Lead Authors: Mike Henshaw, Judith Dahmann, Bud Lawson Show
System of systems engineering (SoSE) is not a new discipline; however, this is an opportunity for the systems engineering community to define the complex systems of the twenty-first century (Jamshidi 2009). While systems engineering is a fairly established field, SoSE represents a challenge for the present systems engineers on a global level. In general, SoSE requires considerations beyond those usually associated with engineering to include socio-technical and sometimes socio-economic phenomena. TopicsEach part of the SEBoK is divided into knowledge areas (KAs), which are groupings of information with a related theme. The KAs in turn are divided into topics. This KA contains the following topics:
Characteristics and Definitionof Systems of SystemsMaier (1998) postulated five key characteristics (not criteria) of SoS: operational independence of component systems, managerial independence of component systems, geographical distribution, emergent behavior, and evolutionary development processes, and identified operational independence and managerial independence as the two principal distinguishing characteristics for applying the term 'systems-of-systems.' A system that does not exhibit these two characteristics is not considered a system-of-systems regardless of the complexity or geographic distribution of its components. In the Maier characterization, emergence is noted as a common characteristic of SoS particularly in SoS composed of multiple large existing systems, based on the challenge (in time and resources) of subjecting all possible logical threads across the myriad functions, capabilities, and data of the systems in an SoS. As introduced in the article Emergence, there are risks associated with unexpected or unintended behavior resulting from combining systems that have individually complex behavior. These become serious in cases which safety, for example, is threatened through unintended interactions among the functions provided by multiple constituent systems in a SoS. ISO/IEC/IEEE 21839 (ISO, 2019) provides a definition of SoS and constituent system:
In addition, there are several definitions of system(s) of systems (SoS), some of which are dependent on the particularity of an application area (Jamshidi, 2005). It should be noted that formation of a SoS is not necessarily a permanent phenomenon, but rather a matter of necessity for integrating and networking systems in a coordinated way for specific goals such as robustness, cost, efficiency, etc. The US DoD (2008) defines Systems of Systems Engineering as “planning, analyzing, organizing, and integrating the capabilities of a mix of existing and new systems into an SoS capability greater than the sum of the capabilities of the constituent parts”. ISO/IEC/IEEE 15288 Annex G (2015) also describes the impact of these characteristics on the implementation of systems engineering processes. Because of the independence of the constituent systems, these processes are in most cases implemented for engineering both the systems and the system of systems and need to be tailored to support the characteristics of SoS. These processes are shown in the table below highlighting the fact that these processes are implemented at both the system and SoS levels, with SoSE often constrained by the systems. Table 1. Differences Between Systems and Systems of Systems as They Apply to Systems Engineering.
Finally, based on work done by the INCOSE Systems of Systems Work Group (Dahmann, 2014), the major challenges facing SoSE have been catalogued in terms of seven pain points. These challenges are presented in the SoSE section of the INCOSE SE Handbook. (INCOSE 2015). These challenges include:
Types of SoSIn today’s interconnected world, SoS occur in a broad range of circumstances. In those situations where the SoS is recognized and treated as a system in its right, an SoS can be described as one of four types (Maier, 1998; Dahmann and Baldwin, 2008, ISO 21839, 2019):
This taxonomy is based on the degree of independence of constituents and it offers a framework for understanding SoS based on the origin of the SoS objectives and the relationships among the stakeholders for both the SoS and its constituent systems. In most actual cases, an SoS will reflect a combination of SoS types which may change over time. This taxonomy is in general use. It is presented in 15288 Annex G and in ISO 21841, "Taxonomy of Systems of systems". Other taxonomies may focus on nature/type of components, their heterogeneity, etc. (Cook, 2014) As noted above, many SoS exist in an unrecognized state; this is increasingly true as the levels of interconnectivity between modern systems keeps increasing. Kemp et al (2013) describe such systems as “accidental” but they can be described as “discovered” (Dahmann and Henshaw, 2016) because it is