目的 分析含有闭环单元的三自由度2-UPS/(S+SPR)R并联机构是否具有伴随运动，并对该机构的位姿正逆解进行分析。方法 利用欧拉变化得到旋转矩阵，结合机构的结构特性建立约束方程，分析机构是否具有伴随运动和机构的位姿逆解。利用粒子群（PSO）算法分析机构的位姿正解。结果 该机构不具备z轴方向的转动伴随运动，建立了位姿逆解方程；通过PSO算法在输入驱动参数的情况下，可以精确地得到动平台的位姿。结论 机构不存在伴随运动，通过PSO优化算法得到了位姿正解精确的数值解，为分析机构的工作空间提供了良好的基础。

The work aims to analyze whether a three-degree-of-freedom 2-UPS/(S+SPR)R parallel mechanism with closed-loop elements has concomitant motion and its forward and inverse position solutions. The rotation matrix was obtained by Euler's change, and the constraint equation was established based on the structural characteristics of the mechanism to analyze whether the proposed mechanism had concomitant motion and its reverse position solution. The particle swarm optimization (PSO) algorithm was used to analyze the forward position of the mechanism. The mechanism had no concomitant motion of the z-axis rotation, and the inverse position equation was established. The PSO algorithm could accurately obtain the position of the moving platform when the driving parameters were entered. The proposed mechanism does not have concomitant motion. The precise numerical solution of the forward position solution is obtained through the PSO optimization algorithm, which provides a good basis for analyzing the working space of the mechanism.