一个特殊3自由度并联机构的精度分析及标定

Accuracy Analysis and Calibration of a Special 3-DOF Parallel Mechanism

运动学标定是一种提高机器精度的有效方法。一个改进的误差分析和标定方法得到仿真验证,解决一个用做锻压操作机台虎钳的特殊3自由度并联机器的标定问题。通过建立运动学正解和逆解模型,得到机构的运动空间并对机构进行运动学精度分析,得到机构所有误差源对终端位姿误差的影响因子。结合零部件加工工艺性及精度分析的结果,确定需要标定的误差源,并利用直接微分法得到机构的雅可比矩阵。随机选点建立误差辨识矩阵对机构运动学参数进行标定辨识,Matlab仿真结果显示,经过1次运算得到的运动学参数误差的辨识值与真值之间的偏差小于5%,验证了针对这一特殊3自由度并联机器的精度分析和标定方法的有效性。

Kinematic calibration is an effective way to improve machine accuracy. An improved error analysis and calibration method is verified through simulation, and it solves the kinematics calibration problem of a special 3-DOF parallel mechanism used in a forging manipulator’s bench clamp. Based on its forward and inverse kinematic model, the workspace is obtained, and kinematic accuracy analysis of the mechanism is carried out to obtaine the influences of all error sources of the mechanism on the terminal pose errors. The Jacobian matrix is obtained by using differential method. Simulation result shows that the difference between the identification value and the true value of the kinematic parameter error is less than 5%, which proves the effectiveness of the new accuracy analysis and calibration method for this special parallel mechanism.