Interpretability Analysis of Function Structures at Various Levels of Abstraction: A User Study

Function models are used during the conceptual design phase of the design process to model the intended use or objective of a product, independent of the products physical form. Function models also aid in guiding design activities such as generating concepts and allocating design team resources. Recent research efforts have focused on the formalization of functional models through a controlled vocabulary and archival of functional representations in computer-based repositories. However, the usefulness and interpretability of these function models has not been rigorously evaluated. This thesis presents the results of two controlled user studies to ascertain the interpretability of functional representations at four levels of abstraction. These function models vary in abstraction in two dimensions: (1) the number of functions within the model and (2) the specificity of the terms used within the model. As a result of the two user studies, thirty four mechanical engineering graduating students were asked to identify consumer products based on their function model at various levels of abstraction. In addition to identifying the product, participants recorded time and any keywords/aspects in the functional model that aided them in their decision making. Analysis of the results indicates that interpretability of a function model increases substantially by using free language terms over a limited functional vocabulary. The results also indicate that interpretability increases by incorporating human interaction and environmental context of the product within the functional model. Lastly, the number of functions within the functional model correlates with the identification of similar products