Real-time representation of elastic object

Representation of soft and deformable objects in the virtual environment is an important topic for force feedback. To represent such deformable objects, there are two models: the spring-network model, and the FEM elastic model. For the haptic presentation of the sensation of softness, the problem of large deformation is not fatal, because softness is recognized through a relatively small deformation of the object during the interaction. Hence we apply the linear FEM model to represent a soft object. We propose an idea to avoid changing the displacement boundary condition by converting the displacement boundary condition caused by the user's finger into the equivalent force boundary condition. We have implemented and tested the method in a virtual environment with a force feedback device.