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The existing oil sunflower threshing device cannot meet the requirements of oil sunflower threshing under different conditions. Aiming at the problems of the low oil sunflower threshing rate and the high breaking rate during the threshing process, a threshing device of oil sunflower with variable clearance based on multi-bar mechanism is designed in this paper. The structure and the working principle of the oil-sunflower threshing device with variable clearance were introduced, and the mechanisms of kinematics of the clearance adjustment mechanism and angle adjustment mechanism of the structure of variable clearance concave screen were analyzed, the motion trajectory analysis and solution were performed to determine the structural parameters, the variable clearance range of the variable clearance concave sieve was 20-60 mm. A test bench of the oil-sunflower threshing device with variable clearance was developed. The threshing test was completed at the Key Laboratory of Innovation Design Laboratory of Xinjiang Agricultural Engineering Equipment. The test object was oil sunflower No. 31 with the disk diameter of 180-220 mm and the disk thickness of 25-40 mm, the weight of single sunflower disk was 300-380 g, the moisture content of the sunflower disk was 29.59%. The test was performed according to the GB/T5982-2017 thresher test method and the DB37/T2878.2-2016 technical requirements. The orthogonal experiment of three factors and three levels was carried out, threshing rate and breaking rate were taken as the indexes and the cylinder speed，the threshing clearance as well as feed rate were the factors. The test results showed that during the threshing process, the factors that affect the oil sunflower threshing rate and breaking rate are threshing clearance, drum speed and feed rate. The optimal combination of operating parameters was that the threshing clearance 35 mm, the drum speed 280 r/min and the feed rate 1.8 kg/s. Through the analysis of variance, it was concluded that the threshing clearance had a very significant effect on the oil sunflower threshing rate and breaking rate, the drum speed was significant, and the feed amount was not significant. Multiple repeated tests were performed under a better combination of operating parameters. The test results showed that the average threshing rate of oil sunflower was 99.01%, and the breaking rate was 2.28%, which met the national standards that the threshing rate greater than 98 % and the breaking rate less than 5%. The better operating parameters of this study are only applicable to the material conditions tested in this paper, but the oil sunflower harvesting operations are complicated, and the factors such as oil sunflower varieties, moisture content, and output are also different. Adjusting the diameter of the threshing concave plate sieve, changing the threshing clearance and other working parameters is to meet the requirements of oil sunflower threshing under different conditions. The research results can provide reference for the design of subsequent oil sunflower threshing device. [ABSTRACT FROM AUTHOR]

Moisture content is one of the important indicators in grain harvesting, trading, storage and processing. High moisture content will lead to a series of problems of grain such as mildew, deterioration, shortened storage time, lower transaction price and higher processing cost. With the development of precision agriculture, accurate detection of grain moisture content can also accurately assess the growing situation of crops, and then provide guidance for the next season’s crop planting. Compared with the drying method, the capacitance method and the electric resistance method, the microwave method is easy to realize the non-destructive measurement of the grain moisture content, which is an important direction of moisture content detection. In the field of on-line detection of moisture content of rice and wheat in combine harvesters, foreign related research started earlier, and enterprises have commercialized, but this technology is still in the research stage in China. Aiming at the problem that the rice-wheat combine harvester is difficult to accurately measure the moisture content of wheat and rice during harvesting operation, this paper studied a non-destructive on-line detection method of grain moisture content based on microwave reflection method, established the grain moisture content measurement model, designed a non-destructive on-line detection device for grain moisture content used on rice-wheat combine harvesters. The device used a 450 MHz microwave measurement module to measure the moisture content of rice and wheat non-destructively. The voltage conversion circuit was designed to convert microwave parameters into voltage signals, and the average filtering algorithm was used for signal filtering to reduce the impact of interference factors. Finally, the moisture content detection model of rice and wheat, which was established by the calibration experiment, was used to calculate the moisture content. The calculation result was displayed on the display in real time via CAN bus communication. Due to the insufficient installation space in rice-wheat