3-D Measurement of Large Scale Steel Structure

提出了一种新的大尺寸三维测量方法，该方法采用精密准直激光束和五棱镜构成测量坐标。用激光光斑指出待测位置。它们由CCD摄像机检测，坐标由个人计算机计算。以一座100 m以上的悬索桥主塔钢箱形构件的加工精度测量为例，研究了该方法的可行性。最终结构的垂直直线度取决于每个箱形构件端面的平面度和平行度。因此，在端面的最终加工过程中需要高精度的加工，这可以通过“在机测量”成功实现。针对经纬仪、水准仪等传统测量仪器难以实现的问题，将样机安装在一台大型工件端面加工专用机床上，对某塔架钢箱形构件端面进行了加工测量。工件的尺寸约为6m x 6m x 5m。实验结果表明，采用该方法进行在机测量，可显著提高加工精度。例如，所实现的端面的平坦度和不平行度为0.2mm和3x10^<-5>rad。分别

A new measuring method is presented for large scale three dimensional measurement, in which the measurement coordinates are constructed by finely collimated laser beam and pentaprism. The positions to be measured are pointed out with laser spots. They are detected by a CCD-camera and the coordinates are calculated by a personal computer. The feasibility of the presented method is investigated applying a prototype device to the measurement of machining accuracy of steel box members of a main tower of a large suspension bridge.The main tower of a suspension bridge, the height is 100m or more, is built by heaping up many steel box members one over another. The vertical straightness of the final configuration depends of the flatness and parallelism of end surfaces of each box member. Therefore, highly accurate machining is required in the final machining process of the end surfaces, which can be successfully achieved by "on the machine measurement". The conventional surveying instruments, such as theodolite and level, are hardly available for this purpose.The prototype device is installed in a facing machine which is specially designed for machining a large workpiece, and end surfaces of a steel box member of a tower are machined and measured. The size of the workpiece is of around 6m x 6m x 5m. Experimental results verified that the "on the machine measurement" with the presented method can considerably improve the machining accuracy. For instance, the achieved flatness and out-of-parallelism of end surfaces are 0.2mm and 3x10^<-5>rad., respectively.