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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]

Agricultural machine automatic navigation is one of the key technologies in precision agriculture technology system, the in-depth study is important in scientific research, application and social values. In this paper, we investigated the navigation problems in the application of the farm work, including slow on-line speed, bad on-line stability, and poor adaptability of bumpy complex road surface. These problems can be summarized as the speed and stability problems of track tracking in the case of large position deviation or large course deviation. Through the analysis of the work principle and control parameters function of the navigation, a conclusion is made that the correct speed and stability of the position deviation and course deviation of agricultural machinery can be improved by allocating the weight of the position deviation wheel angle decision quantity and course deviation wheel angle decision quantity reasonably. Then in this paper, we developed the navigation control algorithm based on the agricultural machine kinematics model and the pole optimal configuration theory. Because of the small angle linearization of course deviation angle and wheel angle during the deducing, the control law can achieve good control effect only in the ideal straight path tracking control with small position deviation, course deviation, and wheel angle. Based on this, a path tracking control method of aiming pursuit model for agricultural machine navigation was proposed aiming at improving the on-line speed, stability and adaptability to complex road surface of the automatic navigation system of agricultural machine. In this method, we selected a tracking target point on the planning path of agricultural machine ahead, and tracked the target point by controlling the steering wheel angle. The direction of the agricultural machine vehicle center point to the target point was called as the aiming course. The desired steering angle would be larger when the deviation was larger between the course of agricultural machine and the aiming course, with a rapid correction of aiming course deviation to achieve the goal of fast tracking the target path. On the other hand, the desired steering angle would be smaller when the deviation was smaller between the course of agricultural machine and the aiming course, with a stable tracking to aiming path to achieve the goal of stable tracking the target path. In this model, the steering wheel angle was designed to be K times of the aiming course deviation and K was called as control gain. The length of the projection of the agricultural machine vehicle center to the target point vector on the planning path was named as the preview distance. The control gain and the preview distance were two important parameters that affected the control effect of the model. In this paper, there were three steps to prove the feasibility of the method. The control gain K and the preview distance were set up by referring to the result of the pole optimal configuration method based on the kinematic model of agricultural machine. By comparing two methods formula, the position deviation wheel angle decision quantity had a linear relationship with the position deviation in the kinematics model method and the position deviation wheel angle decision quantity had an inverse tangent function relationship with the position deviation. The inverse tangent function relation was more beneficial to maintain proper weight of position deviation wheel angle decision quantity and course deviation wheel angle decision quantity that would make the path tracking control of agricultural machinery navigation more rapid and stable. Simulation analysis results of aiming pursuit model algorithm in different position and different course deviation showed that the proposed method had a fast and stable path tracking performance and good robustness and adaptability to the navigation path tracking. The test results of agricultural machine showed that the control method proposed in this paper had a good effect in the rapid responsibility and line tracking performance. In the case of 0.5, 1, 1.5 m initial position error, the on-line time was 6.8, 8.2, 9.4 s, respectively, the corresponding travelling distance was 6.73, 8.11 and 9.33 m, respectively and the corresponding overshoot was 5.2, 7.0, 8.5 cm, respectively. The maximum error of straight-line path tracking for bumpy uneven field was not more than 4.23 cm, the mean value of the absolute value of the error was 1 cm, and the standard deviation was 1.25 cm, which satisfied the operation requirements of agricultural machine. [ABSTRACT FROM AUTHOR]