combine harvester, the structure of the detecting device was designed and optimized, and the circuit portion and the sampling mechanism were integrated in a compact structure. Based on the above theoretical research, technology development and structural design, this paper carried out laboratory static experiments and field harvesting experiments. The laboratory static experiment used rice and wheat to illustrate the establishment process of the grain moisture content detection model: 30 groups of rice and 30 groups of wheat samples were prepared, moisture contents and voltages calibration experiment was completed, the rice and wheat moisture content detection models was established and the experimental results were analyzed. The field harvesting experiment was verified the practicability and reliability of the grain moisture content detecting device with rice as the test object. The experiment results show that the performance standard deviations of the laboratory static experiment and the field harvest experiment are 0.458 3 and 1.078 0, respectively, and the relative error are around 2.5% and 5%, respectively. Moisture content measuring range of the detection device for rice and wheat is 14%-34%, which meets the project requirements. [ABSTRACT FROM AUTHOR]

Grain loss rate is one of the most important performance index of corn head in mechanized harvesting. Seed harvesting is the main development direction of mechanized corn harvesting. The characters of seed harvesting corn variaty increased the urgency to reduce grain loss on corn head. The paper was proposed to solve the problem of grain loss on corn head. Theoretical analysis was conducted to the snapping process. Corn ear was subjected to pull force by the snapping rolls and the pull force transferred by corn stalk. Corn kernels were divided into 2 types due to their force condition. A kernel at the bottom end of corn ear was subjected to reaction forces by stripper plates, corn cob and the adjacent kernels and shear force by the pedicel. Kernels out of contact with the stripper plates were subjected to reaction forces by the adjacent kernels, pull force and shear force by corn cob. As the impact force was related to the impact time according to the theorem of impulse, the paper analyzed collision model between corn ear and stripper plates in the snapping process. A mathematical model was obtained about the impact time and intrinsic parameters of the system. The impact time was dependent on system mass, stiffness coefficient and damping coefficient, which lays on the mechanical structure and materials of collision objects. So, the impact force would decrease as the impact time could be prolonged by reducing the stiffness coefficient and raising the damping coefficient. The quantity of shed kernels could be reduced consequently. The paper proposed a corn head with wheel type rigid-flexible coupling snapping device to reduce loss. The corn head consisted of the frame, gear-box, snapping rolls, gathering chain, wheel type rigid-flexible coupling snapping device, and chain wheels. The wheel type rigid-flexible coupling snapping device consisted of snapping wheel axle, spring seat axle, supporting axle, buffer spring, and snapping wheel frame. Force analysis was conducted on the snapping wheel. According to the force conditions and dimension boundary condition, the structure diameters of snapping wheel, snapping wheel frame, and buffer spring were confirmed. In order to obtain the optimal parameters with the minimum loss rate of wheel type rigid-flexible coupling snapping device, the optimization experiments were conducted of the factors at 3 different levels. In the optimization experiments, the snapping wheel radius was designed at 10, 15 and 20 mm respectively, the flexible body thickness was at 2, 4 and 6 mm respectively, the snapping rolls rotating speed at 700, 800 and 900 r/min respectively. The Response Surface Analysis method was used to design the experiments. The software Design-Expert 8.0.6.1 was used to analyze the data. Regression equation was induced according to the experiment and analysis above. The optimal combination of wheel type coupling snapping device was as follows: The snapping rolls rotating speed was 700 r/min, the snapping wheel radius was 15 mm, the flexible body thickness was 4 mm. Verification contrast test was conducted between corn head with wheel type rigid-flexible coupling snapping device and the one with snapping rolls and stripper plates on corns at different moisture contents. As the kernels moisture contents were 21.8%, 16.7% and 13.4%, the grain loss rate decreased 53.4%, 48.6% and 47.0% respectively. This study provides not only theoretical basis but also design reference for the improvement of corn harvester design. [ABSTRACT FROM AUTHOR]

