[PP]S类并联机构可实现1移动自由度和2转动自由度，具有广泛的应用前景。2-PRS-PRRU并联机构属于[PP]S类并联机构。运用螺旋理论分析2-PRS-PRRU并联机构的自由度特性，确定动平台的两条连续转轴。研究2-PRS-PRRU并联机构的伴随运动，证明该机构无伴随运动。建立该机构位置正/逆解模型，推导出位置正/逆解的解析表达式，进而求得该机构的雅可比矩阵。通过对雅可比矩阵的分析，确定机构的逆解奇异、正解奇异和混合奇异。2-PRS-PRRU并联机构具有确定的连续转轴和无伴随运动的特性，使其在实际应用中具有很大潜力。

The family of [PP]S parallel mechanism can undergo one translational degree of freedom (DOF) and two rotational DOFs, thus having great potential in practical application. The 2-PRS-PRRU parallel mechanism belongs to the family of [PP]S parallel mechanism. Mobility property of the 2-PRS-PRRU parallel mechanism is analyzed by using screw theory and the two finite rotational axes are identified. Parasitic motion of the 2-PRS-PRRU parallel mechanism is studied. It is proved that this parallel mechanism has no parasitic motion. The forward and inverse position kinematics models are established and the analytical solution is obtained. Jacobian matrix of the 2-PRS-PRRU parallel mechanism is obtained. Inverse, forward and combined singularities are identified based on the analysis of the Jacobian matrix. The 2-PRS-PRRU parallel mechanism has great potentials in practical application because of its identified finite rotational axes and zero parasitic motion.