, medical records, and other digital inputs. This digital twin mirrors certain physical and behavioural characteristics of the person, enabling simulations, predictions, and analyses. If interactions between humans and technology are considered, the concept of digital twin couples is applicable. This concept facilitates the use of human digital twins and digital product twins (within its environment) in conjunction with different data streams, which can be measured on the human, on the product, or at their interface. The combined use of different data streams may enable a more accurate estimation of the states within the overall human-technology system in terms of a modelbased systems engineering approach. This subsequently allows to optimize physical humantechnology interactions based on simulations, estimations, or predictions with the digital twin couples as well as data transfer between virtual and physical instances of human and technology.The goal of this Research Topic was to explore human digital twins as personalized biomechanical models for person-specific simulations and their application in human-centred engineering. Such simulations allow for computing biomechanical variables from wearable or unobtrusive sensors instead of requiring expensive gold standard lab-based equipment.