具有两个转动一个移动(1T2R)的三自由度并联机构是少自由度并联机构中的一个重要分支。1T2R三自由度并联机构根据两条转轴的几何关系和性质可以分为P*U*、UP，PU和RPR等四类：目前对1T2R并联机构的奇异研究主要集中于P*U*类、UP类，而对PU类和RPR类并联机构的奇异研究极少。对一种RPR类的 2-UPR-RPU并联机构进行奇异性分析。运用螺旋理论对2-UPR-RPU并联机构进行自由度分析，推导该机构的运动学反解方程，进而求出机构的雅可比矩阵。根据雅可比矩阵求出2-UPR-RPU机构的三类运动学奇异位形，分析该机构约束奇异。研究表明，2-UPR-RPU并联机构没有运动学反解奇异、运动学正解奇异和约束奇异，但是有两种混合奇异。

The 3-DOF parallel mechanism (PM) with one translational and two rotational (1T2R) DOFs is an important category of the lower-mobility PM. The 1T2R 3-DOF PM can be classified into four categories based on the geometry between the two axes of rotations, P*U*-equivalent, UP-equivalent, PU-equivalent, RPR-equivalent PM. The singularity analysis mainly focuses on P*U*-equivalent and UP-equivalent PM, while there is few research on the PU-equivalent and PRP-equivalent PM. A singularity investigation of a 2-UPR-RPU PM belonging to the PRP-equivalent PM of 1T2R is presented. The mobility of a 2-UPR-RPU PM is analyzed by using screw theory. Forward and inverse position relations are established. The Jacobian of the 2-UPR-RPU PM is obtained. Based on the analysis of the Jacobian matrix, three kinds of kinematic singularities of the 2-UPR-RPU PM are identified. The constraint singularity of this PM is analyzed. The 2-UPR-RPU PM has no inverse, forward and constraint singularity and has two kind of combined singularities.