平面3自由度并联机构奇异位形研究

Research on singularity of planar 3-DOF parallel mechanism

目的由引起机构部分构件运动的几何条件分析不同分支间引起的奇异位形。方法定义了构件之间相对运动的运动螺旋,分析了机构可以实现的运动自由度的个数及形式,以单个分支上的运动螺旋线性相关性判别奇异位形,得到奇异位形的几何意义。对于不同分支引起的奇异位形,假设将所有主动构件固定,由引起机构部分构件运动的几何条件来描述奇异位形的物理特征。结果得到了2类奇异位形在工作空间的分布特征。结论机构所有关节运动螺旋的反螺旋系代表了机构的公共约束,给出了发生各类奇异的判别准则。

Purposes--To analyze the singular between different mechanism branches by the geo metric conditions which lead to the movement of some components of the mechanism. Methods--After defining a kinematic screw of the relative motion between the components and analyzing the number and form of the freedoms of the motion that the mechanism can realize, the geometric meaning of sin- gular configuration is gotten by distinguishing the singular positions with the linear dependence of ki- nematic screw on a single branch. For the singular configuration caused by different branches, the physical characteristics of singularity is described by the geometric conditions of which cause the movement of some components of the mechanism on the basis of the assumption that all active compo- nents are fixed. Results--The distribution characteristics of the above two types of singular configura- tions in workspace are obtained. Conclusions-The inverse screw system of all joints of the mechanism represents the common constraints of the mechanism, and various singular criteria are given.