Patent ID: 8303575

Claim:
A tool constraint mechanism comprising a manipulator and a remote center mechanism mounted thereon, the manipulator providing at least one degree of freedom for positioning the remote center mechanism, and the remote center mechanism providing further degrees of freedom for positioning a tool holder, said holder being suitable for holding a tool which is to be constrained in operation with respect to a remote center point, the orientation of the tool holder being adjustable while maintaining the position of the remote center point fixed with respect to the manipulator; wherein the remote center mechanism comprises a first rigid link coupled to the manipulator by a first revolute joint for rotation about a first axis, and a second rigid link coupled to the first rigid link by a second revolute joint for rotation about a second axis, the tool holder being mounted onto or forming part of the second link, with the first and the second axes intersecting at the remote center, the mechanism being characterised in that the first revolute joint is at a first end of the first rigid link, and that the tool holder is at a distal end of the second rigid link.