Agricultural machinery purchase subsidy is an important agrarian policy, its policy effect has been widely concerned by scholars. However, very few studies have discussed the spatiotemporal difference, agricultural machinery types difference and endogeneity of subsidy’s policy effect. The purpose of the present study is to make policy effect evaluation more accurately, and analyze the spatiotemporal difference and agricultural machinery types difference of policy effect. Different from existing studies, the present study uses a large sample collected from 15 089 observations in 3 287 households at 18 provinces from 2008 to 2018 by China agriculture research system (rapeseed) farmer fixed observation point and employs unbalance panel fixed effect model, panel high-dimensional fixed effects model, Box-Cox model, quantile regression model to calculate the differential policy effects between different year, topographic regions and types of agricultural machinery purchase subsidy on farmer’s agricultural machinery self-investment. In addition, instrumental variables fixed-effects panel-data models, Tobit fixed-effects panel-data models and Heckman sample selection models were used for the robust test. The result showed that 1) On the whole, agricultural machinery purchase subsidy had an obvious incentive effect, effectively promote farmer’s agricultural machinery self-investment, the marginal effect of agricultural machinery purchase subsidy on farmer’s agricultural machinery self-investment was 2.530 8. 2) The effect of subsidies varies significantly between plain and non-plain areas. Subsidy’s marginal effect in plain county was 1.408 5, subsidy’s marginal effect in hill and mountain county was 3.108 2. Subsidy policy was more effective in hill and mountain areas. 3) Generally, subsidy’s incentive effect fluctuated significantly between the years, crowding-out effect was showed in some years. The number of years in which the policy effect declined from the previous year was equal to the number of years in which it rosed from the previous year. 4) On the whole, the subsidy effect was enhanced with the increase of the value of agricultural machinery, and the policy effect was higher for large and medium-sized agricultural machinery. Accordingly, this paper suggested that: 1) In the future, agricultural machinery purchase subsidy should continue to implement. 2) Agricultural machinery purchase subsidy should tilt appropriately to non-plain areas and large and medium-sized agricultural machinery continually. Appropriate R&D subsidies can be given to agricultural machinery production enterprises to research and develop large and advanced machines and suit machines which used in hilly and mountainous areas. Encourage local governments to include large and advanced machines and machines which was suitable used in hilly and mountainous areas into the new agricultural machinery subsidy pilot catalogue timely. Accelerate the transformation and application for new machine products. 3) Adjust or improve the subsidy mode according to the implementation situation and agricultural mechanization development situation. [ABSTRACT FROM AUTHOR]

To solve the problems of low removal rate and incomplete separation for the current longitudinal-axial-flow combined harvester in the case of harvesting rice and wheat, a segmented longitudinal-axial-flow threshing device was designed in this paper. The threshing device mainly comprised a tapered threshing roller, a concave sieve with adjustable threshing strength, a 360° separation device and an electric control system for operating parameters. Through the single factor tests, the optimal switching states of the concave sieve with adjustable threshing strength for rice and wheat threshing was obtained respectively. In order to find out the influence rule of the working parameters of the device on the threshing effects and the optimal parameter combination, the multi-objective optimization tests were carried out. The rotational speed of roller, the angle of deflector, the threshing gap of concave sieve, the separation gap of concave sieve and the feeding rate were selected as the influence factors and the crushing rate, impurity rate and loss rate were selected as the test indexes. The test results showed that the significant sequence of influence of threshing parameters on the crushing rate was the rotational speed of roller, the threshing gap of concave sieve, the angle of deflector, the feeding rate, the separation gap of concave sieve. The significant sequence of influence of threshing parameters on impurity rate was the rotational speed of roller, the angle of deflector, the threshing gap of concave sieve, the feeding rate, the separation gap of concave sieve. The significant sequence of influence of threshing parameters on loss rate was the rotational speed of roller, the angle of deflector, the threshing gap of concave sieve, the feeding rate, the separation gap of concave sieve. Through multi-objective parameter optimization analysis, the optimal working parameters combination for wheat threshing were determined that the rotational speed of roller was 905 r/min, the angle of deflector was 69°, the threshing gap of concave sieve