## 3 Results
### Experimental Results
#### 3.2.1 Pose Detection and Measurement Experiment  
The experiment must be started at a distance of 10 m, and the laser emitter must be adjusted so that the laser plane is perpendicular to the ground and consistent with the reference line. By adjusting the pose of the crawler robot, the spot position coordinates of the two laser receivers are zero, and the state at this time can be taken as the initial state. The pose of the crawler robot should be changed, and then the steel ruler and high-precision goniometer used to measure the yaw angle and the lateral deviation of the roadheader as the actual value. Comparison of the measured value of the navigation system with the actual value provides the measurement error. These experimental steps were repeated 20 times to obtain a plurality of measurement errors and obtain the standard deviation of the measurement error. The distance between the crawler robot and the laser emitter must be increased at 10 m intervals each time, and then the experimental steps repeated. The measurement error of attitude parameters is shown in Figure 15.  
Within the range of 10-80 m, the X-axis coordinate measurement error generally increases with the increase in distance, the standard deviation of error is between 1-6 mm, \begin{table}
\begin{tabular}{c c} \hline \hline
**Parameter Setting** & **Set Value** \\ \hline Operating voltage/V & 12-24 \\ Operating current/mA & \(\leq\)15 \\ Measuring range/\({}^{\circ}\) & \(-\)90–90 \\ Baud rate/bps & 57,600 \\ Measurement accuracy/\({}^{\circ}\) & \(\pm\)0.5 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Inclination sensor parameters. Figure 15: The measurement error of the pose parameter. \begin{table}
\begin{tabular}{c c} \hline \hline
**Parameter Setting** & **Set Value** \\ \hline Effective Distance/m & 100 \\ Laser wavelength/nm & 530 \\ Emitted power/mW & 15 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Laser receiver parameters. and the maximum error is between 3-10 mm. The Y-axis coordinate measurement error generally increases with the increase in distance, the standard deviation of error is between 4-14 mm, and the maximum error is between 10-32 mm. The measurement error of yaw angle does not obviously change with distance. The standard deviation of error is between 0.1-0.3\({}^{\circ}\), and the maximum error is between 0.25-0.65\({}^{\circ}\). After the completion of the ground test, in order to further verify the reliability of the navigation system under the actual working conditions, a downhole industrial test was carried out. The test site is shown in Figure 16.  
The northeast celestial coordinate system is adopted in the mining area to indicate the direction of the roadheader. The reference system (navigation coordinate system) is defined as the X-axis representing the east, the Y-axis representing the north and the Z-axis representing the sky. The X\({}_{\text{B}}\) axis of the roadheader coordinate system refers to the right side of the roadheader, the Y\({}_{\text{B}}\) axis refers to the forward direction and the Z\({}_{\text{B}}\) axis refers to the upper side. The yaw angle is zero when the Y\({}_{\text{B}}\) axis of the roadheader points north. The heading direction of the tunnel is due west. Figure 17 is the monitoring data of the pose parameters of the excavation roadheader in a certain period of time. The experimental data showed that the roadheader moved westward about 0.7 m at 10:53 and retreated to the starting position at 10:56. This situation is essentially consistent with the on-site feedback. The yaw angle, pitch angle and roll angle of the roadheader have no obvious increase or decrease trend, but the measured data fluctuate within a certain range. Comparing the ground experiments, the fuselage offset error is close to the range of the heading angle error. The analysis results show that the laser navigation system of the roadheader can adapt to the underground working environment and continuously detect the attitude parameters of the roadheader body. Figure 16: The industrial test scenario.