Traitement générique des interactions haptiques pour l'assemblage d'objets issus de CAO. (Generic processing of haptic interactions for the assembly of objects issued from CAD)

In this thesis, we are interested in the treatment of interactions between 3Dobjects in the specific context of haptic assemblies. The aim of the thesis isto study the different dynamic modes that are applicable to the simulation ofCAD assemblies. This field of research involves several scientific and technologicissues on the coupling of haptic interfaces with dynamic simulation engines. Theinteractive-time constraint forces dynamic engine to detect collisions and computethe contact forces very quickly, following a stability criterion. In this context, we propose to apply the technology of haptic interaction tomanage mechanical assemblies of CAD objects. Among the many factors thatinfluence the degree of realism of an interactive simulation of assembly, we focuson the realism of the behaviour of physical objects and on the performance ofusers achieving assembly tasks. In the context of haptic simulations, we proposeto address these two factors simultaneously. Within a single assembly simulation,the user will feel realistic dynamic behaviour during elementary interactions withthe virtual environment, while performing A/D tasks in an efficient way. In the simulations of assembly, we identified two handling phases where thecontact dynamics can be performed : either in a constrained way to help users toposition objects in space, or in a non-constrained way to return realistic haptic in-teractions. The approach is to separate the interactions related to the explorationscenes, from the interactions related to assemblies. Within a single simulation,we propose to use unconstrained dynamic models to process exploratory phaseand the use of constrained dynamic models to process haptic assembly. In a firstcontribution, we propose to use a rigorous modelling of mechanics to simulaterealistic behaviours of objects : we use the methods of non-smooth dynamics andespecially the non-smooth contact dynamics (NSCD) approaches. In a secondcontribution, we propose to identify the different stages that compose the inter-active assembly to assist the user. This assistance consists in a virtual guidancecomposed of geometrical and kinematical constraints applied to the control of the objects to assemble. We present a new method of guidance, called virtualconstraint guidance that applies kinematical constraints that depend on the as-sembly tasks. The transition between the exploratory mode and the assemblymode is made by a geometric guidance inspired by virtual fixtures.