Castor is one of the top ten oil crops in the world, which has a extremely high economic value. For a long time, the harvesting of castor bean has relied on manual operations, so the development of the castor industry have been greatly restricted by the high labor intensity and low efficiency. At present, there are few studies on harvesting machinery of castor, and the mechanization of castor harvesting is still in the initial stage. The existing castor harvesting equipments are not suitable for the growth features of castor, which has the problems of high loss rate and high damage rate. In order to solve these problems, a brush-roller harvesting method was proposed in this paper. The harvesting principle of brush-roller castor harvester is that the castor capsules are separated from the plant by the brushing force caused from the brush wire. According to the physical characteristics and planting mode of castor, the picking mechanism of brush-roller castor harvester was designed. Firstly, the structure of the picking mechanism was introduced, the picking mechanism is mainly composed of crop divider, brush roller, screw conveyor, transfer case, et. Then, the kinematic and mechanical analysis of the working process of the mechanism was carried out, so as to determine the structural parameters and working parameters of each part of the picking mechanism. In order to improve the harvesting quality of castor, we conducted a field experiment in October 2020 in Hohhot, Inner Mongolia. In the field experiment, Box-benhnken response surface design theory was used on the basis of single fator experiment to optimize the working parameters of the picking mechanism. The picking rate, the breakage rate and the impurity rate were used as the evaluation indexes of working quality. And the moving speed, the brush roller speed and the length of brush wire were taken as three factors influencing the working quality. The quadratic polynomial response surface regression model was established, and the influence of various factors on the response value was analyzed. From the regression model and variance analysis of regression equation, it could be seen that: lower moving speed, moderate brush roller speed, and shorter brush wire led to higher picking rate; Lower moving speed, lower brush roller speed, and longer brush wire led to lower breakage rate; Higher moving speed, lower brush roller speed, and longer brush wire led to lower impurity rate. The experiment results also showed that the significant effects of moving speed, length of brush wire and brush roller speed on increasing the picking rate were in a decreasing order. The significant effects of brush roller speed, length of brush wire and moving speed on reducing the breakage rate and the impurity rate were in a decreasing order. At the same time, the factors were multi-objective optimized comprehensively, and the optimization results were verified by experiments. The results showed that the optimum parameters were: 0.72 m/s for the moving speed, 372 r/min for the brush roller speed and 57 mm for the length of brush wire. Under these conditions, the picking rate was 91.36%, the breakage rate was 0.18%, and the impurity rate was 11.67%. The measured values of each index were in good agreement with the theoretical optimization values, which meant that the model established was reliable and could be used for optimization. The results can provide a reference for further improving the structure design and working parameters optimization of the brush-roller castor harvester. [ABSTRACT FROM AUTHOR]

As a main grain production equipment, the combine wheat harvester plays an important role in grain production, and its technological development level is an important indicator of the degree of agricultural modernization. However, during the harvesting process, the working parts of the harvester interact with the crop to be harvested, so that the dust originally attached to the surface of the crop is disturbed and separated from the surface of the organism, forming floating and flying dust, some of which are scattered around the harvester, seriously affecting The driver’s body is healthy; some infected plants carry diseased dust, which is more harmful to the human body; more dust is dispersed in the air with the wind, causing a wider range of air pollution and increasing the amount of inhalable particles in the air. This has become one of the sources of air pollution during the crop harvest season. In order to understand the dust generation status and the characteristics of the dust composition, this paper first conducts the dust concentration and distribution test on the operation site of the combine wheat harvester .The result is as the header and tail of harvester are the main areas where dust is generated, Excessive dust mass concentration will harm the health of workers .The characteristics of the dust sample was tested results as follows: the proportions of dust with a particle size of 10μm and 100μm or less are 45% and 92%, the dust is mostly composed of minerals, grease and carbohydrates. The dust measurement test revealed for the first time the dust generation and dust composition characteristics of combine wheat harvester operations in the rice-wheat (oil) rotation area in southern my country. On this basis, a dust suppression system installed on the combine wheat harvester was designed. The system adopts the working principle of negative pressure dust suction and filter cartridge dust collection. The system utilizes the power of the existing combine wheat harvester and can change the working parameters of the fan at any time to meet a variety of field working conditions. Conduct