摘要
针对正四面体的几何结构特点及对称性,将其棱边和顶点分别用两种构件替代,并通过单自由度转动副连接组合得到正四面体的等效几何基础模型。采用添加支链改变约束系的方法得到了基本可动单元体,进一步通过单元体的组合重构,设计了一种类正四面体耦合机构。基于独立运动分流标记法对其进行了运动性质分析,并通过Matlab软件得到各对称节点位移变化曲线,分析表明了设计的新机构具有2个移动自由度并且可以实现向心运动。
A novel coupled mechanism was synthesized based on the particular geometrical construction and high symmetry of the regular tetrahedron. Firstly,two simple types of substitutive element component were designed and implanted in the location of all vertexes and edges contained in the regular solid respectively. An equivalent geometrical basic model was obtained with combination of the element parts connected by revolution joints according to frame of regular tetrahedron. The relative studies of the basic geometrical model with four congruent sub-structures were converted into a 6-bar closed-loop linkage.Secondly,the mobility of geometrical basic model was determined on the basis of independent motion shunting measurement method. The approach of adding chains was adopted to allocate the constraint sets and rearrange the components spatially when the closed-loop linkage was rigid on the basis of the screw theory. The element unit loop structure was abstracted by the means of modifying the constraint set of the6-bar closed-loop linkage with the corresponding added chains symmetrically. Finally,the novel quasiregular tetrahedron coupled mechanism was established with regroup of the identical elementary units according to the same way of combining the equivalent geometrical model. To define the motion of the new mechanism,a three-dimensional model was developed based on the Solid Works for simulation analysis and the displacement variation of the output part and the other two symmetrical node components was provided by Matlab. The results showed that the new-designed coupled mechanism had two translational degrees of freedom which belonged to a plane perpendicular to the base and the three node components located in the vertexes had the same radial motion trend directed to the geometrical centre of the new structure. The mobility and the centripetal characteristic of the mechanism were verified correctively. This new structure can be applied to the executing structure of the deployable mobile robot.
出处
《农业机械学报》
EI
CAS
CSCD
北大核心
2016年第6期373-380,356,共9页
Transactions of the Chinese Society for Agricultural Machinery
基金
国家自然科学基金项目(51475015)
公路养护装备国家工程实验室(长安大学)开放基金项目(310825151130)
关键词
耦合机构
正四面体
添加支链
向心运动
coupled mechanism
regular tetrahedron
adding chains
radial mechanism
