采用约束支链法设计了一种新型空间5自由度并联机构，用于实现动平台的三维移动和两维转动．文中首先利用螺旋理论分析了该并联机构的自由度，推导了机构的约束子矩阵和运动子矩阵，在此基础上建立了机构的完整雅克比矩阵; 然后，利用该雅克比矩阵分析了机构发生奇异的条件，并通过选择动平台工作范围或改变结构尺寸，给出了规避并联机构奇异位形的具体方法; 最后，通过数值算例验证了所提奇异位形规避方法的正确性和有效性．

In the investigation,a new type of spatial 5- DOF parallel mechanism is constructed by constraining branched chains,and is used to realize the three translational DOF and two rotational DOF of a moving platform.First,the DOFs of the mechanism are analyzed by means of the screw theory,and the constraint and movement sub- matrices of the mechanism are deduced.On this basis,a complete Jacobin matrix of the mechanism is esta- blished. Then,the singular conditions of the mechanism are analyzed on the basis of the Jacobin matrix,and two methods to avoid the singularity configuration of the mechanism are proposed by choosing the working range of the moving platform or by changing the mechanism dimensions.Finally,the correctness and effectiveness of the pro- posed method is verified by a numerical example.