# Study of a Small Robot for Mine Hole Detection
## 6 Conclusions  
With the increase in coal mining resources, mining operations in complex areas have increased. However, these areas were characterized by complicated hydrogeological conditions, which result in issues such as water damage, collapses, roof collapses, and other mining-related accidents. The deployment of mine hole-detection technology proved effective in minimizing such accidents. In this study, we aimed to examine the shortcomings of existing mine hole-inspection technologies and propose a configuration for a small mine hole-inspection robot specifically designed to operate in the complex environment found in coal mines. The robot had a radial diameter of 65 mm, making it suitable for small bores ranging from 65 mm to 100 mm in size. Notably, it exhibited excellent crawling performance and a low power consumption of only 12 W. Additionally, it was equipped with waterproof, explosion-proof, and variable-diameter capabilities, allowing it to adapt to the complex conditions encountered in coal mine boreholes. This robot provides essential technical support for the detection of coal mine boreholes. The main research work of this paper is as follows:  
1. The functional analysis and structural design of a small robot for mine hole inspection were carried out according to engineering requirements. The variable-diameter function was designed to adapt to the unevenness of mine holes. The force situation was theoretically analyzed, and the optimal parameters of the critical structure were calculated to ensure the working life of the robot.
2. Using three-dimensional modeling software, the structural model of the small robot for mine hole detection was established. The gear structure was used to reduce the radial size of the robot to adapt to the small diameter of a mine hole; the buffer structure was set to improve the shooting quality and passability; and the gimbal structure was designed to facilitate the expansion of the robot.
3. The small robot's hardware circuit and control program for mine hole detection were designed to focus on the waterproof and explosion-proof design to address the problem of water and gas inside the mine hole. The power of the whole machine was limited to no more than 12 W, which met the engineering requirements.
4. The mine hole detection small robot was tested, and the test results showed that the mine hole detection small robot worked within a hole diameter of 65 mm to 100 mm and had a maximum power of 12 W, a top crawling speed of 3.96 m/min, and a maximum crawling slope of 90\({}^{\circ}\). The experimental results demonstrated that the mine hole-detection robot could adapt to the coal mine hole environment and meet engineering needs.  
Conceptualization, L.G. and H.L.; investigation, Z.F. and L.Z.; methodology, W.Z. and X.X.; supervision, L.G., H.L. and X.X.; validation, Z.F. and L.Z.; writing--original draft, Z.F. and L.Z. All authors have read and agreed to the published version of the manuscript.  
This research was funded by the State Key Laboratory of Gas Disaster Detecting Open Fund, grant number 2021 SKLKF11; the National Natural Science Foundation of China, grant number 51974273; the National Natural Science Foundation of China, grant number 52374234; the Natural Science Starting Project of SWPU, grant number 2023 QHZ003; the Sichuan Provincial Science and Technology Plan Project, grant number 2023 ZHCG0020; and the Nanchong City--Southwest Petroleum University City-School Science and Technology Strategic Cooperation Project, grant number 23 XNSYSX0022/23 XNSYSX0026.  
Not applicable.  
Data Availability Statement: Data are contained within this article.  
Hearfelt thanks to those who helped with this research.  
Conflicts of Interest:Author [PERSON] is employed by the company \"China Coal Technology & Engineering Group Corp\". The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as potential conflicts of interest.