基于无人飞机成像的桥梁裂缝宽度识别可行性研究

基于传统桥梁检测车裂缝宽度检测存在阻碍交通、受到桥型限制、使用维护费用高等问题。该文以旋翼无人飞机为工作平台，为满足0.2mm以上桥梁裂缝宽度识别要求，采用IMETRUM非接触式测量仪验证无人机悬停状态下机载成像质量具有可靠性；通过加装机载三点激光测距仪，测量物距并推导成像平面与被测平面夹角，计算并修正裂缝图像像素解析度；设计适于无人机成像的图像预处理程序、构建基于支持向量机（SVM）裂缝形态智能提取训练模型、裂缝法向实际宽度计算方法。以湘潭市湘江二大桥为研究对象，通过对实桥进行无人机裂缝宽度识别，并与传统人工测试进行比较，表明机载成像识别裂缝宽度满足工程精度要求，以无人飞机为工作平台替代桥检车或支架工作平台，实现结构表面裂缝形状与宽度识别具有可行性和广泛应用前景。

Study on the feasibility of identifying concrete crack width with images acquired by unmanned aerial vehicle

Aiming at the serious problems incurred by the traditional bridge detection vehicle, including obstructing the traffic, being restricted by bridge type, and high maintenance cost, the research was conducted. The unmanned aerial vehicles (UAV) were used for the imaging platform, and the good imaging quality of unmanned aerial vehicles in a hovering state can be proved by making use of the IMETRUM non-contact measurement instrument, according to the imaging quality requirement of above 0.2mm for identification of crack width. By installing three point laser rangefinder to measure the object distance and derive the angle between the imaging plane and the measured plane, the pixel resolution can be calculated and corrected. The image preprocessing program suitable for UAV imaging is designed, the intelligent extraction training model of crack shape based on support vector machine (SVM) is established, and the calculation method for crack width along normal direction is proposed. With the second bridge of Xiangjiang river in Xiangtan taken as an example, the identification of crack width based on UAV is carried out for the real bridge, and then compared with that of the traditional manual test. It is found that the crack width identified by UAV imaging meets the engineering accuracy requirement, and the unmanned aircraft as the working platform to replace the bridge inspection car or support platform is feasible and promising in identifying the shape and width of cracks on the surface of the structure.