Human Systems Integration
Lead Author: Ben Schwartz, Contributing Authors: Guy Boy, Alice Squires, Paul Phister, Stuart Booth, Dick Fairley
Human systems integration (HSI) is “the management and technical discipline of planning, enabling, coordinating, and optimizing all human-related considerations during system design, development, test, production, use and disposal of systems, subsystems, equipment and facilities.” (SAE, 2019). Though used by industries around the world, HSI was initiated by the U.S. Department of Defense as part of the “total system approach” to acquisition. The goal of HSI is to “optimize total system performance (hardware, software, and human), operational effectiveness, and suitability, survivability, safety, and affordability.” (DoD, 2003) HSI activities must be initiated “early in system development (during stakeholder requirements generation) and continuously through the development process to realize the greatest benefit to the final system solution and substantial lifecycle cost savings.” (INCOSE Systems Engineering Handbook, 2015).
HSI generally incorporates the following domains as integration considerations: manpower, personnel, training, human-centered design, human factors engineering, life-critical systems that include occupational health, environment, safety, habitability, and human survivability. Some organizations use a slightly different domain set.
- 1 Overview
- 2 System Description
- 3 Discipline Management
- 4 Discipline Relationships
- 5 Discipline Standards
- 6 Personnel Considerations
- 7 Metrics
- 8 Models
- 9 Tools
- 10 Practical Considerations
- 11 References
Historically, insufficient systems engineering resources were dedicated to ensuring proper integration of humans with the rest of the system. Most projects were technology-centered with human considerations being addressed through training. Technological systems were hard to use and maintain, resulting in large manpower and training costs, reduced system performance, and increased risk of catastrophic loss, among other impacts. The U.S. Army was among the first to address this with the Manpower and Personnel Integration (MANPRINT) program in 1986. MANPRINT emphasized the consideration of the HSI domains throughout the system acquisition as a standard part of the systems engineering effort. The approach has since been adopted by the broader U.S. Department of Defense, by international militaries, and by civilian government agencies around the world. (Booher, 2003). Some organizations, particularly the U.K. Ministry of Defence, use the term Human Factors Integration (HFI). HSI applies systems engineering processes, tools, and techniques to ensure that human considerations are given proper weight in all system development activities. HSI should not be confused with Human Factors Engineering (HFE); HFE is a domain of HSI focusing on designing human interfaces. HSI is about mutual integration of technology, organizations and people.
HSI is more than human factors, human-computer interaction, or systems engineering. It is an technical and managerial set of processes that involves the consideration and integration of multiple domains. In addition, HSI involves complexity analysis and organization design and management. Various organizations represent the HSI domains differently as the number and names of the domains are aligned with existing organizational structures. Booher (2003) presents the seven US Army domains. The Canadian Forces have a different number of domains while the UK Ministry of Defence has another. All the technical work of the domains is present while the number and names and the domains is the same. According to the Defense Acquisition University, the HSI domains are:
Manpower: Manpower describes the number and mix of personnel required to carry out a task, multiple tasks, or mission in order to operate, maintain, support, and provide training for a system. Manpower factors are those variables that define manpower requirements. These variables include job tasks, operation/maintenance rates, associated workload, and operational conditions (e.g., risk of operator injury) (DAU 2010).
Environment: Environment includes the physical conditions in and around the system, as well as the operational context within which the system will be operated and supported. Environmental attributes include temperature, humidity, noise, vibration, radiation, shock, air quality, among many others. This "environment" affects the human's ability to function as a part of the system (DAU 2010).
Habitability: Habitability factors are those living and working conditions that are necessary to sustain the morale, safety, health, and comfort of the user population. They directly contribute to personnel effectiveness and mission accomplishment and often preclude recruitment and retention problems. Examples include: lighting, space, ventilation, and sanitation; noise and temperature control (i.e., heating and air conditioning); religious, medical, and food services availability; and berthing, bathing, and personal hygiene. Habitability consists of those characteristics of systems, facilities (temporary and permanent), and services necessary to satisfy personnel needs. Habitability factors are those living and working conditions that result in levels of personnel morale, safety, health, and comfort adequate to sustain maximum personnel effectiveness, support mission performance, and avoid personnel retention problems (DAU 2010).
Human-centered design: Human-Centered Design (HCD) combines creativity, (from virtual to tangible) agile prototyping, formative evaluation, rigorous demonstration and validation. It is based on design thinking, expertise, experience, organization design and management, advanced interaction media, and complexity analysis, and more specifically by considering human-systems integration using modeling and human-in-the-loop simulation from the very beginning of the design process, as well as during the whole life cycle of a system (Boy, 2017).