field tests on the dust suppression system. Through theoretical analysis to determine the main factors that affect the efficiency of the dust suppression system. Taking the harvester header dust suppression efficiency and harvester tail dust suppression efficiency as the test indicators, and the harvester speed, fan speed and environment humidity as the test factors. Using Box-Behnken central combination test method, the three-factor and three-level test are carried out. A mathematical regression model of various factors and test indicators was established. Through variance analysis and response surface analysis, the influence of harvester speed, fan speed and environment humidity on the test indicators is obtained. Use Design-Export8.0.6.1 data analysis software to fitting and optimization analysis of the test results, the optimal parameter combination is obtained as follows: harvester speed 3.73 km/h, fan speed 3 507 r/min, and ambient humidity 56%. On this condition, the efficiency of the header dust suppression is 76.8%,the efficiency of the tail dust suppression is 79.6%. The optimal working parameters are tested and verified to verify the feasibility of optimizing the optimal parameter combination, the minimum fan speed of the dust suppression system to meet the dust suppression requirements under difficult working conditions is 3 332 r/min. This research can provide a basis for the design of the harvester dust suppression system. [ABSTRACT FROM AUTHOR]

The stem tip of vegetable sweet potato is an excellent nutritious and healthy food, which is widely used in many countries. It’s estimated that the total value of Chinese vegetable sweet potato’s market is about tens of billions of yuan, which means it has a promising future. Due to the difficulties of the long harvest period, high harvest requirement, and low mechanized level, the high cost and low efficiency in harvest is prominent. As such, it decreases the motivation of the farmers deeply. Also, the market still has a strong need for the stem tip harvester urgently. In order to fill the blanket in the mechanized harvest on stem tips of vegetable sweet potatoes in China, and to solve the current problems, in this research, we designed a stem tip harvester for vegetable sweet potatoes in combination with agronomy, which was composed of the reeling, cutting, conveying and collecting devices. It could finish cutting, conveying and collecting the stem tips for vegetable sweet potatoes every single row in one operation. In this paper, we introduced the harvester’s working theory based on analyzing the whole machine’s mechanical structure. To improve the integrity rate of stem tip, to lower the missing rate in cutting, to lower the stubble height and to improve the harvester’s working quality, we did a test on the harvester’s working parameters, using Box-Benhnken's central combination test method based on the single factor test. Three-level quadratic regression orthogonal experimental design was done through the forward speed, the reel speed and the reciprocating cutter line speed. The model of response surface was established to research and analysis the machine’s working quality due to different factors. Finally, the optimization of machine operation parameters was realized. The results showed that the prominent order in the stem tips’integrity rates was the reel speed > the reciprocating cutter line speed > the forward speed. The prominent order in the stem tips’missing rate was the forward speed > the reciprocating cutter line speed > the reel speed. The prominent order in the stem tip’s stubble height was the reel speed > the forward speed > the reciprocating cutter line speed. In 2019, the test was done in three times to verify the model’s correction in Baiba test base, Nanjing Research Institute for Agricultural Mechanization. The field test results showed the optimal working parameters were the forward speed 0.38 m/s, the reel speed 26 r/min, and the reciprocating cutter line speed 0.60 m/s. The integrity rate of stem tips was 97.10%, the missing rate was 12.11%, and the stubble height was 62.09 mm. The error was in the range of 5% compared to the theoretical optimization. Compared with the single manual picking efficiency of 0.001 hm²/h, the operating efficiency of this machine can reach 0.1 hm²/h, The operation effect of the machine was obviously improved compared with that of manual operation, better to meet the requirements of the vegetable sweet potatoes’stem tips machinery harvesting. The test research supplies a strong support and theoretical basis to the mechanical development of the harvester for vegetable sweet potatoes’stem tips. [ABSTRACT FROM AUTHOR]

