Reflections on the FBS model: proposal for an extension to needs and requirements modeling

The paper proposes an extension of the Function-Behaviour-Structure (FBS) framework in order to represent Needs and Requirements and their relationships with the Function, the Behaviour and the Structure of an artefact. Needs and Requirements are modelled as further types of variables to describe, with the same formal approach of the situated FBS model, the transformation processes, which occur in the earlier stages of design. The suggested model is clarified through an application to the information gathered within an industrial project to reduce water and energy consumption of a washing machine. By situating Needs and Requirements into the FBS framework, it is possible to properly represent all the tasks and the related cognitive processes characterizing the earliest stages of the new product development