Alternative options for the main types of system partitioning
Functional objects, constructive elements, locations, and parts of the total cost of ownership are not the only way to see parts in the system. There are a huge number of ways to do this.
Historically, in different schools of thought, system parts were identified very differently:
- ISO 15926 - two main kinds of parts: functional objects, physical objects. The rest can be introduced as needed.
- IEC 81346-1:2022 - "at least" five (function, product and component as custom product, place, type as an arbitrary grouping by some properties, and "other" - where anything else can be included). In our course, we mainly rely on this option, adding recently emerged cost as "other" without specifically distinguishing the "grouping by type" - it is essentially indistinguishable from "other" (and the standard suggests making an agreement for "type" and "other" so the team understands what was chosen).
- Kosyakov, Svita, Seymour's book "Systems Engineering. Principles and Practice" - functional element, component in the sense of a "module".
- SMD methodology - five (processes, elements and connections, external functions, morphology, material).
- ...and so on - examples of different options for enterprise system architecture, with an average of 3-7 main aspects (although "aspects" are also referred to differently everywhere: structural aspects, types/divisions) in different schools of system thinking. And everywhere it is noted that this is "at least", meaning that it recognizes that only the main options that cannot be ignored are being considered. There can be many divisions, they are made as needed, in different projects. But the main divisions are made in all projects.
In our course, we will follow IEC 81346-1:2022, which states that systems have three aspects - functional, constructive, and locations, adding a fourth aspect: cost, as is customary in the rapidly gaining momentum approach of digital twins, and we continue with "these four - the minimum number of aspects/criteria of division." In a project, objects can be further grouped based on arbitrary characteristics as "type aspects," and the standard introduces an aspect of "other" where administrative, logistical, and other groupings can be provided as needed in the project.
Also, it is important to note that a candidate for the next "mandatory" division, not yet included in standards as mandatory but increasingly common in real projects, is the work breakdown structure from project management. It is needed to easily connect the breakdown of products with the breakdown of work and verify that each work is associated with a product, and there are no products without work or work without products.
In the SNC-Lavalin's 8D digital twin experience presentation from the June 2020 digital twins conference, 8 aspects are listed, where D stands for dimension, highlighting the fact that the system exists as an object in many dimensions. This is essentially the same as what was discussed a decade ago in product lifecycle management (PLM), but today the focus is on digital twins, rather than PLM, as emphasis is not only on creating a system but also on its operation. Therefore, engineering data is supplemented with asset data, and the ultimate goal is autonomous operation based on a "single source of truth," i.e., the digital twin as a model of the system that supports consistent descriptions of both the target system in its operational environment and the creating system:
- 1D metadata, documentation (texts)
- 2D drawings ('native files' from CAD)
- 3D information models (representations of the physical form/geometry/layout of the system with material and other characteristics specified)
- 4D 'videoroll' of construction/assembly over time
- 5D resources, material status/cost
- 6D operation, real-time data
- 7D live streaming of the working system and its environment
- 8D analytics, machine learning predictions
So, to remember: there are always more than four aspects/criteria for dividing into parts, and even these four divisions can be complexly organized internally. System parts are usually intertwined and can be considered hybrids. Systems thinking recommends untangling hybrid descriptions and restoring the initial objects of interest/important characteristics.
Often hybrids arise because a product division at one system level is suddenly modeled functionally, "jumping between times" - development-time division suddenly continues as an operations-time division. It is necessary to track this. Or a placement division (for example, dividing a house by floors) suddenly turns into a product/constructive division on the next level (breaking down by equipment units on the floor). Or an engineering document suddenly turns into a summary procurement specification, with procurement prices taking precedence. Is this permissible? It is, if you understand what you are doing. If not completely sure, it would be better not to proceed.
For different roles in the project, the system will be represented in its different aspects/perspectives partially, following the method of one or another division option, but in systemic transdisciplinary thinking, it remains holistic of all its aspects/elements. Parts of the system are highlighted in the physical system by attention, it is just that this attention is structured differently. The difference in system divisions for one system - is simply the result of different criteria for selecting parts with attention!