Design and analysis of a novel 2 CPR/RRR planar  translational parallel mechanism
                                  CHEN Zihao1，ZHANG Yanbin1, 2 ，JING Xianling1，WANG Keming1，XU Zehua1
(1. School of Mechatronics Engineering, Henan University of Science and Technology, Luoyang 471003,China;2. Henan Provincial Key Laboratory of Robotics and Intelligent System, Luoyang 471023,China)

Abstract: In order to solve the problem of strong motion coupling caused by structural coupling of parallel mechanisms, a novel 2CPR/RRR planar translational parallel mechanism with one pure constrained kinematic chain was proposed. Based on the screw theory, the degree of freedom and output motion characteristics of the mechanism were analyzed. The position vector equations were established in terms of the geometric conditions of the mechanism, and the kinematic mathematical mode were derived under the different input forms, rotary or linear. Kinematic simulation was performed by using Admas and Matlab, the kinematical curves of displacement, speed and acceleration were described. Finally, a new hybrid 3D printer was designed based on the parallel mechanism proposed. The experimental results show that when the rotary displacements of the cylindrical pair is selected as the actuated inputs, the Jacobian matrix is a diagonal one and the mechanism has the uncoupled kinematics. Especially, while the linear displacements of the pair is as the inputs, the Jacobian becomes an unit matrix and it shows fullyisotropic throughout its whole workspace.

Key words: planar parallel mechanism; pure constrained kinematic chain; screw theory; kinematic analysis