可重构3-RPR平面并联机构的静刚度研究

Research on Static Stiffness of Reconfigurable 3-RPR Planar Parallel Mechanism

以3-RPR平面并联机构为研究对象,通过设计一种在驱动、被动和锁定3种状态之间相互切换的移动副和转动副锁定装置,实现机构的重构。对重构前、后机构的静刚度特性进行理论建模和软件仿真。通过锁定任意两个运动副的方式,实现机构的拓扑重构。根据动平台的运动状态对锁定方式进行分类,并建立机构的反向运动学模型。对机构的雅克比进行推导,并基于虚功原理,推导静刚度矩阵。最后,对重构前、后的机构进行静力学虚拟实验,对比分析实验数据。结果表明:拓扑重构可以提升平面并联机构的静刚度性能。特别地,动平台做定轴转动时,其静刚度的提升效果尤其明显。这为少自由度可重构并联机构的性能评价和参数优化提供了理论依据。

Taking the 3-RPR planar parallel mechanism as the research object,the mechanism reconfiguration was realized by designing a moving pair and a rotating pair locking device that could switch between driving,passive&locking states.The static stiffness characteristics of the mechanism before and after reconfiguration were theoretically modeled and simulated by software;the topological reconfiguration of the mechanism was realized by locking any two kinematic pairs;the locking modes were classified according to the motion state of the moving platform,and the inverse kinematics model was established.Then,the Jacobian of the mechanism was derived,and the static stiffness matrix was derived based on the principle of virtual power.Finally,the statics virtual experiments of the mechanism before and after reconfiguration were carried out,and the experimental data were compared and analyzed.The results show that topological reconfiguration can improve the static stiffness performance of the planar parallel mechanism.In particular,the static stiffness performance of the moving platform is especially improved when it is rotated with fixed axis.This provides a theoretical basis for the performance evaluation and parameter optimization of the low-degrees-of-freedom reconfigurable parallel mechanism.