# Estimation of Wind Turbine Blade Icing Volume Based on Binocular Vision
## 3 Experimental Design and Results Analysis
### Volume Estimation Experiment of Regular-Shaped Ice Blocks  
The experiment utilized the HBVCAM-4M2214 HD-2 V11 model binocular stereo vision camera (Huiber Vision Technology Co., Ltd., Shenzhen, China), with its detailed specifications provided in Table 4. This camera satisfies general depth perception requirements and is suitable for target detection and depth measurement. The camera was mounted on an adjustable-height tripod and positioned at a distance of 0.8-0.9 m from the experimental sample to ensure optimal depth measurement accuracy. The camera angle was adjusted to be nearly perpendicular to the surface of the sample to optimize imaging quality. The spatial layout of the experimental setup and the data acquisition system is shown in Figure 9.  
To verify the feasibility and accuracy of stereo vision technology in measuring the volume of ice accretion on wind turbine blades, this paper first conducted volume measurement experiments using ice blocks of regular shapes to evaluate the precision of the measurement method. Subsequently, experiments were carried out to measure the volume of ice accretion on the blades.  
\begin{table}
\begin{tabular}{c c} \hline \hline
**Specification** & **Parameter** \\ \hline Maximum Resolution & \(2688\times 1520\) \\ Sensor Model & OV4689 (\(1/3^{\prime\prime}\)) \\ Supply Voltage & DC \(5\text{V}\pm 5\%\) \\ Operating Temperature Range & \(-30\ ^{\circ}\text{C}\) to \(70\ ^{\circ}\text{C}\) \\ Field of View (FOV) & \(80^{\circ}\) \\ \hline \hline \end{tabular}
\end{table}
Table 4: Parameters of the stereo camera.  
Figure 9: Schematic diagram of the experimental setup’s spatial layout.  
In the preliminary experiments, three ice blocks with different volumes and regular shapes were selected. Their volumes were measured using stereo vision technology, and the measurement errors were calculated. The experimental results are shown in Figure 10.  
As shown in Table 5, the volume measurements of ice blocks with regular shapes verified the feasibility and accuracy of the experimental method. The measurement errors for the three ice blocks with different volumes ranged from 4.85% to 8.35%. The errors mainly originated from volume loss due to ice melting during the experiment, limitations in the precision of measurement tools, and human errors during experimental operations. Larger ice blocks exhibited relatively smaller errors, while smaller ice blocks had higher measurement errors due to a higher surface area to volume ratio, leading to more significant melting losses. Overall, the experimental method demonstrated high accuracy within a certain range, but the error was more pronounced when dealing with small-volume ice blocks. To improve precision, increasing the number of repeated measurements can provide fundamental support for subsequent volume measurements of irregularly shaped objects.  
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**No** & **Volume (mm3)** & **Measured Volume (mm3)** & **Error** \\ \hline
1 & 574,456.52 & 544,133.70 & 5.28\% \\
2 & 427,173.91 & 391,503.49 & 8.35\% \\
3 & 417,391.30 & 397,165.91 & 4.85\% \\ \hline \hline \end{tabular}
\end{table}
Table 5: Volume measurement results and errors.  
Figure 10: Experimental results. (**a1–a3**) Photographs of the physical objects on the left; (b1–b3) Disparity maps; (c1–c3) Point cloud diagrams.