3-PUS-PU柔顺并联机构运动学分析与优化设计

Kinematic Analysis and Optimal Design of 3-PUS-PU Compliant Parallel Mechanism

提出一种具有高精度、高刚度的3-PUS-PU柔顺并联机构,并对该机构进行运动学分析及优化设计。根据柔性铰链结构与机构间几何关系,对3-PUS-PU柔顺并联机构的运动原理进行阐述,并分析了该机构运动特性。采用空间闭环矢量法建立机构的运动学模型,对机构的输入-输出关系和速度特性进行了分析。基于力学理论,通过求解柔性铰链的极限转角,对机构的工作空间进行分析。根据机构的工作要求,提出定位精度指标和紧凑性指标,并进一步分析机构几何尺寸参数对其性能指标的影响。基于提出的性能指标,采用粒子群优化算法对机构的结构尺寸参数进行优化设计。结果表明,相比优化前,优化后的柔顺并联机构的定位精度提高25%,紧凑性提高81%,机构整体运动性能有了较大的提升,为后续样机研制提供了参考依据。

The 3-PUS-PU compliant parallel mechanism with high precision and high stiffness was proposed.Its kinematic analysis and optimization design were carried out.According to the structure of the flexible hinges and the geometric relations of mechanisms,the motion principle of 3-PUS-PU compliant parallel mechanism was described,and the motion characteristics of the mechanism were analyzed.The kinematics model of the mechanism was established by the closed-loop vector method,and the input-output relationship and velocity characteristics of the mechanism were analyzed.Then,the limit angle of flexure hinges was analyzed based on the theory of elasticity.According to constraint conditions and geometric parameters,the workspace of the mechanism was obtained by the numerical search method.According to the work requirements of the mechanism,the performances of positioning accuracy and compact were proposed.Then,the influence of structure parameters of the mechanism on the performances were analyzed.Finally,the particle swarm optimization algorithm was adopted to optimize the size parameters of the mechanism.Compared with the original mechanism,the optimal mechanism was improved by 25%and 81%for positioning accuracy and compactness,respectively.The results showed that the optimal mechanism performance of the kinematics was good.It can provide guidance for the subsequent prototype development.