only when they become significant for some reason that we recognize them, at which point they can usually fall into one of the above four categories, since their significance means they must now operate, with management, in some defined way. From the SoSE point of view, another potential classification would consider the level of anticipation/preparation of SoSE with respect to SoS operations and level of stability of the SoS objectives; this is referred to as variability by Kinder et. al. (2012). This could range from an SoS which responds to a particular trigger and is put immediately in place when needs are expressed. An example of such an SoS would be a crisis management SoS. This type of SoS is updated dynamically during the operation. At the other end of the spectrum there are well-specified and stable SoS developed to answer to specified ongoing needs. An example of such a persistent SoS is an air traffic management system. This type of SoS is acquired and qualified in a well-defined environment and any need for evolution will imply a formal SE evolution and re-qualification. While much of the early attention to SoS has focused on Acknowledged SoS where current SE practices can be adapted and applied, there is an increasing recognition that the predominance of SoS exist in the collaborative and virtual types (Honour 2016), and in those areas where SoS may not be officially recognized but affect many of the broader capabilities in today’s interconnected world. In these cases, the focus is shifting to understanding SoS as socio-technical, complex adaptive systems rather than extensions of current technical systems with a focus on understand and addressing the inherent complexity of these types of SoS. SoSE Application DomainsApplication of SoSE is broad and is expanding into almost all walks of life. Originally identified in the defense environment, SoSE application is now much broader and still expanding. The early work in the defense sector has provided the initial basis for SoSE, including its intellectual foundation, technical approaches, and practical experience. In addition, parallel developments in information services and rail have helped to develop SoSE practice (Kemp and Daw, 2015). Now, SoSE concepts and principles apply across other governmental, civil and commercial domains. Some examples include:
Increased networking and interconnectedness of systems today contributes to growth in the number and domains where SoS are becoming the norm, particularly with the considerable converge among systems of systems, cyber-physical systems and the internet of things. (Henshaw, 2016). Difference between System of Systems Engineering and Systems EngineeringObservations regarding differences between individual or constituent systems and SoS are listed in Table 1. These differences are not as black and white as the table might suggest and in each case, the degree of difference varies in practice. Modern systems tend to be highly inter-connected, so that the assumptions that lead to the characteristics of Systems Engineering in Table 2 are less frequently met.
It is the characteristics of management and operational independence (Maier,1998) that most fundamentally distinguishes the behavior of SoS from unitary systems: this has been explained by Rebovich (2009) as the fundamental problem for SoS : From the single-system community’s perspective, its part of the SoS capability represents additional obligations, constraints and complexities. Rarely is participation in an SoS seen as a net gain from the viewpoint of single-system stakeholders [Rebovich, 2009]. SoSE StandardsThe first standards for system of systems engineering have been adopted by the International Standards organization. These were initiated in 2016 response to the report of an ISO SoS Standards study group (ISO, 2016) recognizing the increased attention to SoS and the value to standards to the maturation of SoSE. Three standards were adopted in 2019 (INCOSE 2020):
This standard provides a set of critical considerations to be addressed at key points in the life cycle of systems created by humans and refers to a constituent system that will interact in a system of systems as the system of interest (SOI). These considerations are aligned with ISO/IEC/IEEE 15288 and the ISO/IEC/IEEE 24748 framework for system life cycle stages and associated terminology.
This standard provides guidance for the utilization of ISO/IEC/IEEE 15288 in the context of SoS. While ISO/IEC/IEEE 15288 applies to systems (including constituent systems), this document provides guidance on application of these processes to SoS. However, ISO/IEC/IEEE 21840 is not a self-contained SoS replacement for ISO/IEC/IEEE 15288. This document is intended to be used in conjunction with ISO/IEC/IEEE 15288, ISO/IEC/IEEE 21839 and ISO/IEC/IEEE 21841 and is not intended to be used without them.
