The primary objective of this study was to address the challenges associated with the harvesting of ginger, namely the large resistance to digging, the high damage rate, and the high impurity rate of the harvested ginger. To this end, a digging-shaking-pulling ginger harvesting device (DSPGHD) was designed and optimized. The device was then analyzed in accordance with agronomic requirements for ginger planting and harvesting. This analysis involved the examination of interactions between ginger, soil, and mechanisms at each stage of the harvesting process. The study determined the key factors affecting the harvesting indices, including the initial angle of the clearing bar (IACB) φ, the length of the clearing bar (LCB) l₂, and the frequency of shaking (FS) f. The coupled EDEM-RecurDyn simulation system was established, and the key factors were tested with the forward resistance, the ginger force, and the effect of the soil flow as the test indices. A single-factor test was conducted, and the test result data was analyzed to determine the factor influence law. The field orthogonal test was then designed to optimize the parameter combinations of the device, and the response surface analysis and multi-objective optimization method were used to obtain better parameter combinations of the evaluation indices of ginger harvesting. These were as follows: the IACB was 8.7°, the LCB was 256 mm, and the FS was 4.24 Hz. The sizes of the test indices were as follows: the forward resistance was 1526 N, the damage rate was 4.57%, and the impurity rate was 3.74%. The DEM-MBD model developed in this study has the capacity to investigate the interactions between the primary factors of the DSPGHD and ginger-soil. It can optimize the geometric structure of the machine and provide a theoretical foundation for field trials. The optimized results from the field orthogonal test can satisfy the agronomic requirements and use requirements of ginger harvesting, and reduce the input of labor.

The objective of this research was to enhance the stability and consistency of seed distribution during carrot planting. The impact of the seed guide tube’s structure on seeding quality was examined, leading to the design of a cycloidal seed guide system augmented by positive pressure airflow. By conducting kinematic modeling of the collision position of the seeds within the seed guiding system, as well as considering the seed guiding process and the seed drop position, the significant parameters influencing the final velocity of the seeds were determined. Employing a coupled Discrete Element Method-Computational Fluid Dynamics (DEM-CFD) simulation, the effects of different structural and operating parameters of the seed guide tube on the seed trajectory and airflow field were analyzed. A three-factor five-level orthogonal test was then utilized to examine the influence of each factor on each index, with the optimal conditions identified as an inlet airflow velocity of 0.077 m/s, a 45° tilt angle for the airflow branch tube, and a seed initial velocity of 0.1 m/s. Under these parameters, the qualification index was recorded as 94.1%, with a coefficient of variation of 3.2%. Bench testing conducted under the same conditions showed a decrease of 0.07% in the qualification index, and an increase of 1.875% in the coefficient of variation, with errors relative to the simulation results within acceptable bounds. These findings enhance the stability and reliability of the seed guiding system during carrot sowing operations, aligning with the demands of precision sowing.

A scallion is one of the most favorite vegetables in the world. However, manual and semi-mechanized operations cannot fully meet the large-scale harvesting of the scallion industry in recent years. Some challenges also remained in mechanized scallion harvesting, such as soil clogging and crop damage. This study aims to present the design, key component optimization, and field validation of the 4 LQ-1 side traction scallion combine harvester. Five subsystems were integrated in the harvester: a depth-limited device, a combined excavation device, a conveying and soil-cleaning device, a lateral laying device, and a transmission system. The sequential operations were then realized, including the ridge-side soil separation, excavation and lifting, clamping and conveying, rotary soil cleaning, and lateral laying in a single pass. Technical parameters included an overall dimension of 3 600×2 100×1 400 mm (length×width×height), a matched power of no less than 88.2 kW, a working width of 0.25 m, a total weight of 436 kg, a three-point hitch connection, and a working speed range of 0.3-0.4 m/s. One key part of the harvester, the combined excavation device consisted of a soil separation and an excavation-lifting mechanism: The soil separation mechanism was used the rotating spiral blades (with the maximum diameter of 250 mm and a shaft diameter of 75 mm) to cut, crush, and push soil from both sides of the scallion ridge, thus reducing the soil volume that handled by the excavation shovel, in order to prevent the soil clogging; The excavation-lifting mechanism was adopted a trapezoidal digging shovel (275 mm in width and 120 mm in length) to minimize the excavation resistance, paired with lifting bars (250 mm in length and 75 mm in spacing) that loosen and lift the soil-scallion mixture, thus allowing crushed soil to fall through the bar gaps during lifting. The conveying and soil-cleaning device comprised a clamping and conveying mechanism, as well as a rotary soil-cleaning mechanism: The clamping mechanism was used the flexible foam rubber belts (100 mm in width) to gently grip the scallion at the junction of leaves and the white part (scallion bulb), with a feeding inlet width of 300 mm (matching the average leaf spread of mature scallions) and a depth of 600 mm, in order to obtain the stable clamping without damaging the crop; The rotary soil-cleaning mechanism was employed the rubber rods rotating at 20 r/s to strike and remove adhering soil from scallion roots, thus balancing the cleaning efficiency and crop protection (in order to avoid the damage caused by excessive rotation speed). The transmission system was used to draw the power from a tractor: the tractor’s power take-off shaft was connected to the harvester’s main drive shaft via a universal joint and an HD input commutator, thus powering the soil separation mechanism (through an HD output commutator and chain drive) and the rotary soil-cleaning mechanism (through chain drive). The tractor’s hydraulic system was used to drive the clamping belt’s hydraulic motor and lifting cylinders. The lateral laying device was powered by the harvester’s own electrical system. A three-factor and three-level orthogonal experiment was conducted to optimize the performance. The variables were taken as the forward speed, soil separation mechanism rotation speed, and clamping belt inclination angle. While the evaluation indicators were taken as the leakage rate (unharvested scallions), damage rate (structurally damaged scallions), and excavation rate (successfully harvested scallions). The experiment was carried out in a sandy loam field in Jiaozhou, Shandong Province, China, in May 2024. The soil moisture content was 8.3%, soil compaction was 0.6 MPa, and scallions were planted with 269 mm ridge height, 801 mm ridge spacing, and 62 mm plant spacing. Mathematical models between factors and indicators were established using Design-Expert software. The optimal combination of the parameters was determined: a forward speed of 300 mm/s, a soil separation mechanism rotation speed of 200 r/min, and a clamping belt inclination angle of 30°. Field validation tests (three replicates, each covering 100 m of ridge) showed that the leakage rate was 0.8%, the damage rate was 2.85%, and the excavation rate was 98.7% under the optimal parameters. The absolute error between the measured and model predictions was within 5%, fully meeting the technical requirements for the scallion harvesting equipment. This finding can provide the theoretical basis and technical support to the structural and performance enhancement of the side traction scallion harvesters, and effectively reduce the harvesting costs for the high operation quality of the ridge-planted scallions.

