Modern CAD systems offer many powerful functions to handle parts and assemble them. However, these functions often mask problems that only occur on the final production stage (for example, positioning difficulties for two parts before fixing). The ESKUA project aims to solve this issue by providing a tangible way to test an assembling task, as soon as possible in the design process. In this Tangible User Interface (TUI) based system, each CAD part is associated to a real world object, called interactor. Each action performed with these interactors is captured by a camera, and then visualized in the CAD software. From a usability point of view, it is very important to provide an appropriate interactor family. This paper deals with a design methodology for such a set. First, we show how an object can be characterized in the assembling context, regarding a theoretical definition of assembling task. Then, we detail how our methodology gathers together parts that share the same value for a given assembling criterion, and how it builds interactors from this analysis, as abstractions of each subset properties. Finally, we validate the proposed approach with an experimental use to find out an interactors set for mechanical parts assembling.
In this paper, we present the concepts of the ESKUA (Experimentation of a Kinesics System Usable for Assembly) platform that allows designers to carry out the assembly of mechanical CAD (Computer Aided Design) parts. This platform, based on tangible user interface lead taking into account assembly constraints from the beginning of the design phase and especially during the phase of CAD models manipulation. Our goal is to propose a working environment where the designer is confronted with real assembly constraints which are currently masked by existing CAD software functionalities. Thus, the platform is based on the handling of physical objects, called tangible interactors, which enable having a physical perception of the assembly constraints. In this goal, we have defined a typology of interactors based on concepts proposed in Design For Assembly methods. We present here the results of studies that led to the evolution of this first interactors set. One is concerning an experiment to evaluate the cognitive aspects of the use of interactors. The other is about an analysis of existing mechanical product and fasteners. We will show how these studies lead to the evolution of the interactors based on the functional surfaces use.