Modelling (pre-)Design Activities With a Multi-Stakeholder Perspective - Principia Designae: Pre-Design, Design, and Post-Design - page 173

Fig. 12.2 A schematic representation of the ten main processes of designing in the Extended FBS
model. The bold symbols refer to the variables and processes proposed by the authors
By introducing Needs and Requirements, the Formulation phase proposed in the
original FBS framework must be reviewed in terms of those processes that defin-
itively substitute the direct processes from the external word of R variables to the
interpreted word of F i ,S i , and B i variables (e.g., Processes 1, 2, 3 and 18 in
Fig. 12.1 , right), which leads to the definition of two further phases: Needs
Identification and Requirements Definition.
Overall, the design process thus consists of ten, rather than eight main processes,
as depicted in Fig. 12.2 .
It is interesting to notice that Gero's classification in terms of an external world,
an interpreted world and an expected world still remains useful to “situate” Needs
and Requirements as well. The new classes of variables, N and R, are subjected to
the same transitions proposed in the original FBS model. This means that the
extended FBS situates the new variables in the three worlds of the FBS framework,
which produces the following: N e ,N i , Ne i ,R e ,R i and Re i .
With respect to the above-mentioned work by Ericson et al. ( 2009 ) where
customers and developers' contexts are dealt with separately, the adoption of
Gero and Kannengiesser's “situatedness” allows for explicit representation of the
links among these different worlds. Therefore, the proposed extension of the FBS
framework allows for the description of processes such as those take place in “co-
design” and “user-centered design” activities, which could not properly be
modelled in the original framework.
12.4.1 Needs Identification
Needs identification is one of the two major steps that enrich the original situated
FBS framework. As shown in Fig. 12.3a , the proposed extended model describes
Needs Identification as constituted by three elementary processes: