基于显微视觉的UVW直驱平台运动学标定

Kinematic Calibration of UVW Direct Drive Platform Through Microscopic Vision

面向高端制造装备对多自由度纠偏对位系统的快速精密对位要求,设计一种UVW直驱运动平台,提出一种基于显微视觉测量的运动学标定方法,实现平台结构参数误差与垂直度误差的标定与补偿。推导平台基坐标系与末端坐标系间的映射关系,采用图解法分析移动副垂直度误差引起的平台末端位移耦合,建立正逆运动学解析解,在此基础上引入工具坐标系偏差建立误差传递模型;面向平台末端位姿测量,构建一种基于绝对编码图案的显微视觉测量系统,通过对齐测量坐标系与平台基坐标系,获取不同位姿下的平台坐标;搭建UVW运动平台及其视觉测量系统,开展所提方法的运动学标定实验。实验结果表明,平台标定后的X、Y、C轴RMSE由原来的0.2177 mm、0.2298 mm、0.0057°下降到0.0043 mm、0.0083 mm、0.0019°,相比常规方法进一步降低93.97%、19.41%、56.81%,验证了标定方法的有效性,也为UVW平台的精密纠偏定位奠定了基础。

Aiming at the fast and precise alignment requirements of multi-degree of freedom correction alignment system for high-end manufacturing equipment,a UVW direct drive motion platform is designed,and a kinematic calibration method based on microscopic vision measurement is proposed to realize the calibration and compensation of platform structural parameter errors and verticality errors.In this paper,the mapping relationship between the platform base coordinate system and the end coordinate system is derived,the end displacement coupling caused by the vertical error of the moving pair is analyzed by graphical method,and the forward and inverse kinematics are established.A microscopic vision measurement system based on absolute coding pattern is constructed for the orientation measurement of the end of the platform.The platform coordinates under different orientation are obtained by aligning the measurement coordinate system with the platform base coordinate system.The UVW motion platform and its vision measurement system were built,and the kinematic calibration experiments of the proposed method were carried out.The experimental results show that the RMSE of X,Y and C axes after platform calibration decreases from 0.2177 mm,0.2298 mm and 0.0057°to 0.0043 mm,0.0083 mm and 0.0019°,which is further reduced by 93.97%,19.41%and 56.81%compared with the conventional method.The validity of the calibration method in this paper is verified,and it also lays a foundation for the precision correction and positioning of UVW platform.