## 4 UAV Experiments  
### UAV Experiment in Lab  
When a UAV's on-board camera is used to record video, during flight in the air, the UAV is likely to be influenced by air currents and wind, causing the fuselage to drift and shake. To verify the reliability of the improved method in removing the noise generated by the UAV, comparative experiments were carried out both before and after noise elimination. The experimental setup is illustrated in Figure 12.  
The experimental configuration was as follows: The MTS hydraulic system was made to vibrate at frequencies of 0.5 Hz and 1 Hz, respectively, with the amplitude set at 10 mm. The UAV was operated, and the camera mounted on the UAV captured the vibration video at a frame rate of 30 frames per second. The experimental equipment is depicted in Figure 13.  
\begin{table}
\begin{tabular}{c c c c c} \hline
**ROI** & **Min Pt Region1** & **Max Pt Region1** & **Min Pt Region2** & **Max Pt Region2** \\ \hline Before elimination & 59.7\% & 65.2\% & 56.1\% & 70.4\% \\ After elimination & 97.7\% & 98.6\% & 96.2\% & 95.7\% \\ \hline \end{tabular}
\end{table}
Table 5: Comparison of accuracy of region of interest computation (3 Hz) after eliminating camera vibration with the improved LK method with a threshold of 0.3\(\times\)\(\sigma\).  
Figure 12: Set up of the UAV experiment.  
The test results at a frequency of 0.5 Hz are presented in Figure 14. Owing to the instability of the UAV's hovering flight, when the UAV moves away from the MTS, the horizontal distance between the UAV and the vibrating object increases, which leads to a relatively small amplitude of the curves from 0 to 2 s. As illustrated in Figure 15, there is an increase in the horizontal distance from the vibrating object during the movement away from the MTS. Conversely, when the UAV approaches the MTS, the horizontal distance from the vibrating object decreases, causing the amplitude of the curve to be larger in the time interval of 2 to 4 s. Through a comparison with the curves of the MTS, it can be seen that the data obtained after noise removal using the improved method are accurate.  
As presented in Table 6, the accuracy prior to the elimination of the UAV's wobble was approximately 89.9%, and after the elimination, it reached around 98.2%, marking an improvement of 8.3%.  
The test results at 1 Hz are shown in Figure 12. When the horizontal distance between the UAV and the object changes significantly, the improved method is still capable of effectively eliminating the noise and yielding accurate results.  
As shown in Table 7, the accuracy before eliminating drone drift was only about 44.3% and after eliminating it was about 98.3%, an improvement of 54.0%, due to the drone's violent shaking.  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**ROI** & **Min Pt Region1** & **Max Pt Region1** & **Min Pt Region2** & **Max Pt Region2** \\ \hline Before elimination & 90.4\% & 88.3\% & 93.3\% & 87.5\% \\ After elimination & 97.9\% & 99.1\% & 98.0\% & 97.9\% \\ \hline \hline \end{tabular}
\end{table}
Table 6: Accuracy Comparison of Region of Interest Calculation for Improved LK Method After UAV Wobble Elimination (0.5 Hz).  
Figure 13: Equipment for the experiment.