The purpose of this standard is to define normalized taxonomies for systems of systems (SoS) to facilitate communications among stakeholders. It also briefly explains what a taxonomy is and how it applies to the SoS to aid in understanding and communication. ReferencesWorks CitedCook, S. C. and Pratt, J. M., “Towards designing innovative SoSE approaches for the Australian defence force,” Proc. 9th Int. Conf. Syst. Syst. Eng. Socio-Technical Perspect. SoSE 2014, pp. 295–300, 2014. Dahmann, J, and M.J.D Henshaw. 2016. “Introduction to Systems of Systems Engineering”, INCOSE INSIGHT, October 2016, Volume 19, Issue 3, pages 12-16. Dahmann, Judith. 2015. Systems of Systems Pain Points, INCOSE International Symposium, Seattle, WA. Dahmann, J., and K. Baldwin. 2008. "Understanding the Current State of US Defense Systems of Systems and the Implications for Systems Engineering." Presented at IEEE Systems Conference, April 7-10, 2008, Montreal, Canada. DoD. 2008. Systems Engineering Guide for Systems of Systems. Arlington, VA: US Department of Defense, Director, Systems and Software Engineering, Deputy Under Secretary of Defense (Acquisition and Technology), Office of the Under Secretary of Defense (Acquisition, Technology and Logistics). Accessed 2 /26/2022. Available: https://acqnotes.com/wp-content/uploads/2014/09/DoD-Systems-Engineering-Guide-for-Systems-of-Systems-Aug-2008.pdf Henshaw, M.J.d,, “Systems of Systems. Cyber-Physical Systems, the Internet of Things… Whatever Next?” INCOSE INSIGHT, October 2016, Volume 19, Issue 3, pages 51-54. Honour, E.., "Engineering the Virtual or Collaborative SoS", INCOSE INSIGHT, October 2016, Volume 19, Issue 3, pages 67-69. INCOSE, 2020. Systems of Systems Standards Quick reference Guide, INCOSE -2020 -sosstandards. INCOSE, 2018. Systems of Systems Primer, INCOSE-TP-2018-003-01.0. INCOSE SE Handbook. 2015 International Organization for Standardization (ISO). 2019. ISO/IEC/IEEE 21839 —Systems and Software Engineering—System of systems considerations in life cycle stages of a system. International Organization for Standardization (ISO). 2019. ISO/IEC/IEEE 21840 —Guidelines for the utilization of ISO/IEC/IEEE 15288 in the context of system of systems. International Organization for Standardization (ISO). 2019. ISO/IEC/IEEE 21481 —Systems and Software Engineering—Taxonomy of systems of systems. International Standards Organization, 2016. Report of the SC7 SG on Systems of Systems Engineering. International Organization for Standardization (ISO). 2015. ISO/IEC/IEEE 15288—Systems and Software Engineering—System life cycle processes. Jamshidi, M. (ed). 2009a. Systems of Systems Engineering – Innovations for the 21st Century. Hoboken, NJ, USA: Wiley. Jamshidi, Mo. (2005). System-of-Systems Engineering-a Definition. Kemp, D., et. al.. 2013. Steampunk System of Systems Engineering: A case study of successful System of Systems engineering in 19th century Britain." Presented at INCOSE International Symposium, June 24–27, 2013, Philadelphia, PA. Kinder, A., Barot, V., Henshaw, M., & Siemieniuch, C. (2012). System of Systems: “Defining the system of interest.” In Proc. 7th Int. Conf. Systems of Systems Eng., Genoa, italy (pp. 463–468). Retrieved from http://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber=6384211 Maier, M.W. 1998. "Architecting Principles for Systems-of-Systems." Systems Engineering. 1 (4): 267-284. Rebovich Jr., G. 2009. "Chapter 6: Enterprise System of Systems," in Systems of Systems Engineering - Principles and Applications. Boca Raton, FL, USA: CRC Press. Primary ReferencesDahmann, J., and K. Baldwin. 