全场视觉自扫描测量系统

FULL FIELD OF VIEW LASER SCANNING SYSTEM

为了适应对大型工件的快速精确测量,提出一种由CCD摄像机、振镜和激光线投射器组成的全场视觉扫描测量系统,通过振镜的转动改变线结构光光平面角度来实现对摄像机视场内被测物体的自扫描测量。利用平面网格靶标和基于交比不变原理的径向排列约束(RAC)两步方法实现对摄像机的标定,根据振镜的旋转角度以及光平面在靶面上的交线确定光平面的方位,从而根据摄像机模型和CCD二维图像可获得光平面上的三维数据。试验结果证明,这种方法具有较高的测量精度,能较清晰地测量大型工件上的主要特征,同时具有便携性,便于生产现场使用。

To meet the requirement of accurate and convenient 3D measurement for some large parts in reverse engineering, a full field of view scanning system that is mainly composed of a CCD camera, a galvanometer and a laser projector is proposed. The mirror that is rotated by a galvanometer reflects the laser plane, and sweeps the view field of the camera. The camera is calibrated by using a planar target according to the radial alignment constraint（RAC） approach and the principle of cross-ratio invariance. For obtaining the 3D coordinate of a point in a laser plane, the orientation and position of the laser plane are computed according to the angle of the galvanometer and the intersected lines on the target. Hence the three coordinates of a point on the laser plane can be directly obtained from the camera model and the stripe on CCD image. Experiment studies show that the developed system possesses good accuracy. It can identify the fine structure on a large part, also it is portable and convenient for field measurement.