A GENERIC ALGORITHM FOR THE GENERATION OF PHYSICAL MOVEMENTS OF SOLID SYSTEMS

This paper presents an engine for dynamic animation of solid systems based upon Lagrangian equations. The goal is to animate in an automatic way any scene composed with rigid objects defined in hierarchical structures. Animation control is provided by the description of the various degrees of freedom linking the objects, the inertial elements of these solids, the forces applied to bodies, as well as the supplementary constraints imposed upon objects. The advantages of using object oriented programming and particularly polymorphism to implement these items are briefly discussed. The physical theoretical background is based on an explained derivation of the Partial Differential Equations System formed by Lagrangian equations into an Ordinary second order Differential Equations System. The practical part then consists mainly in a generic algorithm which can automatically build this accurate ODE system from the minimal decription of any scene. Dealing with its resolution some examples are shown in order to compare the merits of some classical numerical methods and to discuss numerical stability problems.