1.2 Human‐Centered Disciplines
HF is a broad scientific and applied discipline. As a body of knowledge, HF is a collection of data and principles about human characteristics, capabilities, and limitations. This knowledge base is derived from empirical evidence from many fields and is used to help minimize the risk of systems by incorporating the diversity of human characteristics (England 2017). Ergonomics is the scientific discipline concerned with the understanding of interactions among humans and other elements of a system and the profession that applies theory, principles, data, and methods to design in order to optimize human well‐being and overall system performance (IEA 2018). The term “human factors” is generally considered synonymous with the term “ergonomics.” HF engineers or ergonomics practitioners apply the body of knowledge of HF to the design of systems to make them compatible with the abilities and limitations of the human user.
HF has always employed a systems approach; however, in large complex systems, it was recognized that the role of the human must be considered from multiple perspectives (Smillie 2019). HSI is the interdisciplinary technical process for integrating multiple human considerations into SE practice (DOA 2015). Seven HSI areas of concerns have been identified – manpower, personnel, training, HFE, health and safety, habitability, and survivability – all of which need to be addressed in an interconnected approach. The emphasis of the HSI effort is on the trade‐offs within and across these domains in order to evaluate all options in terms of overall system performance, risk, and personnel‐related ownership cost (SAE6906 2019). HSI provides a comprehensive snapshot of how human systems interaction has been addressed throughout the system development process by evaluating each of these domains as the system design progresses through different stages. It identifies what issues remain to be resolved, including their level of risk, and suggests potential mitigations.
Human factors integration (HFI) is a systematic process for identifying, tracking, and resolving human‐related issues ensuring a balanced development of both technological and human aspects of a system (Defence Standard 00‐251 2015). HFI is the term used in the United Kingdom equivalent to HSI. Similar to HSI, HFI draws on the breadth of the HF disciplines and emphasizes the need to facilitate HFI management activities of concern across seven similar domains: manpower, personnel, training, HFE, system safety, health hazard assessment, and social and organizational (England 2017). The methods and processes available for HFI can be broken down into both technical activities and management activities; HFI has a well‐defined process and can draw on many methods, tools, standards, and data in order to prevent operational and development risks (Bruseberg 2009).
1.3 Human Systems Engineering
The HSI discipline was established with the primary objective to enhance the success of the Department of Defense (DoD) systems by placing humans on more equal footing with design elements such as hardware and software (SAE6906 2019). SE is an interdisciplinary field of engineering and engineering management that focuses on how to design and manage complex systems over the system life cycle. While HSI is considered an enabler to SE practice, systems engineers need to be actively engaged to continuously consider the human as part of the total system throughout the design and development stages. HSE is the application of human principles, models, and techniques to system design with the goal of optimizing system performance by taking human capabilities and limitations into consideration (DOD 1988). HSE approaches the human system design from the perspective of the systems engineer and views the human component as a system resource. Human‐focused analyses that occur as part of the HSE evaluations determine the required interactions between users and technology and are essential to insure efficient processes and data exchange between the technology elements and the human users (Handley 2019a). In the United Kingdom, human‐centric systems engineering (HCSE) seeks better ways to address HF within mainstream SE while building on and optimizing the coherence of existing best practice. Similar to HSE, HCSE approaches HF from an SE viewpoint and aims to develop core SE practices that help engineering organizations adopt the best HF processes for their needs (England 2017).
HSE applies what is known about the human to the design of systems. It focuses on the tasks that need to be performed, the allocation of specific tasks to human roles, the interactions required among the human operators, and the constraints imposed by human capabilities and limitations. A key focus of HSE is on the determination of the human role strategy; this allocation determines the implications for manning, training, and ultimately cost (ONR 1998). The human elements of the system possess knowledge, skills, and abilities that must be accounted for in system design, along with their physical characteristics and constraints, similar to other technical elements of the system. The goal of HSE is to augment the system descriptions with human‐centered models and analysis; these purposeful models inform trade‐off analyses between system design, program costs, schedule, and overall performance (Handley 2019a). As part of the SE process, HSE incorporates the human‐related specifications into the system description to improve overall system performance through human performance analysis throughout the system design process.
1.4 Development of the HSE Framework
The HSE framework was developed for the SE community to provide a basis for categorizing and understanding applications of HSE for different types of sociotechnical systems. It was developed by cross‐referencing and aligning different aspects of domains, system types, and design stages with applicable HSE and HSI tools and methods. The goal was to categorize projects in such a way that systems engineers and HSI practitioners could leverage tools, processes, and lessons learned across projects (Handley 2019b).
The original framework was developed by a team of Army HSI practitioners and subject matter experts (SMEs). The HSE framework was part of a larger project designed to mitigate human performance shortfalls and maximize system effectiveness by integrating well‐defined HSE (and where applicable HSI) processes and activities into the acquisition life cycle and to make these analyses explicit to stakeholders to increase “buy‐in” early in the design process (Taylor 2016). The resulting ontology could be expanded as needed to provide a common framework to identify elements and relationships important to the application of HSE, including classifying different stakeholders, system types, acquisition timelines, and user needs. This would allow HSI practitioners, systems engineers, and program managers to determine appropriate tools, methodologies, and information. The overall goal was to provide an overall organizing structure for HSE processes and products relevant to the SE effort that could be linked to a comprehensive repository of information and concurrent and past projects (Taylor 2016).
The original HSE framework is shown in Figure 1.1; it is a subset of the envisioned comprehensive ontology. This framework was used successfully to categorize different projects that involved the intersection of SE and HSI, including the Army’s transition to cross‐functional teams (Handley 2018). The framework represents the initial effort to provide a consistent taxonomy to determine appropriate tools and methodologies to address sociotechnical system concerns by offering an organizing structure to identify similar efforts.
Figure 1.1 HSE original framework.
The dimensions and descriptions of the original framework are as follows:
1 Sociotechnical system type – This dimension represents the different ways that users interact with systems. From the “users are the system,” which represents organizations