In order to establish an accurate discrete element model of alfalfa seeds, real physical experiments were combined with simulation experiments, and the contact parameters of alfalfa seeds were calibrated using the repose angle of alfalfa seeds as the response value. Some intrinsic parameters (thousand grain weight, triaxial size, density) and contact parameters (static friction coefficient, rolling friction coefficient) of alfalfa seeds were obtained through physical experiments, and a spherical particle model was established. Through the Plackett Burman experiment, the static friction coefficient between alfalfa seeds, the rolling friction coefficient between alfalfa seeds, and the static friction coefficient between alfalfa seeds and ABS plastic were determined to have a significant impact on the experiment. The steepest climb test is used to narrow down the selection range of the optimal parameters, and the box Behnken test is used to obtain the quadratic regression equation of the repose angle. The optimal parameter combination was obtained with the objective of minimizing the repose angle error: the static friction coefficient between alfalfa seeds and alfalfa seeds was 0.418, the rolling friction coefficient between alfalfa seeds and alfalfa seeds was 0.086, and the static friction coefficient between alfalfa seeds and ABS plastic was 0.471. The repose angle and mass flow rate experiments show that the model is effective and reliable.

In order to systematically obtain the excavation characteristic parameters for ginger harvesting, experimental analysis was conducted on the discrete elemental parameters in a particle simulation model of the ginger-soil system. Through stacking tests, the surface energy of soil-ginger tuber JKR was determined to be 3.7 J/m², the coefficient of static friction of soil-steel (65 Mn) was 0.56, the coefficient of rolling friction was 0.03, and the coefficient of restitution of collision was 0.40. Utilizing normal and lateral compression tests conducted on the soil body, the soil base parameters required for the Bonding model were determined. Subsequently, a three-dimensional model of ginger root and stem was constructed using these parameters. With the aid of 3D scanning technology, a discrete element parameter model was established for the ginger field during the harvesting period. On the basis of the measured parameters, a three-dimensional model of ginger rhizome was established and finally a discrete parameter model of ginger field was constructed in the harvesting period. The calibration parameters are highly reliable after the model’s tightness and field harvesting test, which provides reliable data support for the soil flow and the force of the soil-touching parts during the later simulation of ginger harvesting and digging operation.

In green onion harvesting, the problems of easy dumping and low rate of clean digging can be encountered. In this paper, a kind of harvesting device for digging and pulling green onions, referred to simply as "the device", was designed. The device mainly consists of a digging shovel, screen bars, clamping conveyor belt, etc. This paper focuses on the analysis of the model forces of green onions and soil in the two states of the onion digging process without dumping and clamping. The key factors affecting the model state of onions and soil were identified as: screen bar length l₂, screen bar inclination angle β, and pulling point position x. Based on the discrete element simulation technology of EDEM, the mechanism-crop-soil model was established, and a single-factor simulation test was conducted to determine the range of values for each factor. Taking the advantages of field test and three-factor five-level orthogonal experimental design, the parameter combinations of green onion harvesting operation evaluation indices were optimized, including a pulling point position of 166 mm, screen bar length of 242 mm, and screen bar inclination angle of 14°. As the results of the field test show, the harvester operation was stable without congestion or damage, the harvesting effect of green onions was improved, and the clean digging rate reached 100%, which meets the agronomic requirements for onion harvesting and the expectations of users.