Abstract:Different from the existing methods by using constraint singularity or the chain singularity to synthesis metamorphic parallel mechanisms, an actuated metamorphic parallel spherical joint of full rotation of the one-dimensional, two-dimensional and three-dimensional rotation by way of opening and locking actuated kinematic pair was presented through the method of finite screw. Using the screw theory, the degree freedom of three configurations of the actuated metamorphic parallel spherical joint was analyzed, the mechanism kinematics was studied according to the structure characteristics and geometric constraints of the actuated metamorphic parallel spherical joint. Finally, SmPU actuated metamorphic chain was obtained according to integrating the actuated metamorphic parallel spherical joint (Sm) with P kinematic pair and U kinematic pair serial limb. Based on the SmPU actuated metamorphic chain, 3-SPS/SmPU actuated metamorphic parallel mechanism of six motion modes was presented. The method of the type synthesis actuated metamorphic parallel spherical joint can also be applied to type synthesis other actuated metamorphic parallel joints, the metamorphic method was simple and effective, and constraint singularity and the chain singularity could be avoided effectively in the metamorphic process.