Patent ID: 8245595

Claim:
A robotic system having a two-axis robotic wrist, said system comprising: a reference member having a longitudinal axis, a movable member rotatably movable relative to the reference member, in an undeflected position of the movable member relative to the reference member said wrist having a pitch axis transverse to the longitudinal axis of the reference member for pitch rotation of the movable member relative thereto, a yaw axis perpendicular to the pitch axis and to the longitudinal axis of the reference member for yaw rotation of the movable member relative to the reference member, and a roll axis coaxial with the longitudinal axis of the reference member; a first serial chain linkage connecting the movable member to the reference member, said first serial chain linkage comprising a revolute-universal (RU) linkage having a revolute joint pivotally connecting the RU linkage to the reference member and a universal joint pivotally connecting the movable member to the RU linkage, in the undeflected position of the movable member said revolute joint having a rotation axis and being oriented such that the rotation axis is coaxial with the pitch axis of the wrist, and a second serial chain linkage connecting the movable member to the reference member in a parallel relationship with the first serial chain linkage, said second serial chain linkage comprising a revolute-spherical-revolute (RSR) linkage, said RU linkage being configured together with the RSR linkage such that the movable member is constrained to spherical movement about a center (C) defined by the intersection of the pitch axis, the yaw axis and the roll axis of the wrist, said parallel relationship of the first and second serial chain linkages of the robotic wrist being singularity free and being non-overconstrained.