欠秩三自由度3-UPU并联角台机构运动特性分析

分析了一种欠秩三自由度3-UPU并联角台机构(支链移动副两端转动副相互平行)的运动特性。首先，用反螺旋理论分析了在初始位置和发生位移后该机构的运动特性。其次，得到了在初始位置和发生位移后该机构的主螺旋。研究表明，该机构在不同的位置下有3个连续的移动自由度，即有相同的自由度数目及相同的自由度的性质．因而该机构是一种性能稳定的、适用的机构。通过研究，丰富了欠秩三自由度并联机构的理论。

Kinematical characteristics analysis of deficient ranked 3DOF 3-UPU parallel-truncated pyramid mechanism

The kinematical characteristics of a kind of deficient ranked 3DOF 3-UPU parallel-truncated pyramid mechanism (the rotation pair at both end of moving pair of branch link are mutually parallel) was being analyzed. Firstly, the kinematical characteristics of this mechanism in its initial position and in the position after a translation happened were analyzed by reciprocal screw theory. Secondly, the main screw of this mechanism in the two positions was obtained. The research indicates that this mechanism has 3 continuous moving DOF under different positions, namely that it possesses identical number of DOF and identical property of DOF. Thus this mechanism is a kind of steady functioned and suitable mechanism. By way of this research, the theory of deficient ranked parallel mechanism with 3DOF is being enriched, and at the same time there is important significance for lots of problems such as the control of robot and path planning etc.