2008. "Understanding the Current State of US Defense Systems of Systems and the Implications for Systems Engineering." Presented at IEEE Systems Conference, April 7-10, 2008, Montreal, Canada. DoD. 2008. Systems Engineering Guide for Systems of Systems, version 1.0. Washington, DC, USA: US Department of Defense (DoD). Available: http://www.acq.osd.mil/se/docs/SE-Guide-for-SoS.pdf. INCOSE Systems Engineering Handbook, 4th Edition, John Wiley & Sons Inc., 2015 International Standards Organization, 2016. Report of the SC7 SG on Systems of Systems Engineering. Jamshidi, M. (ed). 2009a. Systems of Systems Engineering – Innovations for the 21st Century. Hoboken, NJ, USA: Wiley. Maier, M.W. 1998. "Architecting Principles for Systems-of-Systems." Systems Engineering. 1 (4): 267-284. Additional ReferencesBarot, V., S. Henson, M. Henshaw, C. Siemieniuch, M. Sinclair, S.L. Lim, M. Jamshidi, and D. DeLaurentis. 2012. Trans-Atlantic Research and Education Agenda in Systems of Systems (T-AREA-SoS) SOA Report. Longborough, England, UK: Longborough University. Ref. TAREA-RE-WP2-R-LU-7. Boardman, J., and B. Sauser. 2006. "System of Systems - the Meaning of Of." IEEE Conference on Systems of Systems Engineering, April 24-26, 2006, Los Angeles, CA. Carlock, P., and J.A. Lane. 2006. System of Systems Enterprise Systems Engineering, the Enterprise Architecture Management Framework, and System of Systems Cost Estimation. Los Angeles, CA, USA: Center for Systems and Software Engineering (CSSE), University of Southern California (USC). USC-CSE-2006-618. Checkland, P.B. 1999. Systems Thinking, Systems Practice. Chichester, UK: John Wiley & Sons Ltd. Dahmann, J., Rebovich, G., Lane, J., Lowry, R. & Baldwin, K. 2011. "An Implementer's View of Systems Engineering for Systems of Systems." IEEE Systems Conference, April 4-7, 2011, Montreal, Canada. p. 212-217. Keating C.B., J.J. Padilla, and K. Adams. 2008. "System of systems engineering requirements: Challenges and guidelines". EMJ - Engineering Management Journal. 20 (4): 24-31. Luzeaux, D., and J.R. Ruault. 2010. Systems of Systems. London, UK: ISTE. MITRE. "System of Systems Engineering Collaborators Information Exchange (SoSECIE) Webinar Archive," MITRE, 2019. Available: [1] Neaga, E.I., M.J.d. Henshaw, and Y. Yue. 2009. "The influence of the concept of capability-based management on the development of the systems engineering discipline." Proceedings of the 7th Annual Conference on Systems Engineering Research, April 20-23, 2009, Loughborough University, Loughborough, England, UK. Poza, A.S., S. Kovacic, and C. Keating. 2008. "System of Systems Engineering: An Emerging Multidiscipline". International Journal of System of Systems Engineering. 1 (1/2). Ring J. 2002. "Toward an ontology of systems engineering." INSIGHT. 5 (1): 19-22. Relevant Videos
< Previous Article | Parent Article | Next Article > SEBoK v. 2.6, released 20 May 2022 What are the characteristics of wellList the characteristics of well-designed service systems.. consistent with the organization mission.. user friendly.. robust if variability is a factor.. Easy to sustain.. Cost-effective.. Value that is obvious to customers.. Which of the following is a characteristic of a wellA characteristic of a well-designed service system is that it manages the evidence of service quality in such a way that customers are aware of the value of the service provided.
Which of the following refers to the physical presence of the customer in a service system?To elaborate, customer contact refers to the physical presence of the customer in the system, and creation of the service refers to the work process that is entailed in providing the service itself.
Which of the following is a major factor that distinguishes service design and development from manufacturing design and development?Which of the following is a major factor that distinguishes service design and development from manufacturing design and development? The service package is the major output of the development process.
|