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.

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.