Flexible bones for the haptic prototyping of deformable objects

Accurate modelling of the compliance characteristics of solid models is an important rendering task for increasing the realism of virtual environments. The ability to feel the force and moment stress resultants that cause the bending, twisting, shearing and/or fracture of physically-based models is useful for a large number of application areas including medical training, CAD environments, computer animation and games. An important element of compliance rendering is the mechanics engine that solves the equations governing the deformations and stresses in solid models. The development of such engines has to carefully balance the needs for haptic (not just graphical) realism with the needs for real time processing at rates in the range of 500-1000 Hz. In this paper we describe methods and techniques we have developed for such an engine, and demonstrate their characteristics in a number of applications including design of compliant mechanisms, animation and solid modelling.