Fruit and vegetable picking grippers are important technology to achieve rapid and labor-saving harvest. However, most of the existing fruit and vegetable picking grippers still use traditional rigid or underactuated grippers, which often cause fruits and vegetables damage by the heavy mass and lack of high-precision control, and have poor compliance in the operation process. In recent years, inspired by soft creature’s tentacles, soft robotic grippers have appeared and been used in robotics due to the emergence of soft robots. Soft robotic gripper, which is made of flexible material, is a new type of gripper for general purposes with grasping and holding capabilities enabled by a simple control scheme. Under the infinite degrees of freedom, the soft robotic gripper can change its shape and size corresponding to the load in a large range. These advantages overcome the defects of traditional fruit and vegetable picking robots, such as rigidity and poor adaptability. Moreover, soft robotic gripper is easy to manufacture and can be integrated with manual operation without any large-scale safe requirement. This paper gives a research on limitations of the traditional grippers and summarizes the characteristics of ideal picking grippers of fruit and vegetable. In addition, the concept of soft robotic grippers is introduced in detail, and the current development status about soft robotic grippers is described. The manuscript also summarizes the progress and superiority of soft robotic grippers in fruit and vegetable picking as well as strong adaptability to the environment. The characteristics of the soft robotic grippers driven by the common driving mode including pneumatic, cable, shape memory alloy and electroactive polymer mode have been analyzed in the process of fruit and vegetable grasping and picking. Compared with the rigid grippers, in addition to the simple control and mechanism, the soft robotic grippers have high-degree flexibility, adaptability and versatility. Based on the related work, the problems of modeling and control of fruit and vegetable picking devices have been discussed, and possible solutions of soft robotic grippers are also summarized by means of analysis and classification. We can choose the appropriate control methods according to the surface characteristics of picked fruits and vegetables. Finally, we conclude that multi-sensing, variable stiffness, multi-functional composite materials, as well as control strategies of fusion intelligence will be future development directions of fruit and vegetable picking grippers with the progress of micro-sensors and biomaterials. This research will provide theoretical and technical guidance for the development of fruit and vegetable picking grippers. It is expected that more fruit and vegetable picking operations could be carried out by soft robotic grippers, and the application will effectively reduce the damage rate of fruit and vegetable picking. As a new-generation operating device, the soft robotic grippers involve the development of materials, chemistry, machinery and other multidiscipline. Further studies are required to improve its design, controllability, manipulating methods, and so on. [ABSTRACT FROM AUTHOR]

Although China is a vegetable growing country, but the degree of mechanization of vegetable production is low, with China's urbanization and industrialization of the advance, arable land gradually less, so the vegetable cultivation plant more and more people pay attention. Facilities vegetable cultivation is an important way for vegetable cultivation. However, the level of mechanization of vegetable greenhouses is less than 25%, and the comprehensive mechanization level of vegetable production is about 20%, while that of leaf vegetables in China accounts for 30% to 40% of total production. Therefore, the development of efficient and stable facilities vegetable harvesting machinery is the premise to achieve the vegetable plantation and production process automation, and to achieve agriculture, especially vegetable production mechanization is of great significance. In this paper, the height of the vegetable pickling machine can not meet the requirements, the distance of the rhizome exposed is too short, which leads to the phenomenon of vegetable cutting and harvesting. Therefore, the model of the vegetable harvester is established, and the problem of cutting is analyzed. Based on the analysis of the above and below parts of the vegetable stem in the process of drawing, the mathematical parameters of the drawing force were analyzed, and the key factors affecting the pulling force of the vegetables were the height of the vegetables and the height slope. Through the tensile test of the rhizome of the vegetable sample and the compression test of the stem of the vegetable sample, the mechanics parameters of the vegetable were obtained, and the necessary theoretical support was provided for the simulation parameters of the extraction efficiency of the vegetable and the other research. The distinct element method (DEM) is a numerical simulation method for dealing with discontinuous medium problems. And it is widely used in the field of bulk material processing. EDEM software is a general CAE analysis software based on discrete element method, which is commonly used to simulate and analyze particle processing and operating system in industry and agricultural production. At present, its application in crop harvesting has not been reported, but it has been successfully applied in the field of agriculture, especially in the treatment of soil matrix. The discrete element simulation model of vegetable drawing process was established by using discrete element software EDEM, and the optimal drawing force and drawing effect were determined by studying the