目的 为实现工作臂末端到达平面或曲面内特定位置，提出一种应用于大型构件印刷的2–UCU/U并联驱动双向转动机械臂。方法 应用螺旋理论分析2–UCU/U机构的约束螺旋系，得出该机构的自由度，验证输入选取的合理性。利用封闭矢量法，求解得出机构的位置反解，建立速度雅可比矩阵。使用搜索法，借助Matlab求得机构的工作空间，分析机构输入与输出运动关系。结果 求解得到2–UCU/U并联驱动双向转动机械臂的工作空间，其形状为球形曲面;分析表明，该机构的运动为俯仰和偏航2个方向的转动。结论 驱动副的同向运动实现工作臂的仰俯运动，驱动副的反向运动实现工作臂的偏航运动，因此可使工作臂末端到达工作面所需位置，最终可使连于工作臂末端的工具在特定位置工作。

The work aims to propose a novel 2-UCU/U parallel drive bidirectional rotating mechanical arm applied to large component printing to make the working end of the mechanical arm reach a specific position in a plane or a curved surface. The constrained screw of 2-UCU/U mechanism was analyzed with screw theory. The degree of freedom property of the mechanism was obtained, and the rationality of the input selection was verified. The inverse position solution of the mechanism was obtained with the closed vector method, and the velocity Jacobian matrix was established. The workspace of the mechanism was obtained with search method with the help of Matlab. The motion relationship between input and output of the mechanism was analyzed. The workspace of 2-UCU/U parallel driving bidirectional rotating mechanical arm was solved, and its shape was spherical surface. Analysis showed that the motion of the mechanism was rotation in both pitch and yaw directions. The same direction movements of the driving pairs realize the pitching movement of the working arm, and the reverse direction movements of the driving pairs realize the yawing movement of the working arm. Therefore, the working arm can reach the required position of the working surface, and finally the tool connected to the end of the working arm can work at a specific position.