空间少自由度并联机构瞬时螺旋运动轴线曲面的几何表示方法

对于单自由度的平面机构或单自由度空间机构来说,机构中各个点的运动都是确定的。机构在运动过程中的一系列瞬时螺旋运动轴线所形成的曲面也是唯一的,比较容易求解,可以得到其数学表达式。但对于多自由度的空间机构来说,由于在每一个位形下,机构的运动有多种可能性,瞬时运动轴线所形成的曲面也不是唯一的,很难得到其数学表达式。本文通过求解空间机构在运动过程中的一系列瞬时运动轴线,利用几何方法绘制出空间少自由度并联机构的瞬轴曲面,从而可以更直观地了解少自由度并联机构的空间运动。

Geometric expression of axodes of spatial lower mobility parallel mechanism

The motion of all points in a planar or a spatial mechanism with only one mobility is determinated,and the axodes formed by all the instantaneous screw axes are also unique and can be solved easily,even the mathematical expression of the axodes can be obtained.However,for a spatial lower mobility parallel mechanism,the mathematical expression of its axode is difficulty to obtain because the motion and the axode have a couple of possibilities for the motion under every configuration.In this paper,a series of instantaneous screw axes of the spatial parallel mechanism during a given spatial motion are solved and applied to draw the axode in 3D space using the geometric method.The motion properties of the lower mobility parallel mechanism can be shown directly by axodes.