## 2 Multi-Sensor Fusion-Based Autonomous Recharging System for AGVs  
### Hardware Components of the Multi-Sensor Fusion-Based Autonomous Recharging System  
The multi-sensor fusion-based autonomous recharging system for unmanned vehicles consists of several key components: LiDAR, cameras, infrared sensors, the control system, and the charging station. The LiDAR is used for environmental scanning and mapping, generating a high-precision map by real-time perception of the surrounding environment. This map is then combined with the visual information captured by the camera to achieve long-range navigation and obstacle avoidance. The camera provides additional environmental perception data, supplementing the blind spots of the LiDAR. When the unmanned vehicle approaches the charging station, the infrared sensor becomes crucial. Infrared transmitters installed on the charging station emit multiple infrared signal areas, which are received by the infrared receivers on the vehicle. These signals help determine the vehicle'srelative position and orientation with respect to the charging station, enabling precise docking. The control system integrates data from the LiDAR, camera, and infrared sensors and, through multi-sensor fusion algorithms, continuously calculates the vehicle's position and path planning to ensure that the vehicle can accurately locate the charging station and complete the autonomous recharging process. The system diagram of the autonomous recharging system is shown in Figure 1.  
The infrared docking part is a crucial component of the autonomous charging system for the unmanned vehicle, with the hardware mainly comprising infrared transmitting tubes and infrared receiving tubes. Two or more infrared transmitting tubes are installed on the charging station, which create multiple infrared signal zones centered around the charging station. The unmanned vehicle is equipped with two or more infrared receiving tubes that detect these infrared signals to determine the vehicle's position within the signal zones and its relative orientation to the charging station. By processing and analyzing the received signals, the vehicle can accurately adjust its position and orientation to achieve precise docking with the charging station.  
On the charging station, two infrared transmitting tubes (A and B) are installed, and a partition is added between them, splitting the infrared signals into two zones centered on the charging station (A and B zones). As shown in Figure 2, the robot positioning relative to the charging station varies between side (Figure 2a) and front views (Figure 2b). The vehicle's front side is equipped with two infrared receiving heads (L for Left and R for Right), with a partition added between them, dividing the vehicle's receiving area into two zones as well. By determining which infrared signals are received by the L and R infrared receiving tubes, the vehicle can ascertain the orientation of the charging station relative to the vehicle and the directional deviation between the vehicle's front and the front of the charging station.  
Figure 1: Hardware components of the multi-sensor fusion-based autonomous recharging system.  
Figure 2: Robot positioning relative to the charging station: side vs. front view.