2-PrRS-PR（P）S并联变胞机构自由度分析与仿真

摘 要：針对并联机构输出自由度固定，难以适应变化的环境和工况的问题。根据变胞理论中改变运动副方位特征实现构态变换的原理，设计一种新型可变转动副轴线的2 PrRS PR（P）S并联变胞机构，通过机构的变胞实现机构在不同构态下输出自由度和工作空间的变化。2 PrRS PR（P）S机构包含3个分支、动平台和静平台，利用移动副作为驱动副，其中分支2和分支3能够通过改变移动副的位移来改变的可转轴线转动副在滑槽中的位置，进而改变其转动轴线的方向，且分支1上连杆的移动副在轴线变化时被动作用，实现机构不同构态的变化。根据机构特点，利用螺旋理论对2 PrRS PR（P）S机构2个工作构态进行自由度分析和计算，应用多自由度并联机构输入选取理论确定主动输入副。利用SolidWorks软件建立三维实体模型，并将2种工作构态模型分别导入到ADAMS软件，对其进行自由度的分析和验证。计算和仿真结果表明机构工作构态1具有x轴和y轴方向转动自由度、z轴方向移动自由度;机构在构态3具有x轴和z轴方向转动自由度、y轴方向移动自由度。机构能够根据需求改变工作构态实现输出变化。

关键词：并联机构;变胞机构;自由度分析;螺旋理论

中图分类号：TH 112.1

文献标志码：ADOI：10.13800/j.cnki.xakjdxxb.2019.0124文章编号：1672-9315（2019）01-0168-07

DOF analysis and simulation of 2 PrRS PR（P）S

parallel metamorphic mechanism

MA Kun，MA Hong wei，TIAN Hai bo

（College of Mechanical and Engineering，Xi’an University of Science and Technology，Xi’an 710054，China）Abstract：Since the DOF of parallel mechanism is unchanged and can not adapt to the changing environment and working condition.Based on the theory of metamorphic that changing the orientation of kinematic pairs can lead to configuration transformation，a novel metamorphic parallel mechanism of 2 PrRS PR（P）S mechanism that can change the orientations of the axis of the revolute pair has been designed to change the output and workspace.The mechanism comprises three limbs，moving platform and static platform.The prismatic pair is the drive pair.The revolute pair of limb 2 and limb 3 can change its rotation axis while the prismatic pair on the upper rod in limb 1 can change passively by the change of displacement of prismatic pair.According to the characteristics of the mechanism，the DOF of two configuration has been analyzed using the screw theory.The driving pair has been selected and verified by the theory of selecting input of multi DOF parallel mechanism.Using SolidWorks software，the model of the mechanism has been built and imported into the Adams software to analyze the mechanism’s DOF.The calculation and simulation results show that the mechanism has two rotational freedom along the x and y axis，a translational freedom along the z axis in configuration 1，two rotational freedom along the x and z axis，and a translational freedom along the y axis in configuration 3.This parallel metamorphicmechanism can change its output according to requirements.

Key words：parallel mechanism;metamorphic mechanism;DOF analysis;screw theory

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