Martin Frey Jens Hoogen Rainer Burgkart Robert Riener Physical Interaction with a Virtual Knee Joint - The 9 DOF Haptic Display of the Munich Knee Joint Simulator. 570-587 2006 15 Presence 5 http://dx.doi.org/10.1162/pres.15.5.570 db/journals/presence/presence15.html#FreyHBR06