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ACTA AERONAUTICAET ASTRONAUTICA SINICA ›› 2019, Vol. 40 ›› Issue (4): 422536-422536.doi: 10.7527/S1000-6893.2018.22536

• Material Engineering and Mechanical Manufacturing • Previous Articles     Next Articles

Kinematic characteristics analysis and assembly application of a spatial symmetric 7R mechanism

HAN Bo1, XU Yundou1,2, YAO Jiantao1,2, ZHENG Dong1, ZHANG Shuo1, ZHAO Yongsheng1,2   

  1. 1. Parallel Robot and Mechatronic System Laboratory of Hebei Province, Yanshan University, Qinhuangdao 066004, China;
    2. Key Laboratory of Advanced Forging & Stamping Technology and Science of Ministry of Education, Yanshan University, Qinhuangdao 066004, China
  • Received:2018-07-13 Revised:2018-08-06 Online:2019-04-15 Published:2018-10-10
  • Supported by:
    National Natural Science Foundation of China (51675458); Key Project of Natural Science Foundation of Hebei Province (E2017203335); Youth Top Talent Project of Hebei Province Higher Education (BJ2017060)

Abstract: A spatial symmetric 7R mechanism is proposed in this paper, constructing space deployable mechanisms. Firstly, the overall degree of freedom (DOF) is analyzed based on the screw constraint topology diagram, obtaining the variation of DOFs of the whole mechanism when the orientation of the joint axes changes. Then, the number and nature of DOFs of the motion output component in different orientations of the joint axes are analyzed based on the inverse screw theory. and the transient nature of the DOFs are analyzed. It is found that passive DOF and instantaneous DOF occurred in the arrangement of different joint axes orientations. Furthermore, the singular characteristics of the mechanism in different driving conditions are analyzed, obtaining the geometric conditions of the mechanism in the singular configuration under different driving conditions. Finally, a class of single-DOF polygonal pyramid-shaped space deployable mechanism is constructed by combining spatial symmetric 7R mechanisms with DOF at one. By setting the joint axes orientations, the mechanism yields a large folding rate, and due to its singular properties, it has good mechanical properties. Through the combination of a plurality of pyramid-shaped space deployable mechanisms, new large-scale space deployable mechanisms can be constructed, showing good application prospects in the aerospace field.

Key words: 7R mechanism, deployable mechanism, degree of freedom, singularity, screw theory

CLC Number: