A Collision Model for Rigid and Deformable Bodies

| In this paper, we describe models and algorithms designed to produce eecient and physically consistent dynamic simulations. These models and algorithms have been implemented in a unique framework, modeling both deformations and contacts through visco-elastic relations. Since this model of interaction (known as \penalty based") is much debated, we present it in detail. Indeed, the \penalty" based model is said to have two major drawbacks : the diiculty in-determining visco-elastic parameters and in-choosing the computation time step. We present a solution for both problems based on physical concepts. Finally, we will show results comparing real data, \impulse" based simulation and \penalty" based simulation. Contribution of the paper | The contributions of this paper are an in-depth study of the diierent problems raised by the penalty model of collision, an automatic way to identify the parameters of the collision and an algorithm able to control the numerical divergence of this model. These theoretical results have been implemented in a dynamic simulator and we have proven their correctness through experiments comparing real and simulated data for an extreme case : a collision between rigid bodies. The work presented is useful for any application which requires a dynamic simulation that includes deformables bodies, i.e. cables in robotic cell, surgeons training, surgery planning, ... Abstract In this paper, we describe models and algorithms designed to produce eecient and physically consistent dynamic simulations. These models and algorithms have been implemented in a unique framework, modeling both deformations and contacts through visco-elastic relations. Since this model of interaction (known as \penalty based") is much debated, we present it in detail. Indeed, the \penalty" based model is said to have two major drawbacks : the diiculty in-determining visco-elastic parameters and in-choosing the computation time step. We present a solution for both problems based on physical concepts. Finally, we will show results comparing real data, \impulse" based simulation and \penalty" based simulation.