was 18 mm, the separation gap of concave sieve was 19 mm and the feeding rate was 4 kg/s. The field verification tests were carried out using the optimal working parameters combination. The results indicated that the crushing rate was reduced from 1.46% to 1.00%, the impurity rate was reduced from 1.85% to 1.43% and the loss rate was reduced from 1.72% to 1.20% compared with the conventional longitudinal-axial-flow threshing device. All the relative errors between the measured values and the optimized values were less than 5%, the working indicators met the requirements of relevant national standards. The device effectively solved the problems of high crushing rate, unclean threshing and incomplete separation, the research results can provide reference for the structural improvement and operation parameters optimization of the threshing device of longitudinal-axial-flow combined harvester. [ABSTRACT FROM AUTHOR]

Mechanical precision seed metering device is widely used in precision seeding technology because of its simple structure and uniform seed metering. Seed filling process is the key link of the whole operation process of seed metering device. The precision metering device is mainly divided into internal filling, side filling, external filling, and the combination of side filling and external filling according to the seed filling mode. In the operation process, the internal filling mode mainly completes the seeding operation through the process of type-hole filling and gravity clearing, and the seed motion parameters close to the type-hole directly affect the seeding quality of the machine. The rotary type-hole cotton precision seed metering device is a kind of mechanical precision seed metering device. In order to solve the problem of missing seed in the process of filling, the influence of the motion parameters of rotary type-hole cotton precision seed metering device on the filling performance by establishing the kinematic model of the seed filling process in this paper. Using the discrete element simulation software to analyze the speed change trend of cotton seed falling into the type-hole and the influence of seed wheel vibration frequency on seed group disturbance. Taking the vibration frequency of seed wheel, vibration offset angle of seed wheel and rotating speed of metering device as the test factors, and taking the qualified rate of seed spacing, replaying rate and missing rate as the test indexes, three factors and five levels of positive traffic rotation combined test are carried out to explore the influence of each factor on seed metering performance. Design expert 8.0.6 software is used to analyze the test results and optimize the regression model. Single factor simulation test results show that the instantaneous speed of cotton seed increases with the increase of the rotating speed of the seed wheel, the instantaneous speed of the cotton seed is less than that of the seed wheel when it is filled into the type-hole, the cotton seeds with lower relative speed have better filling effect. When the vibration frequency of the seed wheel is 7 Hz, the average value of the normal force of the seed group is the smallest, which is 0.75 N, at this time, the internal friction of the seed goup is the smallest, the cotton seed is easy to be taken by the type-hole, and the seed filling performance of the seed metering device is improved. The simulation results of quadratic regression general rotation combination show that when the rotating speed of the seed metering device is 12.59 r/min, the vibration offset angle of seed wheel is 8.06° and the vibration frequency of seed wheel is 6.08 Hz, the qualified rate of seed spacing reaches the maximum of 94.5%, and the leak seeding rate is 2.9%, the repaly rate is 3.3%. On this basis, the platform validation test was carried out with Xinluzao No.61 cotton seed as the test object. The test results showed that when the rotating speed of the seed metering device was 12 r/min, the maximum qualified rate of the seed spacing was 94.65%, the error between the rotating speed of the seed metering device and the simulation test is 5.4%, which verifies the accuracy of the simulation results. This study can provide a reference for the structural optimization of the key components of the rotary type-hole cotton precision metering device. [ABSTRACT FROM AUTHOR]

