并联机床不同位形下的运动精度评价指标

以6自由度6TPS型并联机床为模型，推导出机构输入和输出的误差传递方程，分析了单个支链和整个系统的误差传递情况。利用雅可比矩阵的奇异值分解，得到影响位形精度的三个误差敏感性指标，即误差综合敏感度、误差绝对敏感度和误差方向敏感度。定义了综合误差系数和综合误差度，并以此作为评价不同位形运动精度的指标。最后，利用一台实际的并联机床，对不同加工轨迹的运动精度进行了评价，确定最优的加工轨迹。

PRECISION MEASURES FOR VARIOUS CONFIGURATIONS OF PARALLEL KINEMATIC MACHINE TOOLS

Based on the structure of 6-TPS parallel kinematic machine tools, the mapping from machine's kinematics errors to tool's motion errors is formulated, and the relations between input errors and output errors of both single kinematic link and whole machine are analyzed. The singular values of Jacobian matrix are used to define three error sensitivity measures, which are comprehensive error sensitivity, absolute error sensitivity and directional error sensitivity. According to these, two terms are defined, which are named comprehensive error coefficient and comprehensive error degree, and used to evaluate the precision of various configurations of this type of mechanisms. At last, based on a real parallel kinematic machine tool - VAMT1Y, the kinematic precisions under various tool trajectories are compared, and a relatively optimal trajectory is chosen.