A Pilot Protocol Study on How Designers Construct Function Structures in Novel Design

This paper reports a pilot protocol study that examines how designers construct function models as they develop and explore solution architectures for novel design problems. The purpose of this pilot project is to establish the experiment method and analysis protocol so that a repeatable and statistically large pool of participants can be used to draw significant conclusions about function model construction. In the study, voluntary participants with varied levels of experience in product design and function modeling are given a novel design problem and asked to develop functional architectures as part of concept development, using function structures as the modeling tool/language. The modeling actions are videotaped and the designers are interviewed using a predesigned questionnaire after the experiment. The data is analyzed using a predefined protocol that encodes the addition, deletion, and modification of model elements such as functions, flows, and text, and also actions such as reading the problem statement and pausing. The protocol analysis reveals patterns of modeling activities, such as forward chaining (expanding the model by adding functions to the head of flows and flows outgoing of functions), backward chaining (adding functions to the tail of flows and adding flows incoming to functions), and nucleation (starting with a few disconnected functions and flows, and gradually connecting them to complete the model). In aggregate, these observations provide insight into designers’ thinking patterns while exploring solutions to unseen problems using function structures. The protocol is demonstrated to be complete within the scope of the study. The preliminary findings based on the two participants indicate that various parameters of solution exploration may largely vary between designers. The overall approach of model expansion also varies between forward chaining and nucleation. However, at a finer resolution of observing modeling actions, designers generally prefer nucleation or forward chaining of functions and forward or backward chaining of flows.