一种大尺寸视觉测量系统标定方法

Calibration Method for Large-Size Vision Measurement System

针对相距较远的基坐标系与视觉传感器坐标系的标定问题,提出一种高精度标定方法,通过激光跟踪仪建立中间坐标系,基于最小二乘点集配准误差标定激光跟踪仪坐标系与视觉传感器坐标系的关系,采用最小二乘平均刚体变换矩阵标定激光跟踪仪坐标系与基坐标系之间的关系,最后通过坐标变换建立测量基坐标系与视觉传感器坐标系之间的坐标关系,实现大尺寸工件空间相位角度的精确测量.仿真结果证明了最小二乘点集配准方法求解坐标系关系的有效性,同时验证了最小二乘点集配准方法的配准误差与配准点集大小、传感器精度、传感器的位姿关系有关.试验结果表明,该标定方法能够准确可靠地测量大尺寸工件空间角度,测量标准差达到0.007 5°,完全满足工艺要求.

Aiming at the calibration problem of distance between base coordinate system and the vision sensor coordinate system,a high-precision calibration method was proposed.Firstly,an intermediate coordinate system was established with a laser tracker.And then,the least squares point set registration error was used to calibrate the relationship between the coordinate system of the laser tracker and the coordinate system of the vision sensor.The least square average rigid body transformation matrix was used to calibrate the relationship between the laser tracker coordinate system and the base coordinate system.Finally,the coordinate relationship between the measurement base coordinate system and the vision sensor coordinate system was established by coordinate transformation to carry out the measurement of spatial phase angle accurately for large size workpieces.Simulation results show the effectiveness of the least squares point set registration method in solving coordinate system relations,and validate the registration error of least squares point set registration method is related to the size of registration point set,sensor accuracy and sensor pose relationship.Test results show that the calibration method can accurately and reliably measure the spatial angle of large-sized workpieces,and the measurement standard deviation can reach up to 0.0075°,fully meeting the process requirement.