In the implantation process of garlic mechanized seeding, under the strong coupling among garlic seeds, soil and parts touching it, the verticality of adjusted garlic seeds is very easy to reduce again, thus affecting the final garlic output and garlic quality. How to ensure that garlic seeds are planted in an upward vertical direction has become a key technology to be solved. To solve this problem, this paper took the planetary wheel garlic planter designed in the early stage as the research object, introduced its structure and working principle in combination with the whole garlic planter, realized the adjustment of the opening and speed ratio of the inserting duckbill by processing the cams of different planters, and changed the opening phase angle of the inserting duckbill by adjusting the circumferential position of the cams installed in the machine. Based on the establishment of garlic inserting seed model and the analysis of the process, the tip motion equation of the duckbill was established and imported into CAXA software to generate the movement track. Through the analysis of the movement track under different parameters, it is clear that the key factors that affect the verticality of garlic seeds after planting are the linear speed of the inserting duckbill, the opening phase angle and the ratio of the opening angle of spigot duck's beak to the center angle corresponding to the cam convex section (the opening and speed ratio). In order to verify the correctness of the theoretical analysis, a garlic planting test-bed was developed, and the indoor experiment of Cangshan garlic planting was carried out. Through the single factor experiment, it was determined that the value range of the linear speed of the duckbill was 200-500 mm/s, the range of the opening phase angle was 0-20°, and the range of the opening and speed ratio was 1-2. In order to obtain the optimal parameters of these three factors, the Box-Benhnken central composite test method was used to design the linear velocity, opening phase angle and opening velocity ratio of the spilt duck's beak by three factors and three levels quadratic regression test. The sowing test was carried out, and the response surface mathematical model was established by using Design-expert software. The key parameters affecting the verticality were comprehensively optimized. The optimal working parameters are as follows, the linear speed is 200 mm/s, the opening phase angle is 20°, the opening and speed ratio is 2. In order to verify the performance of the inserter using the optimized parameters, field experiments were carried out. The results showed that the average vertical degree of garlic seeds in the optimal parameter operation was 63.2°, which was 21.8% higher than that before. It not only met the requirements of garlic planting vertical degree, but also further improved the integration of agricultural machinery and agronomy, which improved the guarantee for large-scale mechanized vertical sowing of garlic. [ABSTRACT FROM AUTHOR]

The generation of power shift tractor promotes the automatic driving of agricultural machinery to the direction of unmanned, and the automatic obstacle avoidance of agricultural machinery has become a key issue to be solved. Most of the existing obstacle avoidance path planning adopts the shortest tangent method, which has the advantages of fast and simple path generation and short track, but the curvature of the path curve is discontinuous and there are corner inflection points, which make the tractor front wheel angle suddenly change and affect the obstacle avoidance accuracy. In this paper, for the curvature discontinuity of the shortest tangent path curve, poor tracking control accuracy and low precision of agricultural machinery model, the third-order bezier curve optimization method was used to form a continuous smooth agricultural machine obstacle avoidance path. The optimized curve curvature was continuous and the obstacle avoidance path was smooth with no turning points, which was conducive to the control of agricultural machinery driving. The linear control model of agricultural machinery movement was established by chain control theory, and the PI controller was used for corner compensation to improve the accuracy of agricultural machinery obstacle avoidance. The simulation of the path tracking control method was completed. The simulation results showed that the heading error angle of the agricultural machinery was mostly in the range of - 0.06-0.06 rad, the lateral position error was less than 13 cm, and the front wheel steering angle changed gently with no significant mutation, indicating that the control method of the obstacle avoidance path control method had a high precision, and the agricultural machinery can drive according to the preset trajectory. The ploughing operation test was carried out, and the Dongfanghong LF954-C power shift tractor was used, which can automatically start, stop, shift, and implement the lifting operation of the farm. The tractor was equipped with the Beidou agricultural autopilot with the straight running accuracy of ±2.5 cm. Ultrasonic radar and image recognition technology were used to perceive obstacles in the working environment. The farm implement was a 250 cm wide plow. A haystack obstacle was set on the machine working path with a contour radius smaller than the minimum turning radius of the tractor. The results of the plowing operation test showed that the machine can automatically complete the straight-line driving, farm implement lifting, automatic obstacle avoidance, farm implement falling, and continuous straight-line operation. The obstacle avoidance accuracy of the bezier curve was 5.21 cm, and the tracking control effect of the curve path was well. The accuracy of the agricultural machine continuing to travel in a straight line after obstacle avoidance was 1.98 cm, which indicated that the path tracking control method can ensure the tractor straight-line automatic driving after obstacle avoidance. The above results showed that the obstacle avoidance path and control method showed good robustness and adaptability in uneven ploughing land and can meet the obstacle avoidance requirements of tractor operation. [ABSTRACT FROM AUTHOR]

