## 2 UAV and LDV Selection  
There are two main types of UAVs: fixed-wing and multi-rotor. Fixed-wing UAVs are mainly suitable for long-duration, long-range, and wide-area flight operations [51]. They have high-speed flight capability, longer endurance, and larger load capacity, making them suitable for agricultural and environmental missions. Multi-rotor UAVs are designed for tasks that require small-scale, aerial hovering, and minor space shuttling capabilities [52]. They consist of multiple rotor blades, enabling vertical takeoff and landing, and hovering in the air. These characteristics enable the systems to be suitable for energy surveying, electrical power inspection, etc. Consequently, they are more commonly employed in detailed image acquisition and inspection of stationary structures, such as power lines and wind turbines.  
Multi-rotor UAVs are preferred in this study owing to their excellent weight-carrying capability for carrying equipment such as LDVs. Additionally, they can hover steadily and align themselves with the measuring points to obtain the acceleration time history during the test. The advanced DJI Mavic 3 was then chosen for testing due to its potential use in curtain wall inspection. Table 1 shows the specifications, and Figure 1a,b illustrate its appearance, respectively. The vibration signal of HFSGCW is measured using the LDV(MV-H100) from OMNISENSING PHOTONICS in China. Figure 1c depicts the appearance of the LDV and Table 2 shows the specifications of it.  
Figure 2 shows the constructed testing system. The LDV is first attached to the bracket using a carbon fiber plate and stainless-steel screws. Then, the bracket is fitted onto the UAV's fuselage. A system for acquiring acceleration time history is constructed by combining the selected UAV and LDV. The LDV directly captures and transmits signals to a PC for analysis, enabling efficient detection of acceleration time history at high altitudes without an additional data acquisition system, as it is an integrated device.  
\begin{table}
\begin{tabular}{c c} \hline
**Specific Items** & **Specifications** \\ \hline Bare Weight & 895 g \\  & Folded (without propellers) 221 \(\times\) 96.3 \(\times\) 90.3 mm \\ Dimensions (Folded/Unfolded) & (Length \(\times\) Width \(\times\) Height) \\  & Unfolded (without propellers) 347.5 \(\times\) 283 \(\times\) 107.7 mm \\  & (Length \(\times\) Width \(\times\) Height) \\ Max Flight Time (no wind) & 46 min \\ Max Hovering Time (no wind) & 40 min \\ Max Wind Speed Resistance & 12 m/s \\ Operating Temperature & \(-10^{\circ}\) to \(40^{\circ}\) C (\(14^{\circ}\) to \(104^{\circ}\) F) \\ GNSS & GPS + Galileo + BeiDou \\  & Vertical: \(\pm\) 0.1 m (with Vision Positioning); \(\pm\) 0.5 m \\ Hovering Accuracy Range & (with GNSS Positioning) \\  & Horizontal: \(\pm\) 0.3 m (with Vision Positioning); \(\pm\) 0.5 m \\ Maximum Take-off Weight with Payload & 1200 g \\ \hline \end{tabular}
\end{table}
Table 1: DJI Mavic 3 specifications.  
\begin{table}
\begin{tabular}{c c c c c c} \hline
**Frequency** & **Laser** & **Displacement** & **Maximum** & **Displacement** & **Output Signal** & **Weight** \\
**Range** & **Wavelength** & **Resolution** & **Speed Range** & **Repeatability** & **Output Signal** & **Weight** \\ \hline DC-2.5 MHz & 1310 mm & 1.28 nm & 1500 mm/s & 10 nm & Digital & 213.7 g \\ \hline \multicolumn{5}{c}{Weight of the bracket} & \multicolumn{5}{c}{Weight of the system} \\  & 90.2 g & & 1198.9 g \\ \hline \end{tabular}
\end{table}
Table 2: LDV specifications and weight of the system.  
Figure 1: Instruments. (**a**) Unfolded form. (**b**) Folded form. (**c**) LDV.