Human Digital Twins: Enhancing Interactions with Digital Ecosystems. Extended discussion of challenges and comparison on how they are addressed by the proposed architecture and other proposals

The emergence of Digital Twins (DTs) has transformed domains like Industry 4.0 or automotive, enabling advanced insights and predictive maintenance, driving efficiency and innovation. With the evolution towards human-centric domains, such as Industry 5.0 or intelligent vehicles, the need for Human Digital Twins (HDTs), human digital representations with the aim to align human interactions with the system's design and its performance, arises. HDTs, linked to human interactions in various contexts, seek to improve well-being, safety, and productivity by integrating human factors into digital systems. However, they face unique considerations and challenges compared to traditional DTs. We provide an overview of distributed multi-context HDTs, highlighting their utility in various domains. We propose an architecture designed to address key challenges in their development and deployment, including data management, privacy, and interoperability.  In this document we provide an extended discussion of challenges and comparison on how they are addressed by the proposed architecture and other proposals