To address the competing relationship between tuber damage and soil removal in potato combine harvesting, this study investigated the operating mechanism of a belt-rod type separator of a small-scale self-propelled potato combine harvester and the separation performance between tuber and soil. The main factors affecting the tuber-soil separation characteristics were derived from a theoretical analysis of the belt-rod angle, belt-rod linear velocity, and harvester forward speed. A simulation model based on DEM (Discrete Element Method)-MBD (Multibody Dynamics) coupling was constructed and single-factor simulation tests were carried out. Then a three-factor, three-level Box–Behnken test was conducted using the coefficient of force on the tuber and soil clearing rate as response indicators. The optimal combination of parameters resulting in low tuber damage and high soil clearing rate was obtained by solving the regression equations. The optimal parameters were a belt-rod angle of 17.5°, a belt-rod linear velocity of 1.37 m/s, and a harvester forward speed of 0.80 m/s. The simulation model was validated by field experiments and the error between the simulation model and the field harvest was found to be 3.81%. The results can be used as a reference for parameter optimization of small-scale potato combine harvesters and coupled DEM-MBD simulation of tuber-soil separation.

This study presents a tangential-axial flow picking device for peanut combine harvesting. The device was designed with reference to the tangential-axial flow threshing mechanism of the grain combine harvesters. The main purpose of this study was to solve the problem of the high rate of loss and damage in the picking operation of the peanut combine harvesters in China. Through the theoretical analysis and design calculation of the key components of the peanut picking device, the structural and working parameters were determined. The orthogonal test was carried out by taking the feeding amount of the peanut plant, the picking clearance, the speed of the tangential cylinder, and the speed of the axial cylinder as the test factors. Additionally, the non-picking loss rate, entrainment loss rate, and damage rate of the peanut pods were used as the test indexes. The test results were analyzed by range analysis and analysis of variance, and the test parameters were optimized by fuzzy comprehensive evaluation method. The optimal parameter combination for the tangential-axial flow picking device was determined as follows. The feeding amount of the peanut plant was 2 kg/s, the picking clearance was 35 mm, the speed of the tangential cylinder was 360 r/min, the speed of the axial cylinder was 425 r/min. At this time, the non-picking loss rate was 0.52%, the entrainment loss rate was 0.54%, and the damage rate was 0.75%. The test results fully met the standard requirements of the peanut picking operation. This research provides a technical basis for the application of the tangential-axial flow picking device in peanut combine harvesters.

Potato is an important food crop in China, and its planting area and output rank first in the world. Due to the labor intensity and low efficiency of manual harvesting, mechanized harvesting has become an inevitable solution for the development of the potato industry. In this paper, on the basis of elaborating on mechanized harvesting operation modes for potatoes, the research progress of key technologies, such as top-killing potato seedlings, low-loss digging with reduced obstruction, limiting the depths of rows, high-efficiency separation, sorting tons of packages, and intelligent harvesting in China and abroad, is analyzed. By comparing the basic structure and technical characteristics of both domestic mechanized potato-harvesting equipment and that used abroad, this paper identifies the gaps between domestic equipment’s performance, intelligence level, and adaptability and those of equipment in European and American countries and also identifies bottlenecks, such as large regional variability, the lack of high-efficiency and low-loss separating devices, and the difficulty of breaking through key “chokepoint” technologies. On this basis, this paper proposes that the future development direction of domestic mechanized potato harvesting should focus on the synergistic development of multiple modes, on the research and development of flexible and low-loss separation equipment, and on the integration of intelligent technology; it also gives specific suggestions, aiming to provide references for the future progress of mechanized potato harvesting.

