Measuring Transverse Displacements Using Unmanned Aerial Systems Laser Doppler Vibrometer (UAS-LDV): Development and...

Area of Science:

• Civil Engineering
• Geophysics
• Aerospace Engineering

Background:

• Traditional contact sensors like Linear Variable Displacement Transducers (LVDT) and accelerometers require significant installation and maintenance for railway bridge displacement monitoring.
• Railroad management agencies seek advanced, less intrusive methods for assessing bridge integrity and safety.

Purpose of the Study:

• To investigate the feasibility of using a Laser Doppler Vibrometer (LDV) mounted on an Unmanned Aerial System (UAS) for non-contact measurement of transverse dynamic displacements on railway bridges.
• To evaluate the accuracy and practical applicability of the UAS-LDV system compared to traditional LVDT measurements.

Main Methods:

• Field tests were conducted using a UAS equipped with an LDV, flying at a height of 1.5 meters.
• The UAS-LDV system measured the dynamic displacement of a moving target on a railway bridge.
• Measurements were cross-validated against data from a simultaneously deployed LVDT.

Main Results:

• The UAS-LDV system demonstrated successful non-contact, reference-free dynamic displacement measurement.
• Average peak error was 10% and root mean square (RMS) error was 8% when compared to LVDT measurements across three field tests.
• The achieved accuracy is considered acceptable for practical field measurements in railway bridge monitoring.

Conclusions:

• The UAS-LDV system presents a viable alternative to traditional contact sensors for railway bridge displacement monitoring.
• The study identified key barriers to industrial adoption and proposed strategies for technical and cost-effective implementation.
• This technology has the potential to enhance the safety and efficiency of railway bridge inspection and maintenance.