The delivery device is one of the key components in ensuring uniform grain spacing and achieving high-speed precision seeding. In this paper, a new type of high-speed airflow-assisted delivery device for maize is presented. The gas–solid flow in the delivery device was numerically studied by the coupling method of CFD and DEM. The influence of the structural parameters of the delivery device on the movement of the seeds and the airflow field was analyzed in detail. The matching relationship between the inlet-airflow velocity and the operating speed of the seeder was explored. The results show that the position of the intake seed chamber mainly affects the negative pressure in the distribution area of the mixing chamber. The increase in the shrinkage angle results in the decrease in pressure loss and the decrease in airflow velocity in the delivery chamber. As the diffusion angle increases, the airflow forms a stable straight jet flow and the airflow velocity in the delivery chamber increases. As the ejection angle increases, the bouncing degree of the seed decreases, thereby ensuring the consistency of the seed-ejection direction. The research results show that, when the intake seed chamber is located in the middle, the shrinkage angle is 70°, the diffusion angle is 30°, and the exit angle is 60°, the air-assisted delivery device has better performance. With the increase in inlet wind speed, the seed-ejection speed can also be increased according to a certain proportion, which can meet the requirements of zero-speed seeding and ensure the uniformity of seed spacing, providing a new seed delivery scheme. In the future, if invasive damage to the seed shell is guaranteed to be minimized in high-speed airflow, the new delivery device can meet the requirements of precision seeding under high-speed conditions.

Accurate yield estimation before the wheat harvest is very important for precision management, maintaining grain market stability, and ensuring national food security. In this study, to further improve the accuracy of winter wheat yield estimation, machine learning models, including GPR, SVR, and DT, were employed to construct yield estimation models based on the single and multiple growth periods, incorporating the color and multispectral vegetation indexes. The results showed the following: (1) Overall, the performance and accuracy of the yield estimation models based on machine learning were ranked as follows: GPR, SVR, DT. (2) The combination of color indexes and multispectral vegetation indexes effectively improved the yield estimation accuracy of winter wheat compared with the multispectral vegetation indexes and color indexes alone. The accuracy of the yield estimation models based on the multiple growth periods was also higher than that of the single growth period models. The model with multiple growth periods and multiple characteristics had the highest accuracy, with an R² of 0.83, an RMSE of 297.70 kg/hm², and an rRMSE of 4.69%. (3) For the single growth period, the accuracy of the yield estimation models based on the color indexes was lower than that of the yield estimation models based on the multispectral vegetation indexes. For the multiple growth periods, the accuracy of the models constructed by the two types of indexes was very close, with R² of 0.80 and 0.80, RMSE of 330.37 kg/hm² and 328.95 kg/hm², and rRMSE of 5.21% and 5.19%, respectively. This indicates that the low-cost RGB camera has good potential for crop yield estimation. Multi-temporal and multi-sensor remote sensing data fusion can further improve the accuracy of winter wheat yield estimation and provide methods and references for winter wheat yield estimation.

In order to solve the problems of domestic and foreign vegetable precision metering devices that easily damage seeds and have low seeding efficiency and poor qualification rate, this paper designs a one-machine for two-row pneumatic combination seeder, which is mainly composed of a pneumatic seeding mechanism and a honeycomb seeding mechanism. The mechanism and other components and theoretical analysis of the working process of the combined seed metering device clarifies the minimum negative pressure for adsorbing a seed during the suction stage, along with the negative pressure required for the seed-carrying stage. It also establishes the seeding speed and movement during planting with the trajectory parameter equation and uses ADAMS software to conduct virtual experiments on the influence of the number of holes, diameters, and heights of different types of honeycomb seeding disks on the success rate of seeding. Based on research on previous pneumatic seeding mechanisms, single factor tests, orthogonal tests, and high-speed photography tests of the honeycomb seeding disk of the combined seeder were carried out on the number of holes, the diameter of holes, and the height of seeding. The results of tests conducted on okra seeds showed that when the rotating speed of the pneumatic seeding disc was 18 r/min, the diameter of the pneumatic seeding disc hole was 2.4 mm, the vacuum degree was 3.5 kPa, the number of honeycomb seeding disc holes was 24, the hole diameter was 13 mm, and the seed height was 60 mm, the working performance of the combined seed meter reached the optimal level, which provides a reference for the development of a small seed vegetable precision seeder.

