## 1 Introduction  
Conceptualization, design, fabrication, implementation, and post-launch evaluation are integral components of the product development process [1]. The effectiveness and efficiency of newly introduced products are directly influenced by the management of the development process, which necessitates the establishment of product and process design standards, among other factors, to ensure manufacturability with minimal environmental impact. Detecting issues early in the product development stage (simulation) is important [2]. When problems are identified around or after the product launch, the cost of rectification escalates dramatically. This can be attributed to the fact that, at this stage of development, production resources are nearly exhausted, and modifications become increasingly complex and costly. In contrast, all prior phases, from definition to optimization, are conducted within a virtual environment that is simple, efficient, and inexpensive to modify [2]. From an ergonomic standpoint, the early identification of issues during virtual manufacturing not only saves time and resources but also minimizes workers' exposure to unnecessary injury risks, thereby enhancing workplace well-being [3]. In the context of Industry 4.0, advancements in technology and the automation of production processes have created a conducive environment for the implementation of various technologies that support multiple stages of this production process, ranging from activity monitoring to workplace enhancements [4]. Among these technologies are virtual simulations such as virtual reality (VR) and digital human modeling (DHM), both of which operate within a three-dimensional (3D) environment. Virtual reality is \"a computer-generated digital environment that can be experienced and interacted with as if it were real\" [5]. In contrast, DHM simulations are non-immersive, utilizing computer-generated mannequins to replicate human movements [6; 7]. Virtual simulation, in the context of VR and DHM technologies, employs computer modeling and simulation techniques that have been extensively utilized for over half a century across various sectors, including education, healthcare, entertainment, culture, sports, engineering, military forces, and more. However, these technologies have only recently emerged as valuable tools in the industrial sector [8]. Although scaling human models is one of the fundamental functions of digital human modeling (DHM), accurately representing the diversity of the human population remains challenging due to the significant variation in body sizes and shapes [9]. Despite their wide-ranging applications, these technologies have not yet been extensively explored by industries for physical ergonomics studies throughout the product development stages. Recent research highlights the growing interest in employing immersive technologies for ergonomics assessment in industrial settings. A systematic review, for example, mapped 250 patents and 18 scientific articles and revealed an exponential increase in innovations combining virtual reality and DHM for ergonomic applications in product development [10]. Their findings emphasize the strong potential of integrating the two technologies to detect ergonomic risks early in the design process, which could significantly reduce costs and enhance worker well-being. However, the authors note that despite broad consensus on these benefits, most existing studies and applications continue to address pre-designed manufacturing environments, where resources are already deployed, rather than focusing on proactive ergonomics during early development phases. Moreover, the integration of VR and DHM in a single analysis remains rare, suggesting a disconnect between academic advances and industrial adoption. This gap indicates the need for further applied research and experimental validation of integrated VR-DHM frameworks within the early stages of industrial product design.