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ACTA AERONAUTICAET ASTRONAUTICA SINICA ›› 2017, Vol. 38 ›› Issue (9): 421188-421188.doi: 10.7527/S1000-6893.2017.421188

• Material Engineering and Machine Manufacturing • Previous Articles     Next Articles

Mobility analysis of a deployable truss-antenna mechanism- Method based on link-demolishing and equivalent idea

XU Yundou1,2, LIU Wenlan1, CHEN Liangliang1, YAO Jiantao1,2, ZHAO Yongsheng1,2, ZHU Jialong3   

  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 National Education, Yanshan University, Qinhuangdao 066004, China;
    3. China Academy of Space Technology(Xi'an), Xi'an 710100, China
  • Received:2017-02-24 Revised:2017-03-21 Online:2017-09-15 Published:2017-04-19
  • 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 method for Degree Of Freedom (DOF) analysis of spatial mechanisms with multiple coupled-loops is proposed based on the link-demolishing and equivalent idea, in view of the multi-loop coupling characteristic of a deployable truss antenna assembled by tetrahedral elements. The coupling constraint chain of the deployable tetrahedral element is removed, and the remainder is regarded as a parallel mechanism. The number and characteristic of the DOF of each output node are then analyzed using the screw theory, and the equivalent serial kinematic chain between the output nodes and the fixed node are then established. The equivalent mechanism of the deployable tetrahedral element is obtained by reconstructing the coupling constrained chain. The number and characteristic of the DOF of the equivalent mechanism are got using the modified G-K formula and the reciprocal screw theory, respectively. As a result, the kinematic characteristics of the tetrahedral element are known. The structure of the minimum composite unit and the large-scale truss deployable antenna are simplified, according to the equivalent mechanism and the combination of the tetrahedral elements. The numbers of the DOF of the minimum composite unit and the large-scale truss deployable antenna are derived on the basis of the geometric constraint equations. The simulation model for a deployable truss antenna assembled by 27 tetrahedral elements is built, and its DOF is verified. The result shows that the DOF of the antenna analyzed by the proposed method is correct. The method lays a foundation for further analysis of the kinematics and dynamics of similar type of antennas, providing a new idea for DOF analysis of other multi-loop coupling mechanisms.

Key words: link-demolishing and equivalent method, tetrahedron cell, deployable antennas, mobility, screw theory

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