## 5 Experimental Validation  
To verify the feasibility and accuracy of the steel belt-anchor hole positioning method designed for a drilling and anchoring robot based on monocular vision presented in this paper, an experimental platform for steel belt anchor hole pose measurements was built in the laboratory, as shown in Figure 7. The experimental platform consists of a computer, steel belt-anchor hole pose visual measurement unit, coal wall model, steel belt model, and related measurement instruments. Among them, the steel belt-anchor hole pose visual measurement unit consists of an MV_EM120C industrial camera, three laser pointers, and a mounting bracket. The camera has a resolution of 1280 \(\times\) 960 and a focal length of 5 mm. It is primarily used to capture images of the anchoring holes on the steel belt and the laser spots on the coal wall. The laser pointer is a device used for field measurements in mining, primarily for positioning and targeting in mine tunneling and railway tunnels, providing a collimated beam. In harsh underground environments with dust, coal dust, fog, moisture, and heavy water spray, it exhibits strong penetration capabilities and produces a clearly visible spot. This study employs a red laser with a wavelength of 660 nanometers. The coal wall model is installed vertically on the ground; the steel belt model is fixed horizontally on the coal wall; and the related measurement instruments include a total station and an inclination sensor. The total station is used to determine the parameters of the steel belt-anchor hole pose visual measurement unit and its relative position to the steel belt anchor hole, and the inclination  
Figure 6: Extraction results of steel belt anchor hole center: (**a**) original image; (**b**) image after binarization; (**c**) image after edge extraction; (**d**) results of feature extraction. sensor is used to determine the relative attitude between the steel belt-anchor hole pose visual measurement unit and the steel belt anchor hole, which has a range of 0-360\({}^{\circ}\) with an accuracy of 0.01\({}^{\circ}\). For the experiment, the total station's coordinate system \(O_{0}X_{0}Y_{0}Z_{0}\) is first established at an appropriate location as the unified position reference for the experiment. Then, the camera axis of the steel belt-anchor hole pose visual measurement unit is kept in the Y\({}_{0}\)O\({}_{0}Z_{0}\) plane of the total station's coordinate system, and the external reference between the camera and the three laser pointers in the steel belt-anchor hole pose visual measurement unit is calibrated, as shown in Figure 8.  
Figure 8: Schematic diagram of the parameter calibration method of the steel belt anchor hole pose visual measurement unit. Figure 7: Experimental platform used for steel belt anchor hole pose measurements. For the calibration, the coordinates of the camera's optical center \(O_{C}\), laser pointer center \(P_{i}\), and a point \(Q_{i}\) on the laser ray are determined by the total station; the coordinates of \(P_{i}\) and \(Q_{i}\) under the camera's coordinate system are obtained by coordinate system conversion; and the direction vector \(S_{L_{i}}\) of straight line \(L_{i}\) is further obtained, which is the external reference of the camera and laser pointers in the steel belt-anchor hole pose visual measurement unit. The results of the external reference calibration are shown in Table 2.  
The experimental platform used for anchoring-hole pose detection was constructed in the laboratory. A smoke generator was used to simulate the high dust environment of an underground coal mine. Indoor lighting was turned off, blackout curtains were employed, and experimental personnel wore mining lamps to simulate the low and uneven illumination typical of coal mine roadways. This setup aimed to mimic the high dust and low illumination conditions as closely as possible.