Model Generation and Modification for Dynamic Systems from Geometric Data

We are experimenting with a prototype implementation of a simulation system for rigid body motion where the objects to be simulated are specified by a geometric description and a few symbolic data, such as object density, the type of hinge between certain bodies, and environmental factors. In our approach, the system automatically generates the appropriate mathematical model describing the current system dynamics, and revises the model so as to account for unanticipated changes in the system’s topology. For example, when simulating impact behavior, the system will not know in advance what objects might collide at which points, thus invalidating the usual approach of defining constraint forces between point pairs that are negligible except when the points are in close proximity. We describe the overall organization of the system, and give a general method to effect this self-modification. Focusing on characteristic cases such as gaining or losing contact and low-velocity collision, we discuss our experience with the system, its flexibilities, and its limitations.