抄録
In this paper, a new type of 2-DOF spherical wrist mechanism is proposed for minimally invasive robot surgery. It is composed of the spherical 4-bar mechanism whose ground link is connected to the end link of slave robot arm by a revolute joint. Due to the hybrid serial and parallel kinematic structure, for the given desired orientation workspace, it may be designed compactly with enhanced stiffness characteristics compared to fully serial or parallel wrists. For the realization of symmetric orientation workspace, optimal synthesis is performed so that the spherical 4-bar mechanism is designed as a straight line mechanism on a sphere. Then, the 2-DOF spherical wrist is realized by connecting the ground link of the synthesized 4-bar linkage to the end link of slave robot arm using a revolute joint. For the proposed spherical wrist, screw-based Jacobian is derived and instantaneous kinematic relation is also suggested via the theory of screws.
