Abstract A novel 2R1T (two rotational and one translational degrees-of-freedom) parallel spindle head (PSH) without parasitic motion is proposed which is based on the specific 3-UPU (P and U stand for prismatic joint and universal joint, respectively) parallel mechanism (PM). A modified virtual joint method (VJM) is proposed to solve the deformation analysis of this special PM whose action points of constraint forces are not directly on the solid structure of the mechanism in the gravitational field. Meanwhile, to obtain the relationship between the compliance of the prismatic joint and its length, a Response-Surface-based automation method is proposed with ANSYS workbench software. The workspace of the mechanism is drawn, and the deformation of the mechanism in the gravitational field is obtained within the sub-workspace of full-circle-rotation. The improvement scheme of reducing the deformation of the PSH is proposed.

中文翻译：

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重力场下新型三自由度平行主轴头的变形分析

摘要 基于特定的 3-UPU（P 和 U 分别代表棱柱关节和万向节），提出了一种没有寄生运动的新型 2R1T（两个旋转自由度和一个平移自由度）平行主轴头 (PSH)。并联机构（PM）。针对这种特殊永磁体在重力场下的约束力作用点不直接作用于机构实体结构的变形分析，提出了一种改进的虚拟关节法(VJM)。同时，为了获得棱柱接头的柔度与其长度之间的关系，结合ANSYS工作台软件提出了一种基于响应面的自动化方法。绘制机构的工作空间，并在全圆旋转子工作空间内得到机构在引力场中的变形。