## 3 Multi-Sensor-Based Remote Autonomous Navigation and Close-Range
### Proximity Docking Localization Based on Infrared Sensors  
After completing the remote autonomous navigation, proximity docking and charging are carried out using infrared sensors. The infrared emitter used has a wavelength of 940 nm and a low emission power. It starts emitting infrared rays as soon as the power is turned on, with a detection range of approximately 1.5-3 m. The infrared receiver is an HS0038 pulse-type receiver, which outputs a low level when receiving a modulated 38 kHz infrared carrier, and a high level otherwise. The charging station controls the left and right infrared emitters to emit 38 kHz infrared carriers for different durations, as shown in Figure 7. The carrier duration for emitter A is 39 ms, and for emitter B it is 52 ms. Emitters A and B alternate their infrared signals. The automatic recharging system identifies the different regions A or B based on the carrier duration of the emitted infrared signal. When the robot is in the infrared signal region A, only receiver R receives the A signal while receiver L does not receive the infrared signal. This indicates that the charging station is located to the robot's right front. The robot can then be controlled to turn right or move forward towards the right. With the correct procedural logic control, the robot will eventually align with the charging station and complete the docking. The infrared docking control logic is shown in Table 2, where positive values are used for forward movement and counterclockwise rotation. Figure 7: Infrared signal timing diagram. When the robot aligns with the charging station and the charging ports make contact, an electrical circuit is formed and charging begins. When the robot is directly facing the charging station, [PERSON] will necessarily receive the infrared signal A and R will receive the infrared signal B. The schematic of the infrared docking process is shown in Figure 8.  
As the robot autonomously navigates close to the charging station, the infrared reception status of L or R will change, as shown in the figures. If L receives both infrared signals A and B and R does not receive any infrared signal, according to Table 2, the robot should turn counterclockwise. The robot will continue to rotate counterclockwise until the infrared reception status of L or R changes. If L receives both infrared signals A and B and R only receives infrared signal B, according to Table 2, the robot should continue to turn counterclockwise. The robot will keep rotating counterclockwise until the infrared reception status of both L and R changes, with L only receiving infrared signal A and R only receiving infrared signal B. According to Table 2, the robot should then move backward. The robot will move backward until the infrared reception status of L or R changes. If L receives both infrared signals A and B and R receives infrared signal B, according to Table 2, the robot should turn counterclockwise again. The subsequent movement of the robot will be a cycle of counterclockwise rotation and backward movement until it is perfectly aligned with the charging station. At this point, the robot will continue moving forward to complete the docking and start charging. \begin{table}
\begin{tabular}{c c c c c c c c c c} \hline \hline
**Position** & **Sensor** & **S1** & **S2** & **S3** & **S4** & **S5** & **S6** & **S7** & **S8** \\ \hline \multirow{2}{*}{L} & A & 1 & 1 & 1 & 1 & 1 & 1 & 1 & 1 \\  & B & 1 & 1 & 1 & 1 & 0 & 0 & 0 & 0 \\ \hline \multirow{2}{*}{R} & A & 1 & 1 & 0 & 0 & 1 & 1 & 0 & 0 \\  & B & 1 & 0 & 1 & 0 & 1 & 0 & 1 & 0 \\ \hline Control Action & Back & / & Reverse & Reverse & Forward & Forward & Back & Back \\ \hline \multirow{2}{*}{\(X\)-axis (m/s)} & \(-\)0.1 & / & 0 & 0 & 0 & \(-\)0.1 & \(-\)0.1 & \(-\)0.1 \\ \hline \multirow{2}{*}{\(Z\)-axis (rad/s)} & 0 & / & 0.1 & 0.1 & \(-\)0.1 & \(-\)0.1 & 0 & 0 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: The infrared docking control logic. Figure 8: Infrared docking process showing the stages from approach to successful docking.