Human factors engineering: Human factors engineering is primarily concerned with designing human-machine interfaces consistent with the physical, cognitive, and sensory abilities of the user population. Human-machine interfaces include: •functional interfaces (functions and tasks, and allocation of functions to human performance or automation); •informational interfaces (information and characteristics of information that provide the human with the knowledge, understanding, and awareness of what is happening in the tactical environment and in the system);
- environmental interfaces (the natural and artificial environments, environmental controls, and facility design);
- co-operational interfaces (provisions for team performance, cooperation, collaboration, and communication among team members and with other personnel);
- organizational interfaces (job design, management structure, command authority, and policies and regulations that impact behavior);
- operational interfaces (aspects of a system that support successful operation of the system such as procedures, documentation, workloads, and job aids);
- cognitive interfaces (decision rules, decision support systems, provisions for maintaining situational awareness, mental models of the tactical environment, provisions for knowledge generation, cognitive skills and attitudes, and memory aids); and
- physical interfaces (hardware and software elements designed to enable and facilitate effective and safe human performance such as controls, displays, workstations, worksites, accesses, labels and markings, structures, steps and ladders, handholds, maintenance provisions, etc.) (DAU 2010).
Human survivability: In the defense domain, survivability factors consist of those system design features that reduce the risk of fratricide, detection, and the probability of being attacked, and that enable personnel to withstand man-made hostile environments without aborting the mission, objective, or suffering acute chronic illness, disability, or death. Survivability attributes are those that contribute to the survivability of manned systems (DAU 2010).
Occupational health: Occupational health factors are those system design features that serve to minimize the risk of injury, acute or chronic illness, or disability, and/or reduce job performance of personnel who operate, maintain, or support the system. Prevalent issues include noise, chemical safety, atmospheric hazards (including those associated with confined space entry and oxygen deficiency), vibration, ionizing and non-ionizing radiation, and human factors issues that can create chronic disease and discomfort such as repetitive motion diseases. Many occupational health problems, particularly noise and chemical management, overlap with environmental impacts. Human factors stresses that creating a risk of chronic disease and discomfort overlaps with occupational health considerations (DAU 2010).
Personnel: Personnel factors are those human aptitudes (i.e., cognitive, physical, and sensory capabilities), knowledge, skills, abilities, and experience levels that are needed to properly perform job tasks. Personnel factors are used to develop occupational specialties for system operators, maintainers, trainers, and support personnel (DAU 2010). The selection and assignment of personnel is critical to the success of a system, as determined by the needs set up by various work-related requirements.
Safety: The design features and operating characteristics of a system that serve to minimize the potential for human or machine errors or failure that cause injurious accidents (DAU, 2010). Safety also encompasses the administrative procedures and controls associated with the operations, maintenance, and storage of a system.
Training: Training is the learning process by which personnel individually or collectively acquire or enhance pre-determined job-relevant knowledge, skills, and abilities by developing their cognitive, physical, sensory, and team dynamic abilities. The "training/instructional system" integrates training concepts and strategies, as well as elements of logistic support to satisfy personnel performance levels required to operate, maintain, and support the systems. It includes the "tools" used to provide learning experiences, such as computer-based interactive courseware, simulators, actual equipment (including embedded training capabilities on actual equipment), job performance aids, and Interactive Electronic Technical Manuals (DAU 2010).
In a contractor project organization, the human systems integrator is typically a member of the senior engineering staff reporting to either the systems engineering lead or chief engineer. HSI activities are documented in the Systems Engineering Management Plan (SEMP). Larger programs may have a stand-alone HSI Plan (HSIP) compatible with and referenced by the SEMP. HSI activities are tailored to the needs of the project and the project lifecycle (NASA, 2016). Most projects implement a Joint HSI Working Group between the customer and contractor. This enables sharing of priorities, knowledge, and effort to allow each group to achieve their objectives.
- SE: HSI is an integral part of the systems engineering effort and the integrator participates in all relevant systems engineering activities during the whole life cycle of the system being considered.
- HSI domain experts: Domain experts collaborate with the human systems integrator to achieve HSI objectives, though this may or may not be a direct reporting relationship.
- The contractor and customer may each have a human systems integrator and various domain experts; each role should collaborate with their counterparts to the appropriate extent.
- HSI domain experts may participate in integrated product teams (IPTs)/design teams as full participants or consultants as appropriate for the needs of the project.
