Perspectives on vision-based bridge vibrational monitoring by drones

Vision-based vibrational monitoring aims to extract the modal parameters of civil structures—such as natural frequencies—from recorded video data for Structural Health Monitoring (SHM) purposes. The use of drones for vision-based vibrational monitoring is particularly promising, as drones can access vantage points for video recording that may otherwise be difficult to reach. However, certain drawbacks exist, including potential limitations in resolution, stability, and environmental sensitivity. This paper explores the capabilities, opportunities, and limitations of using drones for vision-based vibrational monitoring. To evaluate technological limits, a target with controlled displacement is used to test various combinations of target distances, displacement amplitudes, and displacement frequencies. Additionally, factors such as environmental conditions and drone hardware are considered. The study defines the practical limits of this approach, aiming to determine the minimum displacement of a vibrating bridge that can be detected by drones. Case studies from the literature are used as benchmarks to identify the dynamic properties of different types of bridges.