具有3T、2T1R和2R1T模式的并联机构构型综合
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国家自然科学基金项目(51275404)和陕西省科技重大专项(2009ZDKG-33)


Synthesis of Parallel Mechanism with 3T, 2T1R and 2R1T Motion Modes
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    摘要:

    基于具有2R1T和2T1R运动模式的并联机构,在其动平台上串联平面平行四边形机构后,提出了一种混联变自由度支链,分析了串联变自由度支链和混联变自由度支链的运动模式。采用旋量理论分析了具有串联和混联变自由度支链的机构在运动模式变换过程中的自由度特征,验证了该机构在不同运动模式下驱动副选取的合理性。在机构自由度和机构驱动副选取合理性分析时,选取不同的杆件作为动平台,简化了分析过程。结果表明,该含有混联变自由度支链的并联机构具有3T、2T1R和2R1T运动模式,当该机构在上述3种运动模式的一般位形下,3个驱动副可以实现对机构的控制。机构在从3T运动模式变换为2T1R运动模式时,机构需通过3T1R瞬时自由度位形;机构在从2T1R运动模式变换为2R1T运动模式时,机构需通过2R2T瞬时自由度位形。当该机构在运动模式变换时,处于3T1R或2R2T瞬时自由度时,机构处于约束奇异位形,需增加1个辅助驱动副,以实现机构运动模式的变换。该机构使用较少的驱动副可以实现多种运动模式,运动模式变换时不需对机构进行重新组装,可以快速实现机构重构。

    Abstract:

    A hybrid variable degree of freedom (DoF) branched chain was proposed after that moving platform of the parallel mechanism with 2R1T and 2T1R motion modes was connected with the planar parallelogram mechanism in series. The motion modes of series variable degree of freedom branched chains and hybrid variable degree of freedom branched chains were analyzed. A mechanism with series and hybrid variable DoF branching chains was constructed. The DoF characteristics of the parallel mechanism in the process of motion mode transformation were analyzed by using screw theory, and the rationality of the selection of driving pairs in different motion modes was verified. When calculating the degree of freedom of mechanism and selecting the reasonable driving pair of mechanism, different rods were selected as the moving platform to simplify the analysis process. The results showed that the mechanism with hybrid variable DoF kinematic chain had 3T, 2T1R and 2R1T motion modes. When the mechanism was in the general configuration of the three motion modes mentioned above, three driving pairs can control the mechanism. When the mechanism was transformed from 3T motion mode to 2T1R motion mode, it needed to pass through 3T1R instantaneous DoF configuration. When the mechanism was transformed from 2T1R motion mode to 2R1T motion mode, the mechanism needed to pass through 2R2T instantaneous DoF configuration. When the mechanism was in the transformation configuration which had 3T1R or 2R2T instantaneous DoF, the mechanism was in constrained singularity configuration, and an additional auxiliary driving pair was needed to control the mechanism. The mechanism can realize multiple motion modes by using fewer driving pairs. It did not need to reassemble the mechanism when the motion mode was changed.

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刘伟,刘宏昭.具有3T、2T1R和2R1T模式的并联机构构型综合[J].农业机械学报,2019,50(12):411-419.

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  • 收稿日期:2019-04-25
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  • 在线发布日期: 2019-12-10
  • 出版日期: 2019-12-10