Hexapod intervention planning for a robotic skull-base surgery system

This paper introduces a novel intervention planning methodology facilitating the use of a parallel manipulator (Hexapod) in a robotic skull-base surgery (.SBS.) system. This safety intensive procedure requires a cavity to be created in the skull-base so as to allow access to deep-seated brain areas that are inaccessible by other routes. An image-guided system (presenting 3-D information) allows the surgeon to pre-operatively define the features that are to be avoided. Although the Hexapod used has good positioning accuracy and high stiffness, its workspace suffers from some undesirable characteristics. A novel technique has been developed to alleviate this problem by means of segregating the task-envelope (i.e. the cavity in the skull-base) and Hexapod workspace generation process. The placement of the task-envelope within the reachable workspace of the Hexapod is planned in a virtual world. This "placement" is then replicated in the physical world by the use of a dexterous base robot supporting the Hexapod. This ensures that the region encapsulated by the task-envelope encapsulated is fully reachable by the Hexapod.