基于机器视觉的螺纹参量测量系统

摘要

为了高精度测量螺纹的各项参量，建立了基于机器视觉技术的螺纹参量测量系统。采用螺纹工件旋转、相机跟随拍摄的方式采集螺纹在平行背光下的轮廓数据，实现了螺纹的各项参量测量，扩大了系统的测量范围，并且降低了相机标定误差的影响。推导了坐标系统转换方程，通过标定实现了坐标统一，并推导了螺纹参量计算公式；针对CCD相机光轴和螺纹轴线垂直时螺旋线对螺纹牙投影产生遮挡失真情况建立了数学补偿模型。结果表明，得到的测量不确定度小于2μm，重复性优于4μm。该系统可以完成螺纹的各项参量测量。%In order to measure the parameters for screw thread with high-precision, a measuring system of thread parameters based on machine vision technology was established .Contour datas of thread in the parallel back light was obtained by thread workpiece rotation and camera following-shot, and the measurements of thread parameters were realized .The measurement range of the system was expanded and the effect of camera calibration errors was reduced .Coordinate conversion equation was derived , and the coordinate system was unified by system calibration .Calculation formulas of thread parameters were derived .Considering the distortion of thread teeth on the projection of screw line when the optical axis of CCD camera and thread axis were vertical , a mathematical compensation model was built .The experiment results show that the uncertainty of system measurement was less than 2μm and repeatability was better than 4μm.The system can measure the thread parameters .