• CN: 11-2187/TH
  • ISSN: 0577-6686

Journal of Mechanical Engineering ›› 2026, Vol. 62 ›› Issue (9): 88-103.doi: 10.3901/JME.260409

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Performance Evaluation and Dimensional Synthesis of a 3PRRR Parallel Manipulator

ZHU Gaoyong1,2, LU Yebo1, ZHANG Lingling2, YE Wei3, YANG Chao1,4   

  1. 1. College of Mechanical Engineering, Jiaxing University, Jiaxing 314001;
    2. Zhejiang Ribon Intelligent Equipment Co., Ltd., Jiaxing 314001;
    3. School of Mechanical Engineering, Zhejiang Sci-Tech University, Hangzhou 310018;
    4. G60 STl Valley Industry & Innovation Institute, Jiaxing University, Jiaxing 314001
  • Received:2025-08-12 Revised:2025-11-11 Published:2026-07-08

Abstract: To solve the dynamics and stiffness modeling difficulties caused by the multi-closed loop and multi-constraint characteristics of parallel mechanisms (PMs), an integrated method of elastodynamic and stiffness modeling for PMs that is applicable to both the pre-design and the prototype design stages is proposed. The model first establishes the element stiffness and mass matrices of each free body based on the matrix structure analysis method, and then extracts the global independent generalized displacement coordinates of the mechanism in the global coordinate system by combining multi-point constraint theory and kinematic constraint equations. The elastodynamic equation of the mechanism is established through Lagrange equation, and the elastostatic stiffness model corresponding to the exit node is established through static condensation technology. Based on the Lagrange equation and overall stiffness matrix, an ellipsoid index for the extreme stiffness and isotropy of the mechanism is established. A multi-objective genetic algorithm is used to establish the Pareto front of the multi-objective optimization problem. Further, the cooperative equilibrium point method is combined to determine a set of optimal solutions on the Pareto front. On this basis, the prototype of the 3PRRR PM is designed. The stiffness and mass matrices of components involving irregular cross-sections are extracted using finite element software to replace those of beam elements in the pre-design stage to achieve rapid performance evaluation of the three-dimensional model of the 3PRRR PM. The maximum error between the proposed theoretical model and the finite element model is within 1.48%. The performance comparison of the mechanism before and after optimization shows that the fundamental frequency, isotropic of the linear stiffness and angular stiffness have been improved by 2.3%, 19.05%, and 43.75%, respectively. The reasonable cross-section design of the links based on the screw theory further improves the performance indices of the mechanism, verifying the correctness and effectiveness of the model proposed in this work.

Key words: parallel manipulator, elastodynamic, stiffness modeling, performance evaluation, dimensional synthesis

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