As a large agricultural country, there are still more than 40% of people in China engaging in agricultural production activities. In recent years, the soil erosion and desertification have been in serious state, and the arable land has decreased year by year, which means that it is very necessary to develop agricultural technology to improve crop yield per unit area. Therefore, in recent years, China has vigorously developed agricultural greenhouse cultivation which has characteristics of high input, high technology and high yield. Agricultural greenhouse cultivation is an important part of China’s agricultural production. In 2014, the area of greenhouse in China was up to 4.109 million hm2. With the promotion of precision agriculture, the technology of modern agricultural greenhouse cultivation is developing towards precision. Precision fertilization is one of the important parts of precision agriculture operation system. Due to that the structure of modern agricultural greenhouse is closed, and the planting area is limited in China, the large agricultural machinery cannot be applied to greenhouse operations, leading to that the mechanization level in greenhouse production is lower than other developed countries in the world. At present, the fertilization in greenhouse in China is still mainly relying on manpower. Because of the increasing labor cost and decreasing yield in greenhouse production, the profits of greenhouse is reduced. In the pursuit of more profit, people’s requirements of precision fertilization in greenhouse are increasingly urgent. This paper mainly introduced a small, precise and practical fertilizing machine. This machine was mainly used in greenhouse and it was intelligent and automatic. The fertilization machine used ARM9 S3C2440 microprocessor as the core of circuit control module. It was equipped with a fertilizer level monitoring alarm device, and would alarm automatically when the fertilizer level was less than 15 cm, so that the staff could add fertilizer in time. The machine used the Geneva mechanism as fertilizer metering mechanism. By controlling the pulse frequency of the stepping motor, the amount of fertilization could be controlled so as to achieve quantitative precision fertilization. The three-dimensional model of the fertilization machine was built by the SolidWorks. The intensity check was performed for its main parts of the force with simulation. All those verified that the structure could meet the requirements of hardness and intensity. The fertilization effect was simulated by the EDEM (enhanced discrete element method), a general CAE (computer-aided engineering) software applied to the discrete element method. In the simulation, the speed of the sheave was set to 10 r/min, the output time step was 0.05 s, and the total simulation time was 5 s. It was found that there weren't flying particles during the process of simulation, which showed that the selected rotational speed of the sheave and the parameter of the simulation time step were reasonable. The sheave grooves in the process of simulation were almost filled with the fertilizer particles, which proved that the device could get a good effect of fertilization and the parameter of the sheave was reasonable. The brush structure in the fertilization device could effectively get rid of the extra fertilizer particles and supplement fertilizer particles for other incompletely filled groove in order to make sure every groove could discharge a certain amount of fertilizer. The simulation results showed that the fertilization device could discharge the fertilizer particles evenly, stably and continuously. By properly controlling the rotation speed of the drive shaft, the fertilization machine could achieve the goal of precise fertilization. The results show that maximum error of fertilizer test actual value and the theoretical value is 2.42%, less than 3% under four kinds rotational speed (5, 10, 15, 20 r/min). Therefore, the machine designed in this paper could greatly improve the automation level for greenhouse production and reduce the labor intensity of fertilization in greenhouse. It has broad applicability and popularity in our facility greenhouse production. [ABSTRACT FROM AUTHOR]

