Definition MBSE Model
What is a model respectively an MBSE model? It seems to be an easy question on the first view. Of course, we would, for example, call a SysML model an MBSE model. Typically, a text document is not classified as a model. But what are the criteria that declassified the text document?
That is my test case for the definition: The definition clearly classifies a text document and a spreadsheet not as an MBSE model, but a SysML model and a Modelica model.
I know there are more model types and I don’t have 100% test coverage.
Let’s start with the general definition of a model.
A model is a representation of an object created using abstraction.
This is the typical definition of a model, which can be found in many places in different words, for example, in ISO standards. The word “object” here is used in the broadest sense. It can be a thing, a person, a concept, a system, and so on. Abstraction is the process of omitting details as necessary and transferring the object of interest to something more general.
The definition is correct, but it does not satisfy my test case. A text document that describes a system is also a representation of it. It represents it and reduces the mapping to essential features.
My definition of the “MBSE Model” is as follows
An MBSE Model is a model that represents systems and their environments and is based on a modeling language that covers concepts of systems engineering.Tim Weilkiens
The first part includes the common definition of a model (“An MBSE Model is a model”). The second, in other words, means that the systems engineering semantics is part of the modeling language and thus accessible for machines.
If a machine is reading a spreadsheet and in a cell, there is the number 42, then the machine only knows that it is the number 42. About the cell format possibly still whether it is an integer, real, or a currency. A human could probably read more out of the spreadsheet because the number 42 is in a column with the heading “mass” and in a neighboring column, that it is about part X. A machine has no access to this information because the model behind the spreadsheet does not cover systems engineering concepts.
If a machine reads a SysML model and a value property has the value 42, then the machine can also learn the unit and quantity kind of the value. The value property belongs to a part X, which is embedded in a system hierarchy, and so on. Concepts of systems engineering are part of the model.