## 1 Introduction  
With the development of technologies such as global positioning systems, remote sensing, sensors, and geographic information systems, agricultural production demands higher-precision seeding technology to improve the quality of seeding operations and reduce the cost of machine operations [1; 2; 3]. In the 1940s, relevant foreign scholars began to study precision seeding technology. This technology is a critical technological innovation in modern agriculture through which seed spacing, row spacing, sowing depth, and density can be accurately controlled. This not only saves time and seeds and improves the quality of operations but also maximizes the productivity and quality of crops and reduces the waste of resources [4; 5]. The final position of the seed under precision sowing is mainly the result of the combined work of certain components, such as the profiling device, the furrowing device, the seeding device, and the soil covering and compacting device. Any one of these affects the seed distribution in the soil, which in turn affects the seeding quality. Sowing depth is a critical evaluation index of sowing quality, which is closely related to the soil condition and temperature level around the seed, and the sowing depth will directly affect the germination growth and development of the seed [6; 7; 8]. When the sowing depth is shallow, the water needed for crop growth is insufficient due to the limited water in the surface layer of the soil, and it is not easy to achieve the conditions needed for seed germination. When the sowing depth is deep, the water in the deep soil layer can meet the conditions for seed germination. However, it is difficult for the seeds to get enough oxygen, and it is difficult for the seeds to emerge from the soil after germination [9]. Inconsistency in sowing depths can result in seedling shortages (e.g., small seedlings), and reduced crop yields (Figure 1; Supplementary Table S1) [10; 11]. [PERSON] et al. tested maize emergence at different sowing depths and found that maize emergence was best at 60 mm sowing depth [12]. [PERSON] et al. used a planter equipped with a passive downforce spring testing three different sowing depths and different downforce. They found that the planter failed to make sowing depths across the field uniform at the same downforce and predefined sowing depth, with a maximum sowing depth difference of 2.1 cm. This study also found that climatic conditions at different sowing depths and downforce affected maize emergence and yield. The lower temperature and the shallower sowing depth led to higher emergence [13; 14]. In addition to seeding depth, downforce is also one of the important evaluation indexes of seeding quality [15]. Appropriate downforce ensures the seeds are in close contact with the soil and promotes germination and growth. Higher downforce may result in the seed being pressed tightly against the soil, affecting its germination quality. Smaller downforce may result in the seeds being not fully in contact with the soil [16; 17]. [PERSON] et al. studied the growth of maize under different depth-limiting wheel pressures and found that the growth of maize plants is affected by the pressure under the depth-limiting wheel and soil moisture. Therefore, appropriate sowing depth and downforce are essential for seed emergence, maximizing competition among seedlings, improving seedling neatness, and increasing crop yields [18; 19]. From the above studies, it is clear that proper seeding depth and downforce play an important role in increasing the yield of the crop. The profiling adjustment device mainly determines the downforce, and the downforce adjustment is an essential factor affecting the stability of the furrowing depth of the planter. Furrowing depth stability is the main factor affecting seeding depth [20].