一种新型三自由度并联机构的运动学分析

Kinematic Analysis of a Novel 3-DOF Parallel Mechanism

提出一种基于3UPS-UP机构的新型三自由度并联机构,该机构的特点是将3UPS-UP并联机构中的P副替换为无框电机,并改变各支链U副的位置使得UPS支链的U副组成一个平面,而UP支链的U副不在此平面内。之后利用有限旋量建立该机构的拓扑模型,基于有限与瞬时旋量间的微分映射规律建立该机构的速度模型。最后提出表征该机构运动/力传递效率的指标——虚功率传递率,分析研究了新型三自由度并联机构的运动学性能。基于有限瞬时旋量理论揭示了并联机构拓扑与运动学模型之间的内在关系,为机构在统一的理论框架下实现拓扑与运动学模型的建立提供了简洁直观的方法。

A novel 3-DOF parallel mechanism based on 3UPS-UP mechanism is proposed.The structure characteristic of the proposed mechanism is that P pairs in 3UPS-UP parallel mechanism are replaced by frame free motors,and the position of U pair in each limb of 3UPS-UP parallel mechanism is changed so that the U pairs of three UPS limbs constitute a plane,while the U pair of UPlimb is not in this plane.Then,topological model of the presented mechanism is established by finite screw theory,and velocity model of the mechanism is established based on the differential mapping relationship between finite screw and instantaneous screw.Finally,the virtual power transmissibility,which is used toevaluate the motion/force transfer performance of the mechanism,is proposed,and kinematic performance of the 3-DOF parallel mechanism is analyzed.In this paper,internal relationship between the topology model and kinematic model of the parallel mechanism is revealed based on finite and instantaneous screw theory,and a concise and intuitive method is provided to establish the topological model and kinematic model of parallel mechanism under a unified theoretical framework.