Astragalus smicus, also known as Chinese milk vetch, Zi yunying and so on, is one of the main winter green manure crops in paddy fields of central and southern China, it has the advantages of reducing fertilizer input, improving soil fertility, increasing crop yield and quality, and protecting ecological environment, and has strong nitrogen fixation ability and high utilization efficiency. In recent years, the production machinery of Astragalus smicus has been developed and applied rapidly in terms of capacity and utilization efficiency, but its development still lags behind. Ditching and sowing are important links in the production of Astragalus smicus. The yield of Astragalus smicus is largely determined by the quality of sowing, and ditching operation can make Astragalus smicus grow well in low-humid field with poor drainage or sandy soil with poor fertilizer and water retention. Astragalus smicus is often used as green manure in paddy field, but high stubble retention, large amount of straw, insufficient in sowing height of existing other sowing equipments, working parts easily clogged, etc., bring difficulties for mechanized production of Astragalus smicus. In order to solve the influence of machine-harvested rice stubble on mechanized production of Astragalus smicus, aiming at the problems of low quality and low production efficiency in independent ditching and sowing links at present, a Astragalus smicus ditching and sowing machine which suitable for machine-harvested rice stubble field was developed. A height adjustable sowing device was designed, by which the sowing components could be lifted to a proper position according to the residual straw situation in the field. The special seed-metering wheel and quantitative evenly-sowed device for Astragalus smicus were developed to achieve precision sowing and improve the sowing uniformity. The structure and working parameters of the double-disk ditching components were determined. The variation coefficients of ditching width and depth determined by field experiments were less than 6%, which met the drainage requirements of Astragalus smicus growth process. The multiple factor experiments and regression analysis of the test data were carried out by Design-expert software, the results showed that forward speed of machine, rotation speed of seed-metering wheel, seed-uniforming cylinder diameter significantly affected the sowing performance, the results of variance analysis showed that the rotation speed of seed-metering wheel had the greatest influence on the emergence rate and coefficient of variation of sowing uniformity, while the forward speed of machine had the least influence on the emergence rate and coefficient of variation of seed-metering quantity consistency, regarding the coefficient of variation of sowing uniformity, the most influential factor was seed-uniforming cylinder diameter, and the minimum impact factor was the rotation speed of seed-metering wheel, the optimal factor parameters combination which affected the sowing quality of Astragalus smicus ditching and sowing machine was as follows: forward speed of machine was 4.6 km/h, rotation speed of seed-metering wheel was 44 r/min, seed-uniforming cylinder diameter was 6 mm. Verified by field experiments, the Astragalus smicus emergence rate was 95.87%, quantity consistency was 12.7%, coefficient of variation of sowing uniformity was 8.07% in the condition of optimal parameter combination, the relative error was below 3% compared with optimal values predicted by the model. Compared with the existing sowing methods of Astragalus smicus, working efficiency of the designed ditching and sowing machine was 1 hm2/h, which was superior to the artificial sowding working efficiency of 0.1 to 0.125 hm2/h, the hand-shaking working efficiency of 0.2 to 0.3 hm2/h and the motorized sowing working efficiency of 0.5 to 0. 8 hm2/h, and was lower than the UAV sowing working efficiency of 3 to 4 hm2/h. In addition, the coefficient of variation of sowing uniformity and the combination type of ditching and sowing machine were also significantly superior to that of other methods. The Astragalus smicus ditching and sowing machine developed in the paper integrated ditching and sowing links in one operation, the working efficiency was greatly improved, the research provided a new method for Astragalus smicus ditching and sowing machine for machine-harvested rice stubble field. [ABSTRACT FROM AUTHOR]