Vegetable precision planting agronomy is suitable for my country's current vegetable planting system, and the air-suction vegetable precision planter is currently the most important work tool in my country. This paper designs a kind of air-absorbing vegetable precision sower for the problems of small vegetable seeds with small grains, poor mobility and high difficulty in achieving uniform sowing of small seeds. First, Fluent software is used to simulate and analyze the flow field of the air chamber in the seed metering device, and the pressure and velocity of the fluid in the air chamber are analyzed. Through the comparison of the pressure distribution cloud chart and the velocity distribution cloud chart, the influence of different apertures, holes, vacuum degree, and gas chamber depth on the flow field of the gas chamber is analyzed. The air suction seed discharger test bench was set up and orthogonal test was carried out, and the test results showed that the optimal parameter combination was 3.5 kPa vacuum degree of the air chamber, 2.4 mm diameter of the type hole, and 18 r/min rotational speed of the seed discharging disk. The high-speed photographic test was carried out under the optimal parameter combination, and the results showed that leakage of suction, adsorption of 1 seed, and adsorption of multiple seeds appeared in the process of suction, and it is important for the development of the air suction precision machine for small seeded vegetables with better performance. The results showed that the phenomenon of leakage, adsorption of 1 seed and adsorption of multiple seeds occurred in the process of seed suction, which provided a reference basis for the development of a better performance of the air-absorption precision planter for small seeds.

In order to elucidate the impact of pressurized tubes’ structures on the sowing performance of pneumatic seed delivery systems, the EDEM–CFD coupled simulation method was employed to analyze the influence of pressurized tube parameters, including length (L), corrugation depth (S), corrugation width (K), and the number of corrugations, on seed movement characteristics, distribution uniformity, and airflow patterns. Simulation-validated experiments were conducted to study the impact of the optimal pressurized tube structure on seeding performance. The results indicate that pressurized tubes significantly enhance the uniformity coefficient of seed distribution, reduce seed velocity, and decrease the coefficient of variation in distribution uniformity. When pressurized tube parameters, specifically length (L), corrugation depth (S), corrugation width (K), and the number of corrugations, are set at 800 mm, 8 mm, 50 mm, and 6, respectively, the uniformity coefficient of seed distribution exceeds 95%, and the coefficient of variation in seed discharge consistency for each row is less than 3.2%. Moreover, the seed velocity at the outlet of the pressurized tube, the relative velocity of two-phase flow, and pressure loss are all minimal, indicating superior seeding performance. This research provides valuable insights into the analysis of seed movement characteristics within pressurized tubes and the optimization of their structural parameters.

To solve the problem of grain loss caused by nibbling during the working process of the maize ear and stem harvesting machine, a vibrating screen-type grain-recovery device with an upper centrifugal fan was designed. The device mainly consists of a centrifugal fan and vibrating screen. The work process of the grain-recovery device is theoretically analyzed, and it is clarified that the turning of the bracts is the key to separating the bracts from the grains, and the design criteria of the vibrating screen are obtained. The CFD–EDEM coupled single-factor simulation experiment was carried out on the size of the vibrating screen sieve hole and the number of draft bars, and the motion posture of the bracts was simulated. Based on the previous CFD–EDEM coupled simulation study, the orthogonal experiment was carried out on the fan speed, vibration screen drive-shaft speed, and operation speed of the grain-recovery device. The orthogonal experimental results show that, when the fan speed is 1000 r/min, the vibration screen drive-shaft speed is 300 r/min, and the operation speed is 3.62 km/h, the performance of the grain-recovery device reaches the optimum level, and the grain recovery rate is approximately 85%.