In view of the problems of the inability to continuously adjust the seeding rate, small adjustment range, and low precision of the rice direct seed-metering device, a variable capacity roller-wheel seed-metering device was designed, fabricated, and verified. With the variable capacity method, the seeding rate could be adjusted steplessly and with high precision through the seeding rate adjusting mechanism. Meanwhile, theoretical analysis and parametric design of the critical components, such as the seeding wheel and the seeding rate adjusting mechanism, were carried out. The rotation speed of the seed-metering device, the sphericity of rice seeds, and the adjustment depth were selected as the main influencing factors of the experiment. Then, the full-factor experiment was conducted, and the results of the bench validation experiments showed that the average seeds per hill error of the seed-metering device could be controlled within 2%. Meanwhile, the seed-metering device performed the best when the rotation speed of the seed meter device was 30 r/min, the sphericity of rice seeds was 52.7%, and the hole depth was 6 mm. Compared to the conventional mechanical precision seed-metering device, the designed seed-metering device offered better seeding performance. The research results provide theoretical and practical references for the design of a rice seed-metering device and the development of precision agriculture.

To improve the expandability, seeding accuracy, and operating speed range of the electric drive system (EDS) of precision seeders, this study constructed an EDS based on a controller area network (CAN) bus and designed a motor controller based on a field-orientated control (FOC) algorithm. Full-factorial bench and field tests based on seed spacing (0.1, 0.2, and 0.3 m) and operating speed (3, 6, 9, 12, and 15 km/h) were carried out to evaluate the performance of the EDS. The results of bench tests showed that seeding quality varied inversely with operating speed and positively with seed spacing. The average quality of feed index (QFI) at 0.1, 0.2, and 0.3 m seed spacing in bench tests was 88.38%, 96.67%, and 97.36%, with the average coefficient of variation (CV) being 20.13%, 16.27%, and 13.20%. Analysis of variance confirmed that both operating speed and seed spacing had a significant effect on QFI and CV (p < 0.001). The analysis of motor rotational speed accuracy showed that the relative error of motor rotational speed above 410 rpm did not exceed 2.24%, and the relative error had less influence on the seeding quality. The average QFI was 85.93%, 95.91%, and 96.24%, with the average CV being 21.12%, 15.50%, and 16.49% at 0.1, 0.2, and 0.3 m seed spacing in field tests. The methods and results of this study can provide a reference for the design and optimization of the EDS in a maize precision seeder and provide an effective solution for the improvement of maize yields.

The yield and quality of sweet potatoes are significantly influenced by the transplantation posture of sweet potato seedlings. The performance of the sweet potato seedling transplanting opener directly affects the transplantation posture of sweet potato seedlings. In order to improve the yield and quality of sweet potatoes, this study proposes a joint simulation method based on discrete element and flexible multi body dynamics (DEM-FMBD), which optimizes the structure of a self-covering soil opener. By exploring the influence of self-covering soil trenchers on the planting depth and posture of sweet potato seedlings during horizontal transplantation, it was determined that the influencing factors of the experiment were wing spacing, soil reflux height, and soil reflux length. Based on the DEM-FMBD coupling simulation platform, single factor, and quadratic rotation orthogonal experiments were carried out. According to the results of the simulation test, the effect of the interaction of test factors on planting depth and planting attitude was analyzed by the response surface method. Finally, the optimal structural parameter combination was obtained by a multi-objective optimization method: the spacing of the wings was 58 mm, the height of the soil backflow port was 71 mm, and the length of the soil backflow port was 163 mm; thus, the quality of transplanting is improved effectively. This study provides the method and theory reference for the study of sweet potato transplanting.

