# Horizontal Bending Angle Optimization Method for Scraper Conveyor Based on Improved Bat Algorithm
## 5 Experiment and Application  
The horizontal bend angle optimization system for the S-bending area of the scraper conveyor based on the proposed method was experimentally applied to the fully mechanized mining face, as shown in Figure 7. The application was tested at the 21220 working face of Changcun Mine of Henan Da You Energy Co., Ltd. Since the current of the scraper conveyor can intuitively reflect the load [35], combined with the relationship between the \(\alpha^{\prime}\) and the load analyzed in Section 2.1, the optimal value of the \(\alpha^{\prime}\) could be verified by collecting the current consumed by scraper conveyor. The current transformer was used to collect the current of the head and tail of the scraper conveyor, and the data were transmitted through the wireless MESH network installed on the hydraulic support. The ground monitoring center was used for remote monitoring and control. \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Compared Methods** & **Serial Number** & **1** & **2** & **3** \\ \hline \multirow{3}{*}{**MBA**} & \(S_{score\_\_\_}\)max & 92.396 & 92.396 & 92.396 \\  & Mean (\({}^{\circ}\)) & 0.660 & 0.660 & 0.664 \\  & SD (\%) & 1.0 & 0.6 & 0.7 \\ \hline \multirow{3}{*}{**ABAM**} & \(S_{score\_\_}\)max & 92.395 & 92.394 & 92.396 \\  & Mean (\({}^{\circ}\)) & 0.657 & 0.659 & 0.661 \\  & SD (\%) & 2.0 & 2.5 & 1.8 \\ \hline \multirow{3}{*}{**BCBA**} & \(S_{score\_\_}\)max & 92.396 & 92.395 & 92.396 \\  & Mean (\({}^{\circ}\)) & 0.650 & 0.660 & 0.657 \\  & SD (\%) & 3.0 & 2.7 & 1.9 \\ \hline \multirow{3}{*}{**BAO**} & \(S_{score\_\_}\)max & 92.394 & 92.395 & 92.396 \\  & Mean (\({}^{\circ}\)) & 0.640 & 0.664 & 0.662 \\  & SD (\%) & 3.2 & 3.3 & 1.9 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: The performance comparison results of the four different algorithms. The current required by the scraper conveyor varied with the \(\alpha^{\prime}\). When \(\alpha^{\prime}=1.5^{\circ}\), the current consumption of the motor was about 7 A larger than that of \(\alpha^{\prime}=0.5^{\circ}\) and \(0.66^{\circ}\). When \(\alpha^{\prime}=0.66^{\circ}\), the current consumption of the scraper conveyor drive motor was 2 A larger than \(\alpha^{\prime}=0.5^{\circ}\). To verify the accuracy and practicality of the proposed method, the average absolute error was used. The average absolute error calculation results are shown in Table 4.  
Under the three different \(\alpha^{\prime}\), the maximum and minimum average absolute errors of the actual-theoretical current were 3.68% and 2.11%, respectively. The average absolute error of \(\alpha^{\prime}\)  
Figure 8: Comparison between the measured and theoretical current of scraper conveyor when \(m=1\). Figure 9: Comparison between the measured and theoretical current of scraper conveyor when \(m=2\). = 0.66\({}^{\circ}\) was smaller than that of \(\alpha^{\prime}\) = 0.5\({}^{\circ}\) and 1.5\({}^{\circ}\). The error between the theoretical calculation and experimental data was very small, and the trend of increase and decrease was consistent. When \(\alpha^{\prime}\) = 0.5\({}^{\circ}\), the S-bending area was so long that the efficiency of the shearer's level cutting was very low, and the hydraulic support could not be timely supported. Although the scraper conveyor consumed less current when \(\alpha^{\prime}\) = 0.5\({}^{\circ}\), the time for the shearer to cut a knife coal was increased by 20%, and the MTBF was raised by 15%. Therefore, \(\alpha^{\prime}\) = 0.5\({}^{\circ}\) was unacceptable. In other words, the mining model with smaller \(\alpha^{\prime}\) was not good. The horizontal bending angle \(\alpha^{\prime}\) was changed to 0.66\({}^{\circ}\) and used under the mine for one year. The replacement frequency of the sprocket assembly was reduced by 50%, which saved about $284,000. The total electricity consumption of the working face was reduced by 31%, thus $97,000 was saved. Due to the decrease of MTBF, production time increased, and 32,000 more tons of coal were produced than the previous year.