Peanut is China’s most competitive oil and cash crops internationally. Furthermore, China’s peanut production is the largest in the world. Hence, the peanut industry plays an important role in the national economy. To address the problems of high rates of broken and unharvested pods during peanut harvesting, we researched the dynamic characteristics of harvesting and the mechanisms that influence operation quality. Considering the typical peanut varieties in China’s main peanut-producing areas as the study objects, we studied the mechanical properties of peanut in relation to the harvesting process. By adopting the Box-Behnken design, we set the harvesting net rate Y1, breakage rate Y2, and entrapment loss rate Y3 as the evaluation indices. We performed response surface testing on the peanut-harvesting roller speed, longitudinal size of concave sieve holes, peanut harvesting gap, and feeding volume. Through field verification testing, the parameters for maximum performance were obtained. When the picking roller speed was 260 r/min, the longitudinal dimension of the concave grate sieve pores was 90 mm, the harvesting gap was 40 mm, and the feed rate was 3.3 kg/s. Moreover, the harvesting net rate, breakage rate, and entrapment loss rate were 94.61%, 3.78%, and 0.85%, respectively. Verification testing was carried out based on the optimal parameters, and the results showed that the harvesting net rate, breakage rate, and entrapment loss rate were 95.73%, 3.54%, and 0.84%, respectively. A comprehensive scheme to optimize the peanut harvesting process was proposed to overcome harvesting problems and improve harvest quality. The study conclusions provide theoretical guidance for developing improved tangential-flow peanut-harvesting technology and equipment.

Potato stem removal is one of the critical technical problems of potato mechanized harvesting; it directly affects the quality of potato harvesting and potato storage. There have been several studies on potato stem removal mechanisms. In practice, however, it was found that the potato stem removal rate was greatly influenced by the posture of the stem before it entered the removal mechanism. In this study, we designed a potato stem posture adjustment mechanism consisting of elastic curtains. A test rig was built to investigate the effect of curtain height, curtain width, and curtain suspension height on potato passage rate and potato stem removal rate. The Box–Behnken design (BBD), combined with the response surface method, was used to conduct the test. The optimal construction and installation parameters for each elastic curtain were determined as 278.93 mm for the curtain height, 20 mm for the curtain width, and 260 mm for the curtain suspension height. The predicted values of potato passage rate and potato stem removal rate under the optimal parameters were 92.36% and 82.83%, which were consistent with the validation test results. Based on the optimization results, a rigid-flexible coupled simulation model for a potato stem transported-posture adjustment process based on Abaqus and Adams was constructed. The maximum impact of the elastic curtain of the stem posture adjustment mechanism on the potato stem was 15.91 N and caused the stem to spring back. The projection angle β′ of the stem posture angle in the xoz plane before posture adjustment was 19.07°, and the β′ of the stem after posture adjustment was 87.18°. At this time, the stem was basically parallel to the rod of the separating sieve and had a high probability of falling from the gap of the bar to complete the removal of the stem. Overall, the stem transport position adjustment mechanism effectively adjusted the stem transported posture and improved the stem removal rate in potato mechanical harvesting.

Potato stems removal is an important part of mechanized potato harvesting. However, there is still limited research on the physical properties of potato stems, especially the determination of Poisson’s ratio and Young’s modulus. This study determined the Poisson’s ratio and Young’s modulus of the potato main stems at different heights above the ground. Since the Potato stems are viscoelastic cylinders with non-standard circular cross-sections and complex textures, the existing determination methods are difficult to apply. We propose a new method to determine Poisson’s ratio and Young’s modulus by combining image processing in the mechanical compression process. The feasibility of this method was verified by determining the hardness value of 65 Shore ‘A’ nitrile rubber specimens, and the measured Poisson’s ratio and Young’s modulus were close to the relevant literature. This method can be used for the determination of potato stems. Atlantic potatoes are widely grown for their high solids content, resistance to pests and diseases, and good processing quality. Ten Atlantic potato main stems were randomly selected at harvest time. Specimens with a length of 11 ± 1 mm were taken at 0 cm, 10 cm, 20 cm, and 30 cm above the ground from each stem. The average values of the axial Poisson’s ratio were determined as: 0.21, 0.28, 0.30, 0.32, and the axial Young’s modulus as: 15.90 MPa, 12.38 MPa, 11.68 MPa, 11.28 MPa. This study has provided critical basic data for the discrete element model construction of potato stems and numerical simulation of potato haulm killers and potato harvesters, which is beneficial for improving the harvest quality of potato. It also provides new ideas for Poisson’s ratio and Young’s modulus measurement of non-regular cross-sectional cylindrical viscoelastic materials.