Abstract—A novel 1T2R with three degrees of freedom redundantly actuated and overconstrained 2RPU-2SPR parallel manipulator is here presented as an alternative approach for high speed machining in aerospace field. Firstly, the actuation and constraints of the parallel manipulator imposed by passive joints are analyzed in terms of the screw theory, and the degree of freedom of the parallel manipulator is further derived. Secondly, the kinematic analysis is carried out, the inverse position and geometric constraint equations of the parallel manipulator are established, and the overall Jacobian matrix was explicitly derived. Subsequently, the stiffness matrix of the chain is deduced considering the elastic deformation of the link, and the stiffness matrix of the parallel manipulator is established by the differential mapping relationship between the actuated chains and the moving platform. The linear and angular stiffness, eigenscrew decomposition, and maximum and minimum stiffness eigenvalues are introduced to evaluate the stiffness characteristics of the manipulator. Finally, through some numerical examples, distributions law of the performance indices of redundantly actuated and overconstrained 2-RPU-2SPR parallel manipulator are illustrated in details. The results demonstrate that the three degree of freedom redundant actuation parallel manipulator proposed in this paper has much better stiffness performance than the 2-RPU-SPR parallel manipulator, and has much more extensive prospect in engineering applications.
Index Terms—Redundantly actuated, overconstrained, parallel manipulator, eigenscrew, stiffness.
Haiqiang Zhang is with School of Mechanical, Electronic and Control Engineering, Beijing Jiaotong University, Beijing, P.R. China (e-mail: 16116358@bjtu.edu.cn).
Hairong Fang is with Beijing Jiaotong University and Robotics Research Center Leader, P.R. China (e-mail: hrfang@bjtu.edu.cn).
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Cite: Haiqiang Zhang and Hairong Fang, "Stiffness Characteristics Analysis of a Novel 3- DOF Parallel Kinematic Machine Tool," International Journal of Engineering and Technology vol. 10, no. 4, pp. 346-354, 2018.
