Christian Duriez Frédéric Dubois Abderrahmane Kheddar Claude Andriot Realistic Haptic Rendering of Interacting Deformable Objects in Virtual Environments http://arxiv.org/abs/0804.0561 2008 CoRR abs/0804.0561 db/journals/corr/corr0804.html#abs-0804-0561 informal publication