Introduction: To improve the mechanization level of rice planting, a new type of direct seeding device for rice was designed. The device's structural properties will be crucial in determining its seeding performance. Structure optimization in the current seed metering device design process focuses on a single or few indexes, resulting in improved individual performance but imbalanced overall performance. Therefore, a structure optimization method of the direct seeding device based on a multi-index orthogonal experiment was proposed in this study.Methods: First, the DEM-MBD coupling method observed the factors and levels that affected the performance overall. Second, a test platform based on the electric drive control model was constructed, and a multi-index orthogonal test was devised. Finally, the structural parameters of the seed metering devices were optimized based on matrix analysis.Results: From the results, the primary and secondary levels of significance of factors were just as follows: hole diameter > hole number > adjustment angle. The following are the optimal parameters found by optimization analysis: the diameter of the hole was 12 mm, the number of holes was 10, and the adjustment angle was 80°. Validation tests were carried out and analyzed based on the optimal structural parameter combination. The qualification rate of seeds per hole, empty hole rate, average seed number, coefficient of variation of seed number, average hole spacing, and the variance coefficient of hole spacing are 93.07%, 0%, 9.39,14.04%, 22.84 cm, and 9.14%, respectively.Discussion: In comparison to traditional design and structural parameter optimization methods for rice precision seed metering device, this study not just to provides an optimization scheme for improving the overall performance of rice precision seed metering device, but also serves as a technical reference for the development and design of new rice precision seed metering device.

This study develops a novel electric-driven metering device to address the mismatch between the seeder rotation speed and vehicle speed in traditional mechanical precision hill direct-seeding metering devices for rice, which is caused by wheel slippage. The device integrates a Global Navigation Satellite System (GNSS) speed measurement module and an optimised incremental Proportional-Integral-Derivative (PID) control algorithm, enabling precise seeding through electric drive. A multidisciplinary collaborative design approach is employed, and field experiments are conducted to evaluate the performance of the novel device under conditions of vehicle speeds ranging from 3 to 5 km/h, theoretical hill spacings of 0.15–0.25 m, and seeding rate adjustment positions of 1/3–1. The experiments use two rice varieties, “Longken 2021” from the northern rice growing region and “Jingliangyou Huazhan” from the southern rice growing region. The results demonstrate that the novel electric-driven metering device significantly outperformed the traditional mechanical device in terms of seeding precision, hill formation performance, and seeding rate accuracy. The novel device achieves a qualified rate of seeds per hill of 90.54%, with seedling omission and seed damage rates reduced to 4.98% and 0.69%, respectively. The hill diameter qualification rate increases to 95.21%, with no empty hills observed. The coefficient of variation of seeds per hill is maintained at 21.98%, meeting the agronomic requirement of 2–12 seeds per hill for conventional rice. However, for seeds with high moisture content and poor flowability (soaked seeds), the seed damage rate increases slightly by 0.47 percentage points. This study provided an efficient and reliable technical solution for the intelligent upgrading of precision rice direct-seeding equipment.

This study proposes a positive pressure re-acceleration assisted seeding mechanism and analyzes the motion mechanism of corn seeds during the seeding process. By employing the CFD-EDEM gas-solid coupling simulation analysis method, the fluid characteristics, initial ejection velocity of seeds, seed dropping time difference, and sowing position difference in the seeding mechanism under different structural parameters of the air pressure valve body were investigated. The optimal structural parameters of the air pressure valve body were determined (nozzle gap c = 0.6 mm, throat constriction diameter d = 16 mm, and throat constriction length l = 44 mm). A multi-factor experimental method was used to explore the effects of airflow pressure, forward speed during sowing, and sowing distance on sowing performance, aiming to identify the optimal working parameters for the positive pressure re-acceleration seeding mechanism. High-speed camera technology was used to record and analyze the seed movement process. The results indicate that an increase in positive pressure within the seed guide tube shortens the sowing time of corn seeds, reduces the coefficient of variation of seed dropping time difference, and effectively improves the consistency of sowing distance. The optimal parameters are a forward speed of 8 km/h, sowing distance of 20 cm, airflow pressure of 10 kPa, with a sowing distance coefficient of variation of 7.56%, and a seed dropping time difference coefficient of variation of 5.35%.