Developmental Research in a Final Inspection Method for Fabrication of Steel Structures

预先研制的测量系统仅用一台CCD摄像机，每个固定在构件上的靶标必须从不同的点至少测量两次。为了满足这个条件，摄像机被放置在导轨上，摄像机可以沿着该导轨沿着移动。该测量系统具有以下缺陷。(1)大尺寸物体的精确测量需要较长的导轨，这导致测量系统的组装成本较高。(2)角度测量需要一台旋转式千分表和一台高质量的黑格刻度尺。(3)编码器的旋转轴必须由一个精密的机械来支承，而预先研制的测量系统仅用一组CCD摄像机，每个固定在结构件上的靶标必须从不同的点至少测量两次。为了满足这个条件，摄像机组被放置在导轨上，摄像机组可以沿着导轨沿着移动。该测量系统具有以下缺陷。(1)大尺寸物体的精密测量 ...更多信息 需要较长的导轨，并且导致测量系统的组装成本较高。(2)角度测量需要高质量的旋转式千分表和线性尺。(3)编码器的转轴必须由精密机械来承载，本研究尝试以下几项来避免这些缺点。(1)在测量区域配备了两台或多台摄像机，并固定了它们的放置点。设置的位置是这样选择的，每个tagets被不少于两个摄像机组捕捉到。(2)事先精确测量了相邻两组的距离。(3)测量过程中摄像机轴线不移动也不旋转，为了获得足够的精度，深入分析了误差产生的原因，并在实验室设置的检测区域内进行了系统误差的测量。测量结果输入计算机程序，消除系统误差。通过对两个钢桥制作实例的应用，证明了该系统的有效性，从技术和施工两方面来看，该系统是可行的。少

The measuring system developed in advance used only one CCD camera by which each target attached to the structure member must be measured at least tgwice from defferent points. So as to fulfil this condition, the camera is placed on the guide rail along which it can move. This measuring system has the following defects.(1) Precise measuring of a large scale object requires a long guid rail, and it causes high cost for assembling the measuring system.(2) Measuring of angle requires a rotary endoder and a lineer scale of haigh quality.(3) A precision machinery which bears rotating axis of the encoder is indespensable.The measuring system developed in advance used only one CCD camera set by which each target attached to the structure member must be measured at least twice from defferent points. So as to fulfil this condition, the camera setg is place don the guide rail along which it can move. This measuring system has the following defects.(1) Precise measuring of a large scale object re … More quires a long guid rail, and it causes high cost for assembling the measuring system.(2) Measuring of angle requires a rotary endoder and a lineer scale of haigh quaility.(3) A precision machinery which bears rotating axis of the encoder is indespensable.This research attempts the following items to avoid these defects.(1) Dual or more camera sets are furnished to the maeasuring area, and their placing ponits were fixed. The setting positions were so selected every tagets was caught in sight by no less than two camera sets.(2) The distances of the adjacent sets were measured precisely beforhand.(3) The axes of camera were neither moved nor rotated during mesuremtnt.To obtain sufficient precision, causes of errors were searched thotoughly, and the systematic errors were measured in the inspection area settled in the laboratory. The result of mesuring is taken in the computer programs to remove systematic errors. The effeciency was proved by applying this system to two cases of steel bridge fabrication.This research proved that the system propsed is practicable enough, judging form the point of both echonomy and workability. Less