Kinematic analysis and performance evaluation of the 3-PUU parallel module of a 3D printing manipulator

Recently, 3D printing manipulators have attracted extensive attention since they have become promising tools to perform the practical prototyping and distributed manufacturing tasks. To improve the kinematic accuracy, dexterity and efficiency of 3D printing manipulators, the concept of a 6-DOF hybrid manipulator, consisting of a 3-DOF parallel manipulator and a 3-DOF rotational wrist, is proposed in this paper. According to the requirement of 3D printing movements, a three-prismatic-universal-universal (3-PUU) translational parallel manipulator (TPM) is designed. Several kinematic properties of the 3-PUU TPM under study are investigated, including the inverse and forward kinematic problems, workspace determination, and dexterity. Both the inverse kinematics and forward kinematics solutions are derived in closed form, and Jacobian matrix is derived analytically. Moreover, in view of the physical constraints imposed by mechanical joints, the reachable workspace is determined. Finally, the dexterity characteristic of the 3-PUU TPM is evaluated based on the condition number of its Jacobian matrix.