Haptic interaction with global deformations

Force feedback coupled with a real-time physically realistic graphic display provides a human operator with an artificial sense of presence in a virtual environment. Furthermore, it allows a human operator to interact with the virtual environment through "touch". We describe a haptic simulation system that allows a human operator to perform real-time interaction with soft 3D objects that go through large global deformations. We model and simulate such a global deformation using geometrically nonlinear finite element methods (FEM). We also introduce an efficient method that computes the force feedback, in real-time, by simulating the collision between the virtual "proxy" and the deformable object. To perceptually satisfy a human operator, haptics requires a much higher update frequency (at least 1000 Hz) than graphics. We update the graphics using full simulation and interpolate the fully simulated states at a higher frequency to render haptics. The interpolation is made possible by intentionally delaying the display (both graphics and haptics) by one full simulation cycle.