The importance of participatory design (PD) is progressively increasing thanks to its capacity to explore a wide variety of concepts, thus increasing the opportunity to create a successful product. In fact the design process should not be a solo activity, as designers often need inputs and other points of view, especially from end-users.
According to the ultimate idea of PD, end-users are actively involved in the various activities of the product development to ensure that their needs and desires are satisfied.
This paper presents a novel approach to the participatory design of product interfaces in a user-centered design (UCD) process. The approach is based on an interactive tool that allows end-users to design custom user interfaces of household appliances taking advantage of their own needs and experiences.
The tool incorporates the analytical and more abstract knowledge of the designers codified in the form of aesthetical, technological and manufacturing constraints (i.e., limitations in the number and geometry of interface components, a limited number of colors, a discretization of the area where interface widgets are placed). This solution allows the end-users to directly design their favorite interface without the interference of any other subject. Through an accurate analysis of the choices done by the users, the designers are able to access to the deepest level of the users’ expression in order to catch their latent needs and tacit knowledge.
The tool has been designed in order to make possible to immediately perform usability tests on the designed interface by using a Mixed Reality prototype.
The paper describes the development of the tool and proposes a methodology that has been specifically addressed to include this tool in a design process based on UCD principles. Both the tool and the methodology are presented through the description of a case-study related to the redesign of a washing machine dashboard. Experimental results show that the proposed tool can be an effective support to design product interfaces during PD sessions.