Vicente Miguel A, Gonzalez Dorys C, Minguez Jesus, Schumacher Thomas
Department of Civil Engineering, University of Burgos, c/Villadiego, s/n. 09001 Burgos, Spain.
Department of Civil Engineering, Parks College of Engineering, Aviation and Technology, Saint Louis University, 3540 Lindell Blvd, Saint Louis, MO 63103, USA.
Sensors (Basel). 2018 Mar 25;18(4):970. doi: 10.3390/s18040970.
The measurement of static vertical deflections on bridges continues to be a first-level technological challenge. These data are of great interest, especially for the case of long-term bridge monitoring; in fact, they are perhaps more valuable than any other measurable parameter. This is because material degradation processes and changes of the mechanical properties of the structure due to aging (for example creep and shrinkage in concrete bridges) have a direct impact on the exhibited static vertical deflections. This paper introduces and evaluates an approach to monitor displacements and rotations of structures using a novel laser and video-based displacement transducer (LVBDT). The proposed system combines the use of laser beams, LED lights, and a digital video camera, and was especially designed to capture static and slow-varying displacements. Contrary to other video-based approaches, the camera is located on the bridge, hence allowing to capture displacements at one location. Subsequently, the sensing approach and the procedure to estimate displacements and the rotations are described. Additionally, laboratory and in-service field testing carried out to validate the system are presented and discussed. The results demonstrate that the proposed sensing approach is robust, accurate, and reliable, and also inexpensive, which are essential for field implementation.
桥梁静态竖向挠度的测量仍然是一项一级技术挑战。这些数据极具价值，特别是对于长期桥梁监测而言；事实上，它们可能比任何其他可测量参数都更有价值。这是因为材料退化过程以及结构因老化导致的力学性能变化（例如混凝土桥梁中的徐变和收缩）会直接影响所表现出的静态竖向挠度。本文介绍并评估了一种使用新型基于激光和视频的位移传感器（LVBDT）来监测结构位移和旋转的方法。所提出的系统结合了激光束、LED灯和数字摄像机的使用，并且专门设计用于捕捉静态和缓慢变化的位移。与其他基于视频的方法不同，摄像机位于桥梁上，从而能够在一个位置捕捉位移。随后，描述了传感方法以及估计位移和旋转的过程。此外，还介绍并讨论了为验证该系统而进行的实验室测试和现场实际测试。结果表明，所提出的传感方法稳健、准确且可靠，而且成本低廉，这对于现场应用至关重要。
