## 2 Materials and Methods  
### Structure and Working Principle of the Weeder  
The inter row weeding device is mounted on a self-propelled power platform to form a paddy field self-propelled inter row weeder. The structure of the weeder is a connecting rod, a frame, crawlers, supporting wheels, suspension frames, driving wheels, an inter row weeding device, electric control equipment and a visual recognition system. The driving wheels, supporting wheels and crawlers constitute the walking system, which effectively increases the contact area with the field soil to prevent subsidence and realizes flexible steering based on the difference in the speeds of the driving wheels. The visual recognition system can effectively monitor the position of the seedling belt and ensure that the straight line runs between the lines. The inter row weeding device is mounted on the rear connecting rod of the machine, which allows the weeding spacing and height to be adjusted according to the agronomic requirements of rice planting in different regions, and it has good adaptability. The structure of the weeder is shown in Figure 1, and the technical parameters are shown in Table 1.  
When the machine is working, the visual recognition system extracts the surrounding environment information in real time and identifies the rice seedling belt through distortion correction, feature extraction, image noise reduction, and seedling belt fitting. After the image information is processed by the host computer, the deviation signal is transmitted to the electronic control equipment. The driving wheels transmitted through the planetary gear reducer decelerate to increase torque. When the driving force of the crawler is greater than the resistance of the weeder, the supporting wheels rotate in the crawler to complete the vision recognition of the seedling belt and inter row walking. The weeds are buried in the soil by disturbing and compacting the soil by driving the weeding wheels with rake teeth. The operational status is shown in Figure 2.  
The inter row weeding devices are mainly composed of motor box covers, side transmission boxes, upper sprockets, planetary gear reducers, brushless DC motors, motor  
\begin{table}
\begin{tabular}{c c} \hline \hline
**Parameters** & **Value** \\ \hline Dimensions (length, width and height)/mm & 650 \(\times\) 500 \(\times\) 386 \\ Lowest ground clearance of the chassis/mm & 240 \\ Mass (Counterweight)/kg & 80 \\ Rated power of the whole machine/kW & 1.6 \\ Chassis rated torque/(N\(\cdot\)m) & 32 \\ Rated torque of the weeding device/(N\(\cdot\)m) & 19 \\ Width of the crawler/mm & 80 \\ Width of the weeding wheels/mm & 170 \\ Path planning & Visual recognition system \\ Form of the weeding wheels & Driving weeding wheels with rake teeth \\ \hline \hline \end{tabular}
\end{table}
Table 1: Main technical parameters of a paddy field self-propelled inter row weeder.  
Figure 1: Paddy field self-propelled inter row weeder: (1) connecting rod, (2) frame, (3) crawler, (4) supporting wheel, (5) Suspension Frame, (6) driving wheel, (7) rear connecting frame, (8) inter row weeding device, (9) electric control equipment, (10) visual recognition system.  
Figure 2: Working status of the paddy field self-propelled inter row weeder.  
boxes, connecting plates, weeding wheels, lower sprockets, weeding wheel axles, chains, a bearing pedestal and weeding wheel frames. The overall structure is shown in Figure 3. The power of the device is provided by the motor, which is fixed on the chassis frame by bolts. By adjusting the position of the connecting plates on the left, right, top and bottom of the chassis, the row spacing and depth of weeding can be changed to meet and adapt to the operational requirements for different row spacing sizes and land conditions. Lateral transmission is realized by the upper sprocket, lower sprocket and chain.