# Automatic Reading Algorithm of Substation Dial Gauges Based on Coordinate Positioning
## 4 Conclusions  
In this paper, a dial gauge automatic recognition algorithm based on coordinate positioning is proposed, which can be applied in inspected robots in complex background environment. This method is not affected by background factors, and accurate readings can be obtained by directly extracting the center of the circle and the point coordinates on the positioning pointer from the dial. Firstly, the MSRCR algorithm is used to reduce the impact of lighting, which is good for the later experimental steps to extract coordinates accurately. Secondly, the meter's center is recognized by using the circle detection method based on the arc-support line segment. Then, the pointer can be extracted by constructing a pointer-free template, and the concentric circle algorithm is used for the refined pointer result, which achieves the purpose of positioning the pointer accurately. Finally, the angle method is used to realize automatic reading. The experimental results show that the proposed algorithm is fast, accurate, less affected by light and has a strong anti-interference ability against the background image of the dashboard.  
Conceptualization, D.L. and W.L.; methodology, D.L. and W.L.; software, X.Y.; validation, D.L., W.L. and Q.G.; formal analysis, Q.G. and Y.S.; investigation, Y.S.; resources, Q.G.; data curation, X.Y.; writing--original draft preparation, D.L. and W.L.; writing--review and editing, X.Y. and Q.G.; visualization, Q.G.; supervision, Y.S.; project administration, Y.S.; funding acquisition, X.Y. All authors have read and agreed to the published version of the manuscript.  
\begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline \multirow{2}{*}{**Number**} & **Reading by** & **Reading by** & **Relative** & **Reading by** & **Relative** & **Reading by** & **Relative** \\  & **Human** & **Method in** & **Error(\%)** & **Method in** & **Error(\%)** & **our Method** & **Error(\%)** \\ \hline
1 & 0.386 & 0.372 & 3.627 & 0.390 & 1.058 & 0.379 & 0.707 \\
2 & 0.413 & 0.398 & 3.499 & 0.417 & 1.121 & 0.404 & 0.944 \\
3 & 0.397 & 0.373 & 5.893 & 0.391 & 1.409 & 0.412 & 1.530 \\
4 & 0.141 & 0.164 & 2.339 & 0.143 & 1.637 & 0.157 & 1.612 \\
5 & 0.179 & 0.172 & 3.494 & 0.181 & 1.569 & 0.165 & 1.408 \\
6 & 0.383 & 0.405 & 2.245 & 0.386 & 0.977 & 0.388 & 0.501 \\
7 & 10.25 & 10.401 & 15.116 & 10.138 & 1.096 & 10.241 & 0.916 \\
8 & 0.59 & 0.544 & 7.748 & 0.582 & 1.316 & 0.603 & 1.287 \\
9 & 2.49 & 2.137 & 14.184 & 2.466 & 0.967 & 2.485 & 0.541 \\
10 & 2.45 & 2.573 & 12.291 & 2.429 & 0.852 & 2.445 & 0.498 \\ Average & / & / & 7.044 & / & 1.200 & / & 0.994 \\ \hline \hline \end{tabular}
\end{table}
Table 5: Measurement readings of ten dial gauges using four methods.  
**Funding:** This research was funded by The Natural Science Foundation of Tianjin (No.18 JCQNJC01000), the National Natural Science Foundation of China (No.61502340), Scientific Research Project of Tianjin Education Commission (No.2018 KJ133) and Open Funds of Tianjin Key Laboratory for Control Theory & Applications in Complicated Systems (No. TJKL-CTACS-201907).  
**Institutional Review Board Statement:** Not applicable.  
**Informed Consent Statement:** Not applicable.  
**Data Availability Statement:** The data presented in this study are available in the manuscript.  
**Conflicts of Interest:** The authors declare no conflict of interest.