为了对机械加工部件进行高精度、大尺寸、三维立体空间的现场实时测量, 建立了光笔式单目视觉测量系统。对该系统中的新型光笔工艺、算法转换模型、摄像机焦距的优化、光笔笔尖位置的标定进行了研究。首先提出了一种利用光刻工艺设计制作的新型光笔, 其次, 基于近景摄影测量学中的单像空间后方交会原理, 建立了一种新的光笔坐标系与摄像机坐标系之间的转换模型, 通过最小二乘平差法循环迭代求解最优的单像空间外方位元素, 从而确定了转换模型基本参数。最后, 分析了摄像机焦距对光笔式单目视觉测量系统结果的影响, 并提出了一种确定相对准确焦距和光笔测头在光笔坐标系下的位置的方法。实验结果表明: 摄像机坐标系下x轴、y轴、z轴方向的稳定性误差分别为0.042、0.048、0.066 mm; 测量最大误差为0.173 mm,较大程度上满足了光笔式单目测量系统稳定性强和精度高的要求。

In order to achieve the high-precision, large-size, three-dimensional space and real-time measurement of mechanical components, a monocular vision measurement system with a light pen was established. The new technology, algorithm converting model, the optimization of camera focal length and the position calibration of the light pen probe were studied. First, a new type of light pen which was designed by using the photolithography process was proposed. Then, based on resection principle of single image space in the close- range photogrammetry, the new conversion relationship between the light pen coordinate system and the camera coordinate system was established. Optimal exterior orientation elements of single image space was solved by least squares adjustment method in the loop iteration, and basic parameters of the transformation model were determined. Finally, the impacts of focal length on the result of monocular vision measurement system were analyzed, and a method to determine the relatively accurate focus length and the position of light pen probe in the coordinate system of the light pen was proposed. Experimental results indicate that the stability errors in the x-axis, y-axis, z-axis directions of the camera coordinate system are 0.042 733 mm, 0.048 513 mm and 0.066 39 mm, respectively, and the maximum measuring error is 0.173 mm. These results meet the requirements of monocular vision measurement system with a light pen for stability and high accuracy.