# Study of a Small Robot for Mine Hole Detection
## 5 Robot Testing and Analysis  
### Robot Routine Parameter Testing  
The design approach for the small robot used for mine hole inspection involves an initial modular design phase followed by an assembly process. The robot needs to work in a specific environment and, therefore, has strict requirements on its specification parameters. Figure 12 shows the robot's overall experimental system. According to the program design requirements, the mine hole detection small robot needs to complete work in the 70 mm inner diameter of a pipe, so its body size must be manageable. After measurement, the robot's drive arm completely retracts when the outer diameter is the smallest, about 65 mm, and the robot's drive arm fully extends when the outer diameter is up to 100 mm of the total length of 300 mm so that the robot can fit in a pipe with a diameter of 65 mm to 100 mm and complete regular work. A PC pipe with an inner diameter of 70 mm is chosen as the test environment, powered by a 24 V DC/0.4 A power supply, and UM242-type drivers drive the stepper motor. The mine hole-detection small robot uses a cable for power supply and information transmission, and it needs to have a specific traction ability to drag the cable to work. As is shown in Figure 13, the PC pipe is fixed horizontally on the desktop. The diameter of the robot is adjusted to the appropriate size with the variable diameter function. The spring force gauge is connected to the tail of the robot. The spring force gauge is fixed horizontally when the body of the robot is entirely inside the pipe, and the crawling state is stable. The spring force gauge is fixed horizontally and the display of the spring force gauge is the maximum traction force of the robot when the crawling wheel is stagnant or when there is obvious slipping after many measurements. The results show that the average maximum traction force of the robot can reach 40 N.  
Flammable gases such as methane are present in coal mine boreholes, so the current and power of the small robot for mine hole detection cannot be too large. Table 1 shows  
Figure 12: The robot integral test system. Figure 13: Traction test. the parameters of the robot. The maximum drive current of the robot is 0.4 A, and the maximum power is 12 W, which meet the actual demand. ### Robot Routine Parameter Testing  
Given that mine holes are not always horizontal, a small robot designed for mine hole inspections must be able to climb and maintain an appropriate speed. Both the crawling speed and climbing ability of this mine hole-inspection robot were tested. As shown in Figure 14, a vertical scale is affixed to one end of the PC pipe. We calculated the height to which the PC pipe can be lifted at various angles and recorded these measurements on the vertical scale. Starting from the horizontal position, we gradually lifted the PC pipe, timing how long it took for the robot to traverse the pipe at each angle. This allowed us to indirectly measure the robot's crawling speed on varying slopes. After the measurement, we determined that the maximum crawling speed of the robot is 3.96 m/min and the maximum crawling slope is 90\({}^{\circ}\). Crawl times are hand-recorded with a maximum error of 0.3%. Figure 15 shows the fitting analysis of the experimental results. The speed of the robot increases with the angle, and the attenuation is only 0.592%; thus, it can be considered that the crawling speed of the robot is more stable and has good adaptability. There is no strict standard for the propulsion speed of the coal mine hole-detection instrument, and it needs to be changed flexibly according to the actual situation in different mines. It is generally required that the propulsion speed of the instrument should be at most 6 m/min. Therefore, a robot of this design can meet the actual requirements.