Modelling (pre-)Design Activities With a Multi-Stakeholder Perspective - Principia Designae: Pre-Design, Design, and Post-Design - page 170

processes. An extensive survey of these models is proposed in Wynn and
Clarkson ( 2005 ) .
Among the applications of the descriptive models, it is worth mentioning their
use within design protocol analyses as a means to analyse the design activities of
individuals and teams, so as to identify typical patterns and behaviours (e.g.,
(Bierhals et al. 2007 ) ), as well as to evaluate the impact of training activities
(as in (Gero et al. 2012 )). Besides, as discussed above, none of those models allows
mapping, and thus studying, what concerns needs identification and the definition of
the design specification.
With the aim of addressing such a gap, the authors decided to build on a well-
acknowledged existing model, rather than creating a dedicated new one. This
choice has several motivations: first, an extension of a well-known model is
expected to be easier to understand and to be adopted by other scholars. Second,
it allows leveraging the advantageous research experiences conducted so far by the
design community. Eventually, an extended model, rather than a dedicated one, is
intrinsically suitable for analysing the entire design process, and not just the earliest
stages of new product development, therefore with a much wider spectrum of
potential exploitations.
An acknowledged model for representing design cognitive processes is the
situated FBS framework (Gero and Kannengiesser 2004 ) , which has all the features
to be extended according to the proposed objectives. Besides, since its first formu-
lation in 1990 (Gero 1990 ), the FBS framework has been already evolved both by
his main author and by other scholars, so as to extend its applicability to diverse
contexts.
The FBS model considers three classes of variables as the object of the design
activities:
• Functions (F), which describe the aim of the object, i.e., what the object is for;
• Structures (S), which describe the object components and their relationships, i.e.,
what the object is; and
• Behaviours (B), which describe the attributes that are derived or expected to
result from the structure (S) variables of the object, i.e., what the object does.
These variables undergo eight reference processes (Fig. 12.1 , left); five of them
convert the posited functions sequentially into design descriptions. The first is
called the formulation step and transforms functions F into a description of behav-
iour Be of an artefact that is expected to perform the previous functions. Then, the
expected behaviour is transformed by a synthesis step into a structure S of the
artefact by which it may show its behaviour Be. Subsequently, in a third step, called
analysis, the actual behaviour Bs of the artefact with this structure S is derived.
Fourthly, this actual behaviour is evaluated by comparing it with the expected
behaviour. If this evaluation is satisfactory, a design description D is documented
for manufacturing the artefact with the structure S. If the evaluation is not satisfac-
tory, the design process returns to previous steps, defining three elementary loop-
back stages and defining the design process as an iterative procedure.