While considering all classes of systems, SE focuses on the domain of the engineered systems (ES). Socio technical systems are treated as a special form of engineered system. There are differences and commonalities in scope of the three overall categories of systems — engineered, natural, and social. For example, power generation and distribution systems are purely engineered systems which include software and human operators as well as hardware. Water and power safety legislation comes from the political processes of a legislature, which is a social system. The resulting water and power safety assurance and safety governance systems are sociotechnical systems whose participants work in both engineered systems and social systems.
The nature of and relationships between these system domains is discussed in Part 2, which considers the general nature and purpose of systems and how these ideas are used to ensure a better ES. Part 2 covers:
• Systems Thinking – a way of understanding complex situations by looking at them as combinations of systems
• Systems Science – a collection of disciplines that have created useful knowledge by applying systems thinking and the scientific method to different aspects of the system domains
• Systems Approach – a way of tackling real world problems which uses the tools of system science to enable systems to be engineered and used
One must understand both natural and sociotechnical systems to identify and scope the engineering of system problems or opportunities. This scoping largely determines whether engineered systems achieve their goals, without adverse impact on other outcomes, when those systems are deployed in the real world.
Scope of Systems Engineering within the Engineered Systems Domain
The scope of SE does not encompass the entire ES domain. Activities can be part of the SE environment, but other than the specific management of the SE function, not considered to be part of SE. Examples include system construction, manufacturing, funding, and general management. This is reflected in the International Council on Systems Engineering (INCOSE) top-level definition of systems engineering as, “an interdisciplinary approach and means to enable the realization of successful systems.” (INCOSE 2012) Although SE can enable the realization of a successful system, if an activity that is outside the scope of SE, such as manufacturing, is poorly managed and executed, SE cannot ensure a successful realization.
Again, a convenient way to define the scope of SE within the ES domain is to develop a Venn diagram. There is a relationship between SE, system implementation, and project/systems management. Activities, such as analyzing alternative methods for production, testing, and operations, are part of SE planning and analysis functions.
Such activities as production line equipment ordering and installation, and its use in manufacturing, while still important SE environment considerations, stand outside the SE boundary. System implementation engineering also includes the software production aspects of system implementation. Software engineering, then, is not considered a subset of SE.
Traditional definitions of SE have emphasized sequential performance of SE activities, e.g., “documenting requirements, then proceeding with design synthesis …”. (INCOSE 2012) The SEBoK authors depart from tradition to emphasize the inevitable intertwining of system requirements definition and system design in the following revised definition of SE:
Systems Engineering (SE) is an interdisciplinary approach and means to enable the realization of successful systems. It focuses on holistically and concurrently understanding stakeholder needs; exploring opportunities; documenting requirements; and synthesizing, verifying, validating, and evolving solutions while considering the complete problem, from system concept exploration through system disposal. (INCOSE 2012, modified)