- HSI shares many concerns with Reliability, Availability, and Maintainability (RAM). The integrator and/or domain experts may collaborate with RAM specialists as appropriate.
- The integrator and/or domain experts should work with the Test & Evaluation team to ensure that HSI is represented in test and evaluation events.
- HSI shares many concerns with logistics and supportability, the integrator and/or domain experts may collaborate with this team as appropriate.
HSI depends on sufficient scope of work and authorization from the project. Proper planning and leadership buy-in is a key enabler.
Note: These are standards relevant to the practice of HSI specifically and not each of the HSI domains, which have their own standards and practices.
- National Aeronautics and Space Administration (NASA). 2015. Human Systems Integration Practitioner’s Guide. NASA/SP-2015-3709. Houston: Johnson Space Center.
- SAE International. 2019. Standard Practice for Human Systems Integration. SAE6906. Warrendale, PA: SAE International.
- U.K. Ministry of Defence. 2016. Defence Standard 00-251: Human Factors Integration for Defence Systems. Glasglow: Defence Equipment and Support.
- U.S. Army. 2015. Regulation 602-2: Human Systems Integration in the System Acquisition Process. Washington: Headquarters, Department of the Army.
- U.S. Department of Defense. 2011. Data Item Description: Human Systems Integration Program Plan. DI-HFAC-81743A.
- U.S. Navy. 2017. Opnav Instruction 5310.23A: Navy Personnel Human Systems Integration. Washington: Office of the Chief of Naval Operations: Department of the Navy.
HSI is conducted by a human systems integrator. The integrator is part of the systems engineering team responsible for conducting systems engineering related to human and organizational considerations and for coordinating the work of the HSI domain experts. HSI uses the same techniques and approaches as systems engineering with additional consideration for non-materiel aspects of the system. Therefore, the integrator must be well-versed in the SE process and have a working understanding of each of the domains. The integrator does not need to be an expert in any of the domains. The human systems integrator’s responsibilities include:
- provide inputs to the SEMP and/or create an HSI Plan (HSIP) compatible with the SEMP and the project lifecycle (NASA Systems Engineering Handbook, 2016)
- tailor the scope of HSI efforts to the needs of the project and system lifecycle
- ensure HSI domains are given appropriate consideration across all programmatic and engineering activities
- assist domain personnel in planning domain activities
- facilitate execution of domain tasks and collaboration among domains
- make tradeoffs among domains to optimize the attainment of HSI goals
- optimize the impact of domains on the acquisition program from the perspectives of performance, sustainability, and cost
- integrate the results of domain activities and represent them to the rest of the acquisition program from a total HSI perspective
- facilitate interactions among domains within the scope of HSI, and between HSI and the rest of the program
- track, status, and assess HSI risks, issues and opportunities that have surfaced during the execution of the program
Human-System Measures of Effectiveness
A measure of effectiveness (MOE) is a metric corresponding to the accomplishment of the mission objective. MOEs measure system performance in a representative mission context, including with representative users. Effectiveness is typically achieved through a combination of hardware, software, and human components, thus there are not typically HSI-specific MOEs. MOEs may be decomposed into measures of performance (MOP) and measures of suitability (MOS). There may be HSI-specific MOPs and MOSs. For example, an MOE for an air defense radar might be positive detection probability, with an MOP for the radar’s effective resolution and an MOP for the operator’s ability to identify the target. It is the human system integrator’s responsibility to ensure that relevant MOPs and MOSs are identified and incorporated into modeling, simulation, test, and evaluation efforts. The integrator and domain experts may contribute to these efforts as appropriate.
HSI Process Models
HSI shares common systems engineering models with general systems engineering (e.g. the SE Vee process model). Additionally, a number of HSI-specific models and processes exist. A particularly good resource is A User-Centered Systems Engineering Framework by Ehrhart and Sage (in Booher 2003).
Human Performance and Domain Models
A variety of human performance models exist for cognition, behavior, anthropometry, strength, fatigue, attention, situation awareness, etc. Additionally, a variety of models exist for each HSI domain. The integrator should have a good understanding of the types of models available and the appropriate applications. In a project utilizing model-based systems engineering, the system model should include humans. The integrator should ensure sufficient fidelity to meet the needs of the project. Human-in-the-loop simulations should be encouraged during the design process as during the whole life cycle of a product.
