This work demonstrates the viability of using a smartphone-based vision system to monitor the deflection of engineering structures subjected to external loadings. The video images of a test structure recorded by a smartphone camera are processed using the state-of-the-art subset-based digital image correlation (DIC) algorithm to extract the vertical image displacement of discrete calculation points defined on the test object. The measured vertical image displacement can be converted to deflection (vertical displacement) by easy-to-implement scaling factor determination approaches. For accuracy validation, laboratory experiments using a cantilever beam subjected to external loadings were performed. The deflection and inherent frequency of the test cantilever beam measured by the proposed smartphone-based vision system were compared with those measured by conventional dial gauges and a dynamic strain gauge. The relative errors were estimated as 1% and 0.15% for deflection and inherent frequency, respectively. Outdoor real bridge deflection monitoring tests were also carried out on an overpass with subway passing by, and the measured deflection-time curves agree well with actual situations. The cost-effective, ultraportable, and easy-to-use smartphone-based vision system not only greatly decreases the hardware investment and complexity in deflection measurement system construction, but also increases the convenience and efficiency of deflection monitoring of engineering structures.

中文翻译：

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具有成本效益且基于智能手机的超便携式视觉系统，用于结构变形监控

这项工作证明了使用基于智能手机的视觉系统来监控承受外部载荷的工程结构的挠曲性的可行性。使用最新的基于子集的数字图像相关性（DIC）算法处理由智能手机相机记录的测试结构的视频图像，以提取在测试对象上定义的离散计算点的垂直图像位移。可以通过易于实现的比例因子确定方法将测得的垂直图像位移转换为挠度（垂直位移）。为了验证准确性，进行了使用悬臂梁承受外部载荷的实验室实验。拟议的基于智能手机的视觉系统测得的悬臂梁的挠度和固有频率与常规千分表和动态应变仪测得的挠度和固有频率进行了比较。挠度和固有频率的相对误差分别估计为1％和0.15％。还在经过地铁的高架桥上进行了室外实际桥梁挠度监测测试，测得的挠度-时间曲线与实际情况吻合得很好。具有成本效益，超便携且易于使用的基于智能手机的视觉系统，不仅大大减少了挠度测量系统构建的硬件投资和复杂性，而且还增加了对工程结构进行挠度监测的便利性和效率。挠度和固有频率的相对误差分别估计为1％和0.15％。还在经过地铁的高架桥上进行了室外实际桥梁挠度监测测试，测得的挠度-时间曲线与实际情况吻合得很好。具有成本效益，超便携且易于使用的基于智能手机的视觉系统，不仅大大减少了挠度测量系统构建的硬件投资和复杂性，而且还增加了对工程结构进行挠度监测的便利性和效率。挠度和固有频率的相对误差分别估计为1％和0.15％。还在经过地铁的高架桥上进行了室外实际桥梁挠度监测测试，测得的挠度-时间曲线与实际情况吻合得很好。具有成本效益，超便携且易于使用的基于智能手机的视觉系统，不仅大大减少了挠度测量系统构建的硬件投资和复杂性，而且还增加了对工程结构进行挠度监测的便利性和效率。测得的挠曲时间曲线与实际情况吻合良好。具有成本效益，超便携且易于使用的基于智能手机的视觉系统，不仅大大减少了挠度测量系统构建的硬件投资和复杂性，而且还增加了对工程结构进行挠度监测的便利性和效率。测得的挠曲时间曲线与实际情况吻合良好。具有成本效益，超便携且易于使用的基于智能手机的视觉系统，不仅大大减少了挠度测量系统构建的硬件投资和复杂性，而且还增加了对工程结构进行挠度监测的便利性和效率。