## 1 Introduction  
Weeds occupy a large proportion of the agricultural paddy ecosystem and compete with rice for growth space, fertilizer, nutrients, light, water and heat resources, resulting in a decline in rice yield and quality, which has a direct effect on national food security and productivity [1, 2, 3]. According to data analysis, the annual loss of rice yield caused by weeds was approximately 15% [4]. Chemical spraying is the main traditional weeding method, but this approach leads to pesticide residue, soil hardening and other problems, which is not conducive to the sustainable development of agricultural production [5]. In recent years, mechanical weeding has become a key measure for the production of organic rice because of its advantages of not polluting the environment, increasing soil aeration, and improving the soil temperature. Mechanical weeding has become the main method to improve the quality of rice and ensure the safety of rice [6].  
The environmental conditions of paddy fields are complex. In Europe and America, most rice sowing is broadcast, and rice seedlings grow in a disorderly manner. The weeder cannot work in paddy fields, and most weeding is performed with chemical pesticides [7; 8]. In Asia, rice planting is mainly performed via mechanical transplanting, and the seedlings grow orderly, which can be beneficial for developing sustainable mechanical weeding technology [9]. Among them, the advanced representative weeders are Japan's MJJ-4 and Meishan SMW [10; 11]. The inter row weeding component is a driven weeding roller, which has poor adaptability in different planting patterns and complex paddy field environments, and effective weeding cannot be guaranteed. Research on weeders in paddy fields began relatively late in China, and there are few molding machines, which are in the stage of theoretical research and experimental testing and have not been popularized and applied [12]. The representative machines mainly include the 3 ZS-150 stepping weeder designed by [PERSON] of Northeast Agricultural University [13] and the 3 GY-1920 paddy field weeder designed by [PERSON] of South China Agricultural University [14], 3 GY-1920 weeder was equipped with spiral knife tooth weeding structure, which was integrally equipped with multiple rows of weeding parts; however, the weeding rate cannot be guaranteed, so the machines needed to be driven manually. At present, most of the weeders developed in China are stepping weeders [15], although the rate of weeding is guaranteed, manual operation is needed to operate the machine, which is not only inefficient and labor intensity is high but also compacts the soil due to secondary trampling compaction. In addition, [PERSON]'s team at Northeast Agricultural University developed a self-propelled inter row weeder for applications in paddy field environments based on visual recognition [16]. This weeder is suitable for the high standard associated with paddy field planting in Northeast China, but there are still disadvantages, such as the need to improve the operation quality of inter row weeding components, the lack of an obvious tillage effect, and other problems.  
In view of the above problems, this research takes the paddy field self-propelled inter row weeder developed by the team as the research subject. The main factors affecting the weeding effect were explored through the theoretical analysis of the weeder based on burying weeding. The structure of the rake teeth weeding wheel was designed and matched with appropriate power, and the rake teeth weeding device was optimized. The field optimization experiment was carried out by a quadratic orthogonal rotation combination design with three factors and five levels. To intuitively analyze the soil disturbance of the weeding wheel, a fluid-solid coupling simulation model of the weeding wheel and water soil was established. The study provides a theoretical basis and simulation references for weeding equipment in paddy fields.