HSI shares common tools with systems engineering. A sample of HSI-specific tools include:
- Command Control and Communications - Techniques for Reliable Assessment of Concept Execution (C3TRACE) developed by U.S. Army Research Labs. https://www.arl.army.mil/www/default.cfm?page=3200
- Comprehensive Human Integration Evaluation Framework (CHIEF) developed by U.S. Navy. http://calhoun.nps.edu/handle/10945/42696
- Human Analysis and Requirements Planning System (HARPS) developed by U.S. Navy Space and Naval Warfare Systems Command. https://www.dau.mil/cop/log/pages/topics/Manpower%20and%20Personnel.aspx
- Human Systems Integration Framework (HSIF) developed by U.S. Air Force. https://www.acq.osd.mil/se/webinars/2015_10_06-SoSECIE-Risser-Lacson-brief.pdf
- Improved Performance and Research Integration Tool (IMPRINT) developed by U.S. Army Research Labs. https://www.arl.army.mil/www/default.cfm?page=3200
Additionally, each HSI domain has specific tools and approaches for their unique efforts considerations.
Many organizations assign a human factors engineer to the human systems integrator role. This can be a mistake if the individual is not well versed in the SE process. Relegating HSI to a “specialty engineering” team deprives the integrator of sufficient scope and authority to accomplish their mission.
Ensure the human systems integrator is a knowledgeable systems engineer with the respect of the other systems engineers and with a good understanding of each of the HSI domains. A human systems integrator should be involved in program planning activities to ensure sufficient budget and schedule. They should be involved in technical planning activities to create sufficient scope in the SEMP/HISPP, identify HSI-related risks and opportunities, recommend HSI trade studies, etc. There is significant overlap and trade space among the HSI domains, therefore the domain experts, led by the integrator, should collaborate throughout the project to optimize the impact of HSI.
None at this time.
Booher, H.R. (ed.). 2003. Handbook of Human Systems Integration. Hoboken, NJ, USA: Wiley.
Boy, G.A. 2017. Human-Centered Design as an Integrating Discipline. Journal of Systemics, Cybernetics and Informatics. International Institute of Informatics and Systemics. Volume 15, Number 1, pp. 25-32. ISSN: 1690-4524.
DAU. 2010. Defense Acquisition Guidebook (DAG). Ft. Belvoir, VA, USA: Defense Acquisition University (DAU)/U.S. Department of Defense (DoD). February 19, 2010.
National Aeronautics and Space Administration (NASA). 2016. NASA Systems Engineering Handbook Rev. 2. https://www.nasa.gov/connect/ebooks/nasa-systems-engineering-handbook
SAE International. 2019. Standard Practice for Human Systems Integration (SAE6906). Warrendale, PA: SAE. https://saemobilus.sae.org/content/sae6906
U.S. Department of Defense (DoD). 2003. DoD Directive 5000.01, The Defense Acquisition System. https://www.esd.whs.mil/Portals/54/Documents/DD/issuances/dodd/500001p.pdf
US Air Force. 2009. Air Force Human Systems Integration Handbook. Brooks City-Base, TX, USA: Directorate of Human Performance Integration. Available at http://www.wpafb.af.mil/shared/media/document/AFD-090121-054.pdf.
None at this time.
Blanchard, B. S., and W. J. Fabrycky. 2011. Systems Engineering and Analysis. 5th ed. Prentice-Hall International series in Industrial and Systems Engineering. Englewood Cliffs, NJ, USA: Prentice-Hall.
Boy, G.A. (2013). Orchestrating Human-Centered Design. Springer, U.K. ISBN 978-1-4471-4338-3.
Helander, Martin, Landauer, T.K, and Prabhu, P.V. 1997. Handbook of Human-Computer Interaction. Amsterdam, Netherlands: Elsevier.
Pew, R.W. and A.S. Mavor. 2007. Human-System Integration in the System Development Process: A New Look. Washington, DC, USA: National Academies Press.
Simpkiss, B. (2009). AFHSIO-001: Human Systems Integration Requirements Pocket Guide. Falls Church, VA: Air Force Human Systems Integration Office.
U.S. Department of Defense (DoD). 2003. DoD Instruction 5000.02, Operation of The Defense Acquisition System.
Wickens, C.D., Lee, J. D, Liu, Y., and Becker, S.E. Gordon. 2004. An Introduction to Human Factors Engineering. Englewood Cliffs, NJ, USA: Prentice-Hall.
Woodson, W.E, Tillman, B. and Tillman, P. 1992. "Human Factors Design Handbook: Information and Guidelines for the Design of Systems, Facilities, Equipment, and Products for Human Use." 2nd Ed. New York, NY, USA: McGraw Hill.