A model for the dynamic simulation of flexible bodies subject to non-penetration constraints is presented. Flexible bodies are described in terms of global deformations of a rest shape. The dynamical behavior of these bodies that most closely matches the behavior of ideal continuum bodies is derived, and subsumes the results of earlier Lagrangian dynamics-based models. The dynamics derived for the flexible-body model allows the unification of previous work on flexible body simulation and previous work on non-penetrating rigid body simulation. The non-penetration constraints for a system of bodies that contact at multiple points are maintained by analytically calculated contact forces. An implementation for first- and second-order polynomially deformable bodies is described. The simulation of second-order or higher deformations currently involves a polyhedral boundary approximation for collision detection purposes.
David Baraff, Andrew P. Witkin