基于三维激光扫描的倾斜圆面直径测量系统

Development of a diameter measuring system for inclined circular plane based on 3D laser scanning

针对倾斜圆面的空间几何特征,提出将三维激光扫描技术与虚拟环境引导定位结合的快速圆面直径测量系统。该系统通过圆面边缘端点来约束移动激光扫描仪的扫描视角与深度,并在虚拟环境下实时跟随扫描仪轨迹构建虚拟测量基准面,进而参考已标识的端点与基准面相对位移变化,来逐步规划扫描仪的轴向运动路径,以此实现边缘轮廓的自动高质量采样;依据高度特征变化识别定位圆面边缘端点,并结合空间投影和最小二乘原理拟合出圆面直径。为验证系统的精度和可靠性,对处于不同倾斜状态的圆台工件(55±5mm)进行直径检测。结果显示,系统可在3s内完成直径测量,检测分辨率为5μm、检测精度为20μm。实际运行结果表明,该设计系统具有高自动性和高效性,能很好满足在线生产中对倾斜圆面直径的检测要求。

According to the geometric characters of inclined circular plane, a novel rapid diameter measur- ing system integrating three-dimensional （3D） laser scanning technologies and virtual environments is proposed in this paper. In this system,an approach based on the concepts of end points is firstly used to control the view angle and scanning depth of portable laser scanner. Then, the virtual measurement da- tum planes are established by online following the scanning trajectory step-by-step, as well as reference to primary datum. Thus,the relative displacements along three orthogonal directions can be determined between marked end point and virtual measurement datum planes, which directs the scanner to move to the next position. Consequently,high-quality sampling of critical surface area can be automatically per- formed. On the other hand,the positions of end points are identified and located according to their height features. Finally,the diameter of inclined circular plane can be obtained by using space projection theory and least square method. The experiments on different inclining circular planes （55 ±5 mm） were carried out to determine the accuracy and reliability of measuring system, The experimental results indicate that a inclined circular plane with a diameter about 55 mm is perfectly measured in only 3s with the resolution less than 0. 005 mm and the measuring precision over 0. 020 ram. According to the actual operation re sults, this proposed measuring system is has high automation and high efficiency,and can be well accept- able for application as online diameter detection for inclined circular plane in industrial production.