ZfA special issue “Digital Human Modeling”—an opening message from the IEA Technical Committee Digital Human Modeling and Simulation

“Quo Vadis, Homo Sapiens Digitalis? The human in the digitized world of work” is the leading topic for this year’s autumn conference of the German Ergonomic Association. It is not the first time this question has evolved in the community of digital human modelers in Human Factors & Ergonomics—in fact it has been a guide for the Technical Committee (TC) Digital Human Modeling (DHM) and Simulation (TC DHMS) of the International Ergonomics Association (IEA) over the last 13 years. The TC DHMS was founded in 2009 by Thomas Alexander and Gunther Paul and is currently one of 25 TC of the IEA. The TC has a non-formal flexible membership structure; it is chaired by three academics and practitioners, Gunther Paul (Australia), Sofia Scataglini (Belgium) and Gregor Harih (Slovenia). Any delegates of national ergonomic societies contributing to the TC’s annual digital human modeling symposia may be considered members of the TC. In another perspective the TC counts all the registered and globally distributed 612 members of its managed and members only LinkedIn social network group (IEA TC Digital HumanModelling and Simulation, https://www.linkedin.com/groups/2401911/) which was founded in October 2009. The IEA presents the committee scope in a historic point of view (https://iea.cc/member/digital-human-modelingand-simulation/):

