Kinematic Analyses of 5-DOF 3-RCRR Parallel Mechanism

This paper presents the kinematic analyses of a 5-DOF 3-RCRR parallel mechanism. The end-effector of this mechanism can rotate round rotation center and one reference point on it can translate in a plane parallels to the base platform. Since the traditional Kutzbach-Gru¨bler formula is not valid for this mechanism, the modified Kutzbach-Gru¨bler formula and screw theory are used in the mobility analysis. The Duffy’s spherical analytic theory is used in forward/reverse position analyses. In forward/reverse velocity/acceleration analyses, virtual mechanism principle is used to build a virtual parallel mechanism (3-P_vRCRR), which is equivalent to the initial mechanism (3-RCRR) on kinematics if all rates of virtual pairs (P_v) are set to be zero. At the end, some kinematics curves are presented with a numerical example.