• CN: 11-2187/TH
  • ISSN: 0577-6686

Journal of Mechanical Engineering ›› 2024, Vol. 60 ›› Issue (19): 40-52.doi: 10.3901/JME.2024.19.040

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New Method and Formula for Degree-of-freedom Calculation of Parallel Mechanism Based on Optimal Paths

SHEN Huiping, LI Ju, ZHU Xiaorong, LI Tao, MENG Qingmei, ZHU Wei, YE Pengda   

  1. Research Center for Advanced Mechanisms Theory, Changzhou University, Changzhou 213164
  • Received:2023-10-05 Revised:2024-04-12 Online:2024-10-05 Published:2024-11-27

Abstract: The non-instantaneous degree-of-freedom (DOF) calculation formula (Yang-Sun formula) for the general over-constraint and non-constraint parallel mechanisms (PMs) is derived for the typical PMs composed of simple branch chain in parallel form, and the optimal path is not taken into account during the DOF calculation.Therefore, when the formula is used to DOF calculation for complex PMs that contain two or more hybrid chain (including generalized hybrid loop PMs), the “calculation paths” are long, calculation process of the independent displacement equation number of loop are complex, the influence of the DOF of each loop on the previous sub-PMs is also cannot be clearly shown.To this end, a new method and DOF formula of PM based on the optimal path is proposed.This presented method is simple, less calculation, and can clearly show the specific influence of the DOF of each loop on the whole DOF of PM, which is especially suitable for the calculation of non-instantaneous DOF of general over-constraint and non-constraint PMs with two or more hybrid branch chains.

Key words: degrees of freedom, parallel mechanism, hybrid branch chain

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