"Nowadays, digital modelling of physical humans and their behavior has in many ways and application areas matured from research into industrial application. Nevertheless, a large potential for further development remains. With regard to human simulation, digital human models (DHM) have become commonly used tools in virtual prototyping and human-centered product design. They support human-in-the-loop (HITL) ergonomic evaluation of new product designs during the early design stages of a product, by means of modeling anthropometry, posture, forces, motion, muscular effort or predicted discomfort. While DHM are currently still largely stand-alone applications, future DHM will be dominated by fully integrated CAE methods, realistic 3D design, and musculoskeletal and soft tissue modelling all the way down to the microscale molecular processes within single muscle fibers. Important aspects of current DHM research are functional analysis, model integration, and task simulation. Digital ('virtual'; 'analytic') humanoids provide streamlined and efficient support of product testing and verification, allowing for task-dependent performance and motion simulation. Beyond rigid body mechanics, soft tissue modeling will become a standard in future DHM. When addressing advanced issues beyond anthropometry and biomechanics in a holistic perspective, human mental modeling, behaviors, abilities, and skills must be considered in DHM. Recent projects have proposed a more comprehensive approach to human modelling by implementing perceptual, cognitive, and performance models, representing human behavior on a non-physiologic level. Through integration of algorithms from the artificial intelligence domain, the vision of a virtual human will become reality." The IEA TC DHMS aims to increase and foster the awareness of ergonomics in the development of DHM technology, identify and share research needs in the field of digital human modelling, share data, algorithms, tools, and methods in the digital human modelling community, inform ergonomists and the general public about DHM technologies, and promote the relevance of ergonomics to stakeholders in domains relevant to digital human modeling and simulation, such as product design, interaction design, human-machineinterface (HMI) engineering, marketing, and management. The TC organizes an annual DHM symposium as a marketplace for basic and applied DHM research and promotes commercial DHM solutions and related technologies. The TC supports the IEA Triennial Congress through delivery of a DHM thematic track of research presentations. The TC meets once a year, typically in connection with the DHM symposium.
For over 10 years and until 2009, DHM had been globally "owned" by automotive engineers and their ergonomists, and the Canadian SAFEWORK system, now fully integrated into Dassault's various digital engineering software suites, may be considered the first DHM platform aspiring to overcome this unhelpful limitation. In 2009 the International Society of Automotive Engineers (SAE) had called for their annual SAE 2009 "Digital Human Modeling for Design and Engineering" conference, with nominated areas of interest "biomechanics, cognition and perception, dynamics and impact, size and shape analysis, and applications"-then the grand financial crisis struck, and it should not happen. SAE decided to discontinue their investment into DHM and the IEA TC DHMS was born at the IEA triennial conference in Beijing.
"Quo Vadis, Homo Sapiens Digitalis?" was also the topic of my invited introductory lecture for my first professorial appointment at the University of South Australia in 2009. At the time I had just accepted a call from this young University in Adelaide, resigned from my position in manufacturing engineering at Mercedes Benz in Stuttgart and relocated to Australia. I titled my presentation "Towards realistic digital human models-where are we, and how far do we still have to go?". My lecture concluded with the following statement: "So the future in digital human modelling has already started. This future will be dominated by CAE methods, realistic 3D design, musculoskeletal and soft tissue modelling down to the micro-scale molecular activity within single muscle fibers, functional analysis, integration, simulation, digital/virtual/analytic prototypes (DMU), better support of testing and verification and the consideration of task dependent performance and motion. The future will also overcome the human-manikin and manikin-manikin variability in simulation results. Beyond rigid body mechanics, soft tissue modelling will become normal in DHM.
Fascinating examples for what can be achieved here may be found in the work of Prof. Karen Reynolds at Flinders University. As the past has shown, progress often requires Standardization. In DHM, a first step has been done with the provision of the standard EN ISO 15536-Ergonomics: Computer Manikins and Body Templates, Part 1: General Requirements. Through Standards Australia, ISO and the International Ergonomics Association technical committee on digital human modelling, Ergolab will continue to drive future standards in this domain. We have to and we will focus on a holistic approach to overcome system incompatibility, an example of this are the different file formats that are used; to provide common protocols, seamless integration with process management software systems, including product and process data. In manufacturing, such a solution needs to interface to assembly sequencing, product development, process & production planning, production performance analysis, workplace & workload analysis, and last but not least, incident and risk analysis. While in the past digital human models were dominated by Realism, a characteristic which expresses that the human model physically resembles a human but actually behaves non humanlike, at the Ergolab we believe that future DHM must embrace Likeness: this means that a potentially strange creature behaves like a human in motion, body language and expressions. Naturally, future models must strive for both, and Avatar has provided a fantastic vision of immersive technology to come." Much of this has been accomplished over the last 13 years in breathtaking developments.
In 2018 we felt the need to summarize the current stage of DHM science, technology and development with a focus on the body outer and posture analysis-some might already consider this to be the past of DHM in 2022! With the generous support from the TC and contributions from the larger DHM community, Sofia Scataglini and I eventually produced "DHM & Posturography" in 2019 (Scataglini and Paul 2019), a comprehensive 823-page compendium of DHM published by Elsevier Academic Press. The book provides an overview of the current stage of digital human models in the world, including developments in America, Asia, Australia and Europe, and across various disciplines such as the military, automotive, product design, and health sciences. It also discusses challenges in digital human modeling, including standardization and integration.
It only took three years and already developments in DHM have moved significantly beyond the content covered in this book. Strategic and significant funding from the European Union have accelerated the genesis of "insilico medicine" with stunning advances in DHM over the last ten years. The "Digital Twin", initially a NASA concept which found its way into the core philosophy of Industry 4.0 has immensely expanded the community of researchers and practitioners developing DHM technology.
To keep pace with these ever-accelerating advances in DHM, I joined forces with a biomedical specialist, Mohamed Doweidar in Spain and started a new project in 2020, a collection called "DHM & Medicine-The Digital Twin" (Paul and Doweidar 2022) to be published later this year-again by Elsevier Academic Press. The Digital Twin (DT) concept very much epitomizes our vision for the future of DHM well into the 2030s.
While previously a niche specialist discipline, with universities, start-ups and SME dominating the market offering, large industrial players have now entered the market of DHM, including Siemens, Dassault Systems and Philips.
Siemens Healthcare GmbH (2019) describe the value of a DT in a healthcare environment by saying that "A digital twin can help healthcare enterprises identify ways to enhance and streamline processes, improve patient experience, lower operating costs, and increase higher value of care. The digital twin creates models of physical spaces and processes. Then, cost and quality optimization parameters are examined and ultimately selected based on the insights gained from simulations leveraging the digital twin. Digital twin insights can be further enhanced with complimentary technologies like Real-Time Locating Systems (RTLS), which provides a robust data source and a means to test changes in layout, process, etc." Similarly, Philips have found interest in the DT because of the "importance of getting the whole picture", where "different data may point to different conclusions when viewed in isolation. Medical practitioners should ideally have an integrated understanding of a person's health", asking, "Could the 'digital patient'-a digital twin of the human body-be the means to this end?" and finding that "digital twins are proving to be a powerful paradigm for personalizing healthcare and making it more effective and efficient". They provide the examples of medical device testing and organ models that may support diagnosis and management. However, the digital patient concept goes beyond having "isolated models of different organs, a digital patient or 'health avatar' integrates every relevant piece of medical knowledge about you. A digital patient is a lifelong, integrated, personalized model of a patient that is updated with each measurement, scan or exam, and that includes behavioral and genetic data as well" (van Houten 2018).
The European EDITH project (https://www.edith-csa. eu/), which stands for 'Ecosystem for Digital Twins in Healthcare' is a strategic approach to develop a taxonomy of DT in healthcare and plan for their development and implementation in medical practice. EDITH mentions in silico medicine, health data and High-Performance Computing (HPC) as DT elements, however given its early days, does not yet provide the complete definition or visionary framework for the future of DHM. It aims to develop a roadmap and cloud-based repository of resources and best practice, controlled by a governance context of standards, regulations and meta-data. The project eventually includes an infrastructure component in the form of a simulation platform to "realize the vision of the integrated digital twin for personalized healthcare".
Digital Twin developments have obviously propelled digital human modeling into a next age, involving the next generation of scientists, bigger industry, higher politics, and a much broader cross-section of our societies.
The IEA TC DHMS thanks the German Ergonomic Society for making DHM their topic for this autumn conference and we thank ZfA for producing a worthy special issue-hopefully this effort will attract more young ergonomists to find interest in this exciting discipline.

Funding Open Access funding enabled and organized by CAUL and its Member Institutions
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