An apparatus for interfacing the movement of a shaft with a computer includes a support, a gimbal mechanism having two degrees of freedom, and three electromechanical transducers. When a shaft is engaged with the gimbal mechanism, it can move with three degrees of freedom in a spherical coordinate space,...http://www.google.co.uk/patents/US20040066369?utm_source=gb-gplus-sharePatent US20040066369 - Physically realistic computer simulation of medical procedures