Small deep-cultivators with light weight and simple structure are urgently needed to satisfy the requirements of deep cultivating in hilly regions. Development of a low power-consumption rotavator is a prerequisite for the lightweight of a small deep-cultivator. In this paper, in order to reduce the power consumption of the rotavator for a small vertical-shaft deep-cultivator, a multi-helical rotavator was proposed. The multi-helical rotavator consisted of a vertical-shaft rotavator head and 3 discontinuous multi-helical cutters that are unevenly distributed along the circumference of the head. The discontinuous multi-helical cutter consisted of a cutter-shaft and 3 discontinuous helical cutter edges that are evenly distributed along the axis of the cutter-shaft. The rotavator head had a diameter of 250 mm and the rotavator had a design tillage depth of 30 cm. The cutter-shaft length was 0.35 m and the helical angle of the helical cutter edge was 53º. Based on the motion analysis of the multi-helical rotavator, the motion path and its parameters model were established. The structure and operating parameters of the discontinuous multi-helical cutter and the rotavator were designed and analysed. Then the three-dimensional models of the discontinuous multi-helical cutter and the rotavator were established for simulation analysis. Based on the SPH (smoothed particle hydrodynamics) algorithm, the motion of soil particles, cutting resistance and power consumption were simulated and analysed during the operation of the discontinuous helical cutter and the traditional vertical-shaft orthogonal cutter in ANSYS LS-DYNA. In addition, an actual multi-helical rotavator was manufactured and its tillage effect and power consumption were tested. The simulation results showed that, comparing with the traditional vertical-shaft orthogonal cutter, the performance of the discontinuous helical cutter was significantly improved. 1) The discontinuous multi-helical cutter could greatly stir the upper soil particles, and the displacement of the upper soil particles was obviously increased during the cultivation process. At the same time, the lower soil particles were only slightly disturbed, and the displacement of the lower soil particles was significantly reduced. 2) The cutting resistance of the designed discontinuous helical cutter decreased by an average of 37.5%. Besides, the fluctuation range of cutting resistance decreased by an average of 60.6%, which could reduce the rotavator vibration and make the small deep-cultivator to work more stably and more reliable. 3) The total energy consumption of the designed discontinuous helical cutter was reduced by 58.7% and the average power consumption was reduced by 47.6%, which could reduce the weight of the small deep-cultivator under the same power consumption conditions. The test results showed that the actual power consumption of the designed multi-helical rotavator was 2.86 kW, which was 11.28% higher than the simulation value of 2.57 kW. The simulated power consumption value was close to the test value, which verifies the validity of the simulation results. At the same time, the average tillage depth of the designed multi-helical rotavator was 28.7 cm with a stability coefficient of 94.64% and the average soil pulverizing rate is 76.02%. Therefore, the designed multi-helical rotavator had better crushing and throwing ability than the traditional vertical-shaft orthogonal cutter, and could improve the soil subsoiling effect while meeting the requirement of the tillage depth. The reduction in cutting resistance and the decrease in cutting resistance fluctuation could also reduce the power consumption and vibration of small deep-cultivators. [ABSTRACT FROM AUTHOR]

The purpose of conservation tillage is to protect soil structure, conserve water and maintain soil moisture. No-tillage sowing is the core of the development of conservation tillage technology. Focusing on many problems unsolved of no-tillage planter, such as the non-adjustable space between seeds, seeding only on a single line, high probability to be adhered and blocked, and poor adaptability, this paper proposes a new advanced design of no-tillage hill seeder. The hill seeder is connected to tractor with the suspension frame, and it can complete a seeding of three rows by three planting units at every run. Each planting unit is mainly composed of land wheel, seed metering device, fertilizer apparatus and 45° inclined inserted digging implement. The digging implement is mainly composed of parallel four-bar mechanism, slider-crank mechanism and cam mechanism. The power transmission route is as follows: the land wheel rotates to obtain power, drives the seed metering device and fertilizer apparatus, and then through the chain drive to the parallel four-bar mechanism and slider-crank mechanism, completing penetration reciprocating seeding and fertilizer, while driving cam mechanism controls the opening and closing movement of the duckbill. The design of no-tillage hill seeder has the following features. Firstly, to efficiently avoid the problems of soil blocking, soil attaching, difficulties in opening and so on, this new hill seeder would perform an insertion into soil at a 45°angle with a refined plugging unit. Secondly, this design has added configurable sprocket gears to solve the problem that the existing seeders could not adjust the distance between seeds. Thirdly, the design of the parallel four-bar mechanism makes the insertion of the crank blocks more smoothly with the unified seeding depths, at the same time the synchronization of seeding and fertilizer