空间对称型7R机构运动特性分析及组合应用

提出了一种空间对称型7R机构，可利用此机构组合构造空间可展开机构。通过旋量拓扑图分析了其整体自由度，得到了其运动副轴线方位变化时整体机构自由度数目的变化情况；基于反螺旋理论分析了运动副轴线方位不同的情况下运动输出构件的自由度数目和性质，并针对其瞬时性做了判别，发现其在不同运动副轴线方位布置情况下会出现局部自由度与瞬时自由度；分析了机构在不同驱动情况下的奇异特性，得到了机构在不同的驱动下处于奇异位形时的几何条件；最后选定自由度为1时的空间对称型7R机构组合构造了一类单自由度多棱锥型空间可展开机构，通过设置其运动副轴线方位，可以使其具有较大收拢率，同时当机构完全展开时，奇异特性使得其具有较好的力学性能。通过多个棱锥型空间可展开机构的组合，可以构造出新型大尺度空间可展开机构，在航空航天领域具有较好的应用前景。

Kinematic characteristics analysis and assembly application of a spatial symmetric 7R mechanism

A spatial symmetric 7R mechanism is proposed in this paper, constructing space deployable mechanisms. Firstly, the overall degree of freedom (DOF) is analyzed based on the screw constraint topology diagram, obtaining the variation of DOFs of the whole mechanism when the orientation of the joint axes changes. Then, the number and nature of DOFs of the motion output component in different orientations of the joint axes are analyzed based on the inverse screw theory. and the transient nature of the DOFs are analyzed. It is found that passive DOF and instantaneous DOF occurred in the arrangement of different joint axes orientations. Furthermore, the singular characteristics of the mechanism in different driving conditions are analyzed, obtaining the geometric conditions of the mechanism in the singular configuration under different driving conditions. Finally, a class of single-DOF polygonal pyramid-shaped space deployable mechanism is constructed by combining spatial symmetric 7R mechanisms with DOF at one. By setting the joint axes orientations, the mechanism yields a large folding rate, and due to its singular properties, it has good mechanical properties. Through the combination of a plurality of pyramid-shaped space deployable mechanisms, new large-scale space deployable mechanisms can be constructed, showing good application prospects in the aerospace field.