Abstract
Measurement of bridge displacements is important for ensuring the safe operation of railway bridges. Traditionally, contact sensors such as Linear Variable Displacement Transducers (LVDT) and accelerometers have been used to measure the displacement of the railway bridges. However, these sensors need significant effort in installation and maintenance. Therefore, railroad management agencies are interested in new means to measure bridge displacements. This research focuses on mounting Laser Doppler Vibrometer (LDV) on an Unmanned Aerial System (UAS) to enable contact-free transverse dynamic displacement of railroad bridges. Researchers conducted three field tests by flying the Unmanned Aerial Systems Laser Doppler Vibrometer (UAS-LDV) 1.5 m away from the ground and measured the displacement of a moving target at various distances. The accuracy of the UAS-LDV measurements was compared to the Linear Variable Differential Transducer (LVDT) measurements. The results of the three field tests showed that the proposed system could measure non-contact, reference-free dynamic displacement with an average peak and root mean square (RMS) error for the three experiments of 10% and 8% compared to LVDT, respectively. Such errors are acceptable for field measurements in railroads, as the interest prior to bridge monitoring implementation of a new approach is to demonstrate similar success for different flights, as reported in the three results. This study also identified barriers for industrial adoption of this technology and proposed operational development practices for both technical and cost-effective implementation.
Highlights
The U.S railroad network transports up to 40% of the total cross-country freight [1,2]
This study proposes the mounting of an Laser Doppler Vibrometer (LDV) on a Unmanned Aerial System (UAS) for measuring dynamic displacement under train loading, validating, and developing a system through a series of field experiments of different distances and displacements
The two UAS differ in both hardware and software, this exploration waswas conducted forfor preparation purposes and only as exploratory research, given that exploration was conducted forpreparation preparation purposes only as exploratory research, given that exploration conducted purposes andand only as exploratory research, given that there there was no information available about the displacement of using a fixed reference
Summary
The U.S railroad network transports up to 40% of the total cross-country freight [1,2]. The equipment needs to be set up close to the target, and the light conditions need to be ideal for image and video capturing These issues indicate that the use of image processing is not always feasible for railroad bridge displacement measurements in field implementations. Using cameras and other devices mounted on UAS for SHM holds the potential to solve the problems related to accessibility in remote locations and hazardous conditions These methods still require a reference for image processing, postprocessing of the captured data, and algorithms to extract valuable information from the collected data. The output of LDV is less dependent on visibility and atmospheric conditions and is real-time, requiring minimal postprocessing These advantages make the use of LDV ideal for dynamic bridge displacement measurement, it still not reference-free. Barriers of using LDV on an UAS for field applications were identified, and possible solutions for each of the issues were suggested
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
