The Function-Behaviour-Structure ontology – or short, the FBS ontology – is an ontology of design objects, i.e. things that have been or can be designed. The Function-Behaviour-Structure ontology conceptualizes design objects in three ontological categories: function (F), behaviour (B), and structure (S). The FBS ontology has been used in design science as a basis for modelling the process of designing as a set of distinct activities. This article relates to the concepts and models proposed by John S. Gero and his collaborators. Similar ideas have been developed independently by other researchers.[1][2][3]
The ontological categories composing the Function-Behaviour-Structure ontology are defined as follows:[4][5]
The three ontological categories are interconnected: Function is connected with behaviour, and behaviour is connected with structure. There is no connection between function and structure.
The Function-Behaviour-Structure ontology is the basis for two frameworks of designing: the FBS framework, and its extension, the situated FBS framework. They represent the process of designing as transformations between function, behaviour and structure, and subclasses thereof.
The original version of the FBS framework was published by John S. Gero in 1990.[6] It applies the FBS ontology to the process of designing, by further articulating the three ontological categories. In this articulation, behaviour (B) is specialised into expected behaviour (Be) (the "desired" behaviour) and behaviour derived from structure (Bs) (the "actual" behaviour). In addition, two further notions are introduced on top of the existing ontological categories: requirements (R) that represent intentions from the client that come from outside the designer, and description (D) that represents a depiction of the design created by the designer. Based on these articulations, the FBS framework proposes eight processes claimed as fundamental in designing,[4][7] specifically:
The eight fundamental processes in the FBS framework are illustrated using a turbocharger design process.
The situated FBS framework was developed by John S. Gero and Udo Kannengiesser in 2000[7] as an extension of the FBS framework to explicitly capture the role of situated cognition or situatedness in designing.[8][9]
The basic assumption underpinning the situated FBS framework is that designing involves interactions between three worlds: the external world, the interpreted world and the expected world. They are defined as follows:[4][5][7]
The three worlds are interconnected by four classes of interaction:
The situated FBS framework is a result of merging the three-world model of situatedness with the original FBS framework, by specialising the ontological categories as follows:[4][5][7]
20 processes connect these specialised ontological categories. They elaborate and extend the eight fundamental processes in the FBS framework, providing more descriptive power with regards to the situatedness of designing.
The FBS ontology has been used as a basis for modelling designs (the results of designing) and design processes (the activities of designing) in a number of design disciplines, including engineering design, architecture, human-computer interface, human-robot interface, construction and software design.[11][12][13][14][15][16][17][18][19] While the FBS ontology has been discussed in terms of its completeness,[20][21][22][23] several research groups have extended it to fit the needs of their specific domains.[24][25][26][27][28][29][30][31] It has also been used as a schema for coding and analysing behavioural studies of designers.[32][33][34][35][36]
Others have applied the FBS ontology to develop an ontology of systems.[31][19][37] For this purpose, the three categories of concepts (i.e., Function, Behavior, Structure) are expanded to be six categories of concepts by adding the concepts of Context, Principle, State. As such, the FBS ontology becomes the FCBPSS ontology. In the FCBPSS ontology, the definition of Function and Structure remains the same as that in the FBS ontology. The concepts of Behavior, Context, Principle, and State are as follows.
The six categories of concepts are related, especially the structure of a system is a foundation, followed by the state, behavior, and function. The principle aggregates states along with their underlying structure to the behavior of the structure.