Think-in-Systems
An intuitive Introduction to Systems Engineering and Dynamics
Project maintained by sohamphanseiitb Hosted on GitHub Pages — Theme by mattgraham
System Hierarchy
For the ease of analysis and organization, systems are divided into subsystems, components and parts. Sometimes multiple systems are combined together to form a System of Systems. Let us see what these mean, one by one.
What is a Subsystem?
A subsystem is a set of interacting components which perform a function but aren’t relevant on their own i.e they don’t accomplish an objective on their own. The definition is quite similar to that of a system but there’s a thin boundary separating the two.
Let me quote the example of an automobile. The automobile as a whole is a system, since it has a set of components like the engine, interior, braking mechanism, fuel tank, carbeurator, compressor which interact with each other and accomplish the objective of transporting matter from one point to another.
On the other hand, the engine which powers the automobile also has several interacting components like the piston assembly, igniters, compressors and it performs the function of power generation. However, on its own it is of little use, since with raw power, things can’t be transported but we need external support like powertrain, wheels to be installed. Hence the engine is a subsystem.
What is a System of Systems?
A System of Systems is again a system, but a special one, since some (in some cases, all) of its components are systems themselves, meaning each of them has its own independent function/purpose and existence.
For instance, consider the Air Transportation System. Mind you, I don’t mean an aircraft here. An Air transportation system comprises of aircrafts, airports, air traffic control centres, maintainance centres, equipment, personnel and a whole lot of other things. If you think closely, some of them are systems in themselves, the airport is a system since it has many interacting components like ATC, cargo unit, maintainance units and performs the function of smooth air transportation and control.
As a rule of thumb, it is recommended that you decompose a system into not more than 5 to 7 subsystems. However, this rule can be overruled if the system organization needs more subsystems on the basis of the functions they all perform.
All in all, we can clearly see that hierarchy and organization in a system is just a way to ease administration and analysis of a system. There aren’t strict rules of how to demarcate systems, but some general guidelines and thumb rules can be used to ease the process.
You now know the basic barebones of a system and how it is divided into subsystems or clubbed in System of Systems. We will next look at the various processes which go on before the successful deployment of a system and not only that, the maintainance and retirement phase of any system. Stay tuned!