OPTIMIZATION DESIGN AND PERFORMANCE COMPARISON OF TWO 5-DOF PARALLEL MANIPULATORS USED FOR LOADING DEVICE

Bin Zhu,∗,∗∗ Liping Wang,∗,∗∗ Jun Wu,∗,∗∗ and Qi Li∗∗∗

Keywords

Loading device, parallel manipulator, payload uniformity, stiffness, workspace ∗ State Key Laboratory of Tribology and Institute of Manu- facturing Engineering, Department of Mechanical Engineering, Tsinghua University, Beijing 100084, China ∗∗ Beijing Key Lab of Precision/Ultra-precision Manufactur- ing Equipment and Control, Beijing 100084, China; e-mail: zhub18@mails.tsinghua.edu.cn, {lpwang, jhwu}@mail.tsinghua. edu.cn ∗∗∗ Tianjin Key Laboratory of Aerospace Intelligent Equipment Te

Abstract

The reliability study of machine tools draws more and more attention both in academia and industry, and the loading device is very impor- tant for the reliability test as it can provide force and torque to simu- late the cutting force. This paper proposes two 5-degrees of freedom parallel manipulators for developing loading devices, one with 3UPS– 2UPU chains and the other with 4UPS–UPU chains. Workspace, payload uniformity and stiffness performance indices are defined for the two parallel manipulators, and the corresponding performance atlases are represented graphically in the design space. Based on the performance atlases, the geometrical parameters without dimension are determined. The optimum dimensional parameters are achieved based on the non-dimensional parameters. The workspace, payload uniformity and stiffness of the two parallel manipulators with op- timum geometric parameters are compared. The results show that the 3UPS–2UPU parallel manipulator has better payload unifor- mity and higher stiffness than the 4UPS–UPU parallel manipulator. Thus, the 3UPS–2UPU parallel manipulator is used to develop a loading device for 5-axis machine tools. This paper is not only im- portant for designers to develop the loading device but also helpful for researchers to find a better parallel manipulator for the loading device.

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