Abstract: To improve the kinematic accuracy of a 6-PSS parallel mechanism, its error analysis and calibration were researched. The error model of 6-DOF parallel mechanism was established by vector method, and the sensitivity of structure parameters to the pose error of the moving platform was obtained by MATLAB tool. Through comprehensive analysis for mechanism's error, on the basis of this mechanism, a new kinematic calibration method based on pose constraints of mechanism coordinate-axis was proposed combining with the forward and inverse of kinematics. According to initial measurement value, the calibration values of mechanism were obtained by using calibration algorithm. The displacement and angle error before calibration and after calibration were obtained with external measuring equipment, and the displacement error was improved from 10 mm to 1 mm and angular error was improved from 0.3°to 0.1°after calibration. The experimental results showed that the proposed calibration method was valid and effective, and could improve the kinematic accuracy of parallel mechanism.

Key words: parallel mechanism, error models, orientation constraint

摘要： 为提高6-PSS并联机构的运动精度，需对其进行误差分析和标定研究。利用矢量法构建并联6自由度机构的误差模型，根据MATLAB计算得到机构的误差源对动平台末端位姿影响的灵敏度。对机构进行误差综合分析，结合运动学正解和逆解，提出一种新的基于机构坐标轴姿态约束的运动学标定方法。根据测量初始值，利用标定算法解算得到机构的标定值。借助外部检测设备测量得机构标定前和标定后的位移和角度误差，标定后位移误差由10mm减小到1mm，角度误差由0.3°减小到0.1°。以实际测量数据验证了该标定方法的有效性和正确性，并最终提高了并联机构的运动精度。

关键词: 并联机构, 误差模型, 姿态约束, 运动学标定