Deflection measurements on structures continue to be a challenge with current sensor technologies. Material degradation and changes in the mechanical properties over time (e.g. creep and shrinkage in concrete bridges) directly impact the deflections exhibited by a structure. In this article, we introduce and discuss the evaluation of a novel laser- and video-based displacement sensor prototype to monitor displacements and rotations on structures remotely. The sensor is inexpensive, using off-the shelf components, but also accurate and practical for situations that do not allow the use of conventional displacement sensors, which require a reference base. In contrast to other image-based approaches such as digital image correlation (DIC) or Eulerian-based virtual video sensors (VVS), the digital camera of our proposed solution is located at the measurement location on the structure. The sensor was evaluated using laboratory tests to determine the practicality, accuracy, and sensitivity to lighting conditions. The accuracy of the sensor was found to be approximately ± 0.9 mm (± 0.035 in) (95% prediction limits) for a 30.5 m (100 ft) measurement distance under laboratory conditions. Finally, we applied and evaluated the sensor under real-world conditions on a concrete deck/single steel box girder pedestrian bridge under static and dynamic loading conditions as well as on a five-story steel moment-frame building under ambient conditions. Essential for field applications, the results demonstrate the prototype offers an inexpensive yet practical and accurate solution for monitoring displacements and rotations remotely.

对结构的挠度测量仍然是当前传感器技术面临的挑战。材料的降解和机械性能随时间的变化（例如，混凝土桥梁的蠕变和收缩）直接影响结构所表现出的挠度。在本文中，我们介绍并讨论了基于激光和视频的新型位移传感器原型的评估，该原型可远程监视结构上的位移和旋转。该传感器价格便宜，使用现成的组件，但是对于不允许使用需要参考基座的常规位移传感器的情况，该传感器也很精确和实用。与其他基于图像的方法（例如数字图像相关性（DIC）或基于欧拉的虚拟视频传感器（VVS））不同，我们提出的解决方案的数码相机位于结构的测量位置。使用实验室测试对传感器进行评估，以确定实用性，准确性和对光照条件的敏感性。在实验室条件下，对于30.5 m（100 ft）的测量距离，发现传感器的精度约为±0.9毫米（±0.035英寸）（95％的预测极限）。最后，我们在静态和动态载荷条件下的混凝土甲板/单钢箱梁人行天桥上以及在环境条件下的五层钢框架结构中，在实际条件下应用并评估了传感器。对于现场应用至关重要，结果表明该原型为远程监控位移和旋转提供了一种廉价而又实用且准确的解决方案。