mechanism of pulling the vegetables. According to the simulation analysis, the relationship between the pulling force of vegetables and the displacement of vegetables and the simulation process of vegetable drawing were obtained. It was determined that the minimum drawing resistance was 26.87 N when the optimum drawing distance was 20 mm. The maximum safe draft load of vegetable rhizome was 37.5 N and the maximum safe compression load of vegetable stem was 84.36 N under the condition of safety factor of 1.1, using small universal testing machine. According to the upper and lower limits of the drawing force and the mathematical parameters of the drawing, the inclination angle of the planting trough to meet the planting of 1~6 vegetables was determined to be 17.8°. And at this angle of inclination, the maximum thrust value of the stem of the vegetable is less than the maximum destructive force of the vegetable 84.36 N. The final working parameters were applied to the single - row prototype test, and the good harvesting effect was obtained, which verified the rationality of the key parameters of the vegetable and vegetable harvest. [ABSTRACT FROM AUTHOR]

Recently, as scientific research has been further explored, the health care functions of the Lycium barbarum (L. barbarum) in anti-oxidation, anti-aging, anti-fatigue, protecting liver, improving body immunity, eye protection and other aspects have been further confirmed. Its unique and nutrient-rich health function is recognized gradually in western countries, and the market demand of the L. barbarum is expanding each year. The L. barbarum blooms and bears fruit continuously during the growing season which begins in mid-May. Depending on the picking time around the year, the L. barbarum fruit can be divided into spring, summer and autumn fruit. In order to make dried L. barbarum keep good commodity characters, the L. barbarum is harvested at 80 percent maturity. The full bearing period of L. barbarum is from May to September every year, which is the picking peak of L. barbarum. It must be picked once about every 7 days. For centuries, the mechanized harvesting of L. barbarum has been a tough problem. Its harvesting has been artificial, which brings about low picking efficiency and high harvesting costs. With the continuous expansion of L. barbarum acreage, fruit picker has been increasingly scarce, which will be followed by rising picking costs. It's no doubt that the picking has become the bottleneck restricting the development of L. barbarum industry. Aiming at realizing the harvesting mechanization of L. barbarum and establishing the theoretical guidance and design basis for the L. barbarum picking machine, the vibration picking mechanism of L. barbarum plant's fruiting branches in picking was studied, the parameter optimization and simulation analysis was done to determine exciting force vector and rotational speed of driving wheel, and an experiment was conducted to prove the obtained rotational speed of driving wheel in this paper. First, we analyzed the working principle of the picking machine to get the vibration picking mechanism. The fruiting branches' model was simplified and the L. barbarum plant's fruiting branches' physical model and mathematical model were got, which were solved by equation solutions. We then obtained the forced vibration response of the fruiting branch and the forced vibration picking inertia force exerted on ripe and unripe fruits and flowers on each node. Second, 10 L. barbarum trees were selected as the test samples. We measured the binding force and mechanical parameters of the L. barbarum and fruiting branches, such as the number of ripe and unripe fruits and flowers, diameter, length, elastic modulus, damping ratio of fruiting branches, and node number. Based on the principle of successful picking which is the ripe can be picked and the other parts wouldn't be picked, the parameters were optimized, and the inertia force changes of the fruits and flowers with rotational speed were simulated with the MATLAB software. Simulation results showed the reasonable rotational speed was 2 868.84-2 871.21 r/min. Finally, rotational speeds of 7 levels which came from the interval and beyond the interval were selected in the experiment. Using a self-developed experimental L. barbarum picking machine, the test was conducted at planting base of L. barbarum of Ningxia Academy of Agriculture and Forestry Sciences, and the fruit distribution before and after picking was compared. Experiment result showed that reasonable rotational speed was 2 870 r/min, which is within the reasonable simulation interval of rotational speed. Under this rotational speed, picking efficiency of ripe L. barbarum was 815 grains per minute, the picking rate of ripe fruit was 86.70%, the picking rate of unripe fruit was 7.36%, and the picking rate of flower was 7.43%. The damage rate of fruit was 8.62%. The efficiency ratio of machine to worker was 5.43. Due to the actual picking environment, this result differs from simulation conclusion that the ripe is picked totally and none of the unripe and flowers is picked. The results can provide a reference for the development of L. barbarum vibration picking machines. [ABSTRACT FROM AUTHOR]