could be achieved. Additionally, all the parameters of the machine (e.g. rows spacing, plants spacing, seeding depth, fertilizer depth) are adjustable which could bring better adaptability. Field experiment was done in the experiment base by inclined inserted no-tillage hill seeder prototype. The results showed that seeding depth and fertilizer depth qualified rates were 90.52% and 91.23%, qualified rates of horizontal distance and vertical distance between seed and fertilizer were 95.71% and 91.65%, qualified rate of seeding uniformity is 92.13%, replay rate of seeding uniformity is 4.60% and leakage rate of seeding uniformity is 3.27%. The data are superior to the standard value, which is 85%, 15% and 8%. The research can provide a reference for the design of no tillage planter. [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]

Garlic is one of the major cash crops in China, and it is mainly distributed in Shandong, Henan and Jiangsu Provinces. Single grain sowing is crucial for garlic planting, it needs to follow the agronomic requirements of root down and scaly bud upward, and therefore garlic planting mainly uses artificial means, but this method has shortcomings of strong labor intensity and low efficiency. Correspondingly, some developed countries like America and Korea have realized garlic planting mechanization in 1950-1960s, which have extensive arable land and indefinite requirement of garlic scaly bud direction when planting, and thus foreign garlic planting machinery is not suited to China’s national conditions. In recent years, the garlic planter is developed towards automation and intelligence. However, existing garlic planter is hard to distinguish the direction of garlic scaly bud, and it also has complex structure and low efficiency. The scaly bud direction distinguishing is a core technology of garlic planter, and it is also the most difficult technical operation. Therefore, how to ensure direction of the garlic seed scaly bud in the process of planting has been a key technical problem of garlic planter. According to present condition, a full-automatic extraction and release device of garlic seed box was designed based on garlic seed box method, and it can automatically track driving according to the travel speed of machine. The full-automatic extraction and release device of garlic seed box consists of drive system, conveying device, extraction and release device, speed encoder, photoelectric sensor and MCU (micro-controller unit) system. The drive system consists of stepper motor, sprocket and chain, and it has 2 parts, and one provides transmission power for the whole machine walking, and the other controls conveying device working. The conveying device consists of conveying belt, roll shaft and bearing housing, the conveying belt is transversely mounted on the frame through roll shaft and bearing housing, and its working state is controlled by MCU system. The conveying device mainly carries out transverse transportation of garlic seed boxes. The extraction and release device consists of steering wheel, central actuator, mechanical arm, auxiliary actuator and manipulator, among which the manipulator consists of U shape rotating frame, L shape mounting panel, distance controlling actuator, special shaped gear disk, connecting rod, connecting arm and claws, and it mainly realizes the functions of garlic seed boxes precision capture, smooth traffic and seamless release. The velocity measurement encoder is used for detecting unit movement speed, and provides speed messages to central actuator and distance controlling actuator. The photoelectric sensor is used to detect whether the garlic box is in place. The garlic seed box planting method reduces the damage of garlic seed and improves work efficiency, and solves the problem of the direction of garlic seed. This paper designed mechanical arm and manipulator, the mathematical model of each key component was established through the theory analysis, and thus the structure and working parameters of mechanical arm and manipulator were determined. At the same time, the influence rule of the speed of device marching on operation parameters of mechanical arm and manipulator was proved, and the influencing factors of the clearance of adjacent garlic seed boxes were specified. The test was carried out for testing the influence of the speed of device marching on the clearance of adjacent garlic seed boxes after they were released. The results showed that when the speed of marching is 0.90 km/h, and the speeds of central actuator, auxiliary actuator and distance controlling actuator are 26.04, 26.04, and 13.89 r/min, respectively, the clearance of adjacent garlic seed boxes is less, which is 5.6 mm, and the release effect is better. The machine has better stability and release effect, and work efficiency of device has been improved obviously. The research results can provide reference for realizing automation of garlic planting. [ABSTRACT FROM AUTHOR]