由于传统测量方法及仪器设备无法满足在机实时检测工件三维尺寸的要求,本文基于双目立体视觉视差原理,搭建了一套可在车间现场操作的在机测量工件三维尺寸的视觉系统.首先,介绍了改进的基于平面圆靶标的双目视觉测量系统标定方法.然后,用阈值分割算法从背景中识别出待测工件,采用Canny算子和多边形逼近法提取工件轮廓和轮廓关键特征点,并在极线约束的特征点匹配算法基础上,提出一种基于灰度相关的密集型精匹配算法,获得了工件边缘轮廓关键特征点云的三维坐标数据.最后,对匹配所得特征点云进行数据处理和特征拟合计算,得到了工件的关键尺寸.在车间数控机床上对有斜面及孔结构的工件进行了在机测量实验,结果显示,该系统检测精度达±1.3％以上.%As traditional measuring methods and equipment can not meet the requirement of 3D measurement of workpiece dimensions on-machine in real-time, an on-machine 3D vision measuring system based on the principle of binocular stereo vision was established to work at the workshop. Firstly, A stereo vision system calibration method by using a plane calibration plate was introduced. Then, threshold segmentation algorithm was used for recognizing and extracting the workpiece from the background and the Canny operator and polygonal approximation method were used for extracting the workpiece contour and the contour feature points. Furthermore according to the matching algorithm based on the epipolar constraint, a gray dependent based intensive fine matching algorithm was proposed and the 3D coordinate data of the workpiece contour key feature points were obtained. Finally, the data of matched feature points were processed and fitted, and the key dimensions of workpiece were obtained. On a Computer Numerical Control(CNC) machine in the workshop, an experiment to measure the 3D dimensions of a workpiece with a cant and holes shows that the measurement accuracyrncan reach ±1. 3% or more.
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