用于自由曲面内区域缝隙尺寸的快速检测系统

A Rapid Dimensional Measuring System for Ranged Gapson Freeform Shape

针对自由曲面内区域缝隙的三维几何特征,建立了将三维激光扫描技术与虚拟环境引导定位结合的缝隙尺寸快速测量系统。该系统基于已获取的缝隙截面的关键特征点来约束线激光传感器的扫描视角和扫描深度,逐步调整实现区域缝隙轮廓的自动采样获取;依据绝对差分值的相对变化量来识别定位关键特征点,并在全局坐标系下以非线性最小二乘法对其进行拟合处理,实现区域缝隙的形状描述和几何尺寸表达。为验证系统的精度和可靠性,对具有自由曲线-多尺度尺寸特征的缝隙标准件(200 mm×50 mm×32 mm)进行检测,结果显示:系统可在60 s内完成该区域缝隙的缝宽、缝深、面差检测,检测分辨力为5 μm、检测精度为25 μm;实际运行结果表明:该系统具有高自动性和高效性,能较好地满足在线生产中对自由曲面产品内缝隙尺寸的检测要求。

According to 3D geometric characters of ranged gaps on freeform shape, a novel rapid dimensional measuring system integrating laser scanning technologies and virtual measuring environments was developed. Based on the geometric information of acquired feature points of measured gap, the view angle and scanning depth of laser scanner can be determined step by step, thus automated generating an effective sampling path. Then, the positions of feature points have been identified and located by the respect of their absolute difference in the finding direction. In the global coordinate, the shape of measured ranged gaps was constructed by critical feature points set based on non-linear least-square method and the geometric dimensional can be also real-time obtained. The experiments on special gap artifact (200 mm×50 mm×32 mm) with freeform curve and multi-scale features were carried out to determine the accuracy and reliability of measuring system, the experimental results indicate that the dimension of gap artifact, including width, depth and flush, were perfectly measured in only 60 s with the resolution less than 0.005 mm and the measuring precision over 0.025 mm. According to the actual operation results, the proposed measuring system is characterized by high automation and high efficiency, and can be well acceptable for application as online dimensional inspection for range gap on freeform shape on the automobile or aerospace production line.