  A new computer haptics algorithm to be used in general interactive
manipulations of deformable virtual objects is presented. In multimodal
interactive simulations, haptic feedback computation often comes from contact
forces. Subsequently, the fidelity of haptic rendering depends significantly on
contact space modeling. Contact and friction laws between deformable models are
often simplified in up to date methods. They do not allow a "realistic"
rendering of the subtleties of contact space physical phenomena (such as slip
and stick effects due to friction or mechanical coupling between contacts). In
this paper, we use Signorini's contact law and Coulomb's friction law as a
computer haptics basis. Real-time performance is made possible thanks to a
linearization of the behavior in the contact space, formulated as the so-called
Delassus operator, and iteratively solved by a Gauss-Seidel type algorithm.
Dynamic deformation uses corotational global formulation to obtain the Delassus
operator in which the mass and stiffness ratio are dissociated from the
simulation time step. This last point is crucial to keep stable haptic
feedback. This global approach has been packaged, implemented, and tested.
Stable and realistic 6D haptic feedback is demonstrated through a clipping task
experiment.
