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Modern mechanical equipment is very important to agricultural production. The introduction of modern machinery and equipment into the production process of traditional Chinese medicine is an effective way to solve the contradiction between the expansion of production scale of traditional Chinese medicine industry and the reduction of labor force. The mechanization development of traditional Chinese medicinal materials production is in the initial stage. The main goal at this stage is to realize the "from scratch" of the relevant technical equipments. However, due to the varieties of traditional Chinese medicine, complex production process, regional differences and other factors, it is difficult to judge the demand for mechanized production of traditional Chinese medicine and lack of methods. How to evaluate and analyze the the differences in the demand for mechanized development is of great significance to the research of technical equipment, the implementation of supply side reform and the promotion of the production and development of traditional Chinese medicine. According to the characteristics of traditional Chinese medicinal materials production, combined with the analysis of degree of mechanized operation, status of technology and equipment and levels of user demand, this paper constructs the evaluation index system for the development of technical and equipment of traditional Chinese medicinal materials production. The degree of mechanized operation indicates the ratio of mechanized operation area to the total planting area. The status of technology and equipment is alculated by weighting the five indexes of advance ment, economy, applicability, reliability and security. The levels of user demand is divided according to the proportion of users with demand, users with demand but no machinery available and the proportion of users with demand in different production process. Then an evaluation model combined with entropy weight method and hierarchical cluster analysis method is formed, and after classifying by the hierarchical cluster analysis method, the model is expressed functionally based on the Fisher discriminant method. In empirical research, the demonstration base of national comprehensive experimental station of traditional Chinese medicinal materials is selected as the research object, eight production processes of sowing, transplanting, fertilization, intertillage, plant protection, harvesting, cleaning and drying are selected for evaluation Through the investigation in 23 provinces of China, the production processes of traditional Chinese medicinal materials production are categorized into three types. The harvest, intertillage, and transplanting belonged to the type A, which have the highest demand level. The seeding is classified as type B, and the drying, cleaning, plants protection and fertilization are type C. The phenomenons of “no machinery available” and “unsuitable to use” are obvious for type A, and there is an urgent demand for the development of technology and equipment, the evaluation results are consistent with the investigation results. According to the further calculation results based on discriminant Function I, the central values of type A, type B and type C are -2.868, 1.904 and 1.675 respectively, which shows that the evaluation model of development demands classification can be accurately expressed by quantitative mathematical functions. The machinery of the type A production processes represented by harvest should be developed in priority in traditional Chinese medicinal materials production. The research and development of special machinery for the production of traditional Chinese medicinal materials should take the road of combining independent innovation research with the introduction of other main grain production machinery. The model proposed in this paper reflects the reasons and details at the same time of forming classification, which can provide reference for the development demand evaluation of other crops or regional agricultural machinery technology and equipment with backward mechanization development. [ABSTRACT FROM AUTHOR]

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]

Depth estimation is critical to 3D reconstruction and object location in intelligent agricultural machinery vision system, and a common method in it is stereo matching. Traditional stereo matching method used low-quality image extracted manually. Because the color and texture in the image of field plant is nonuniform, the artificial features in the image are poorly distinguishable and mismatching could occur as a result. This would compromise the accuracy of the depth of the map. While the supervised learning-based convolution neural network (CNN) is able to estimate the depth of each pixel in plant image directly, it is expensive to annotate the depth data. In this paper, we present a depth estimation model based on the self-supervised learning to phenotype tomato canopy. The tasks of the depth estimation method were to reconstruct the image. The dense disparity maps were estimated indirectly using the rectified stereo pair of images as the network input, from which a bilinear interpolation was used to sample the input images to reconstruct the warping images. We developed three channel wise group convolutional (CWGC) modules, including the dimension invariable convolution module, the down-sampling convolution module and the up-sampling convolution module, and used them to construct the convolutional auto-encoder - a key infrastructure in the depth estimation method. Considering the shortage of manual features for comparing image similarity, we used the loss in image convolutional feature similarity as one objective of the network training. A CWGC-based CNN classification network (CWGCNet) was developed to extract the low-level features automatically. In addition to the loss in image convolutional feature similarity, we also considered the whole training loss, which include the image appearance matching loss, disparity smoothness loss and left-right disparity consistency loss. A stereo pair of images of tomato was sampled using a binocular camera in a greenhouse. After epipolar rectification, the pair of images was constructed for training and testing of the depth estimation model. Using the Microsoft Cognitive Toolkit (CNTK), the CWGCNet and the depth estimation network of the tomato images were calculated using Python. Both training and testing experiments were conducted in a computer with a Tesla K40c GPU (graphics processing unit). The results showed that the shallow convolutional layer of the CWGCNet successfully extracted the low-level multiformity image features to calculate the loss in image convolutional feature similarity. The convolutional auto-encoder developed in this paper was able to significantly improve the disparity map estimated by the depth estimation model. The loss function in image convolutional feature similarity had a remarkable effect on accuracy of the image depth. The accuracy of the disparity map estimated by the model increased with the number of convolution modules for calculating the loss in convolutional feature similarity. When sampled within 9.0 m, the root means square error (RMSE) and the mean absolute error (MAE) of the corner distance estimated by the model were less than 2.5 cm and 1.8 cm, respectively, while when sampled within 3.0m, the associated errors were less than 0.7cm and 0.5cm, respectively. The coefficient of determination (R²) of the proposed model was 0.8081, and the test speed was 28 fps (frames per second). Compared with the existing models, the proposed model reduced the RMSE and MAE by 33.1% and 35.6% respectively, while increased calculation speed by 52.2%. [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]

With the steady progress of China's agricultural modernization, broad demands of agricultural machinery for production are growing extensively. Agricultural unmanned aerial vehicles (UAVs), an important part of agricultural aircraft, have become a new force in the field of China Precision Agricultural Aviation. Used in agricultural areas where ground-based machinery has difficulty in cultivating, agricultural UAVs have shown obvious characteristics and advantages in farming, application and popularization. With the further development of precision agricultural aviation technology, one of the inevitable trends of intelligent development is to realize the autonomous identification of obstacles and real-time obstacle avoidance for agricultural UAVs. The ideal obstacle avoidance system can automatically and promptly avoid all kinds of obstacles in the flight path, avoiding accidents due to operational errors, failures of autonomous flight or other unexpected failures. Thus, it can effectively reduce unnecessary loss of property and casualties. However, the complex operating environment of farmland and the changing types of obstacles both increase the complexity of obstacle avoidance research. When operating during the outbreak of pests, at night or in an environmental with low visibility, many factors will limit the work efficiency and increase the risk of crash if the UAVs mainly rely on pilots to observe and make judgement. Therefore, much progress needs to be made to realize real-time obstacle avoidance of agricultural UAVs. To improve the safety of aviation operations, in this paper, we classified the farmland obstacles in two ways and puts forward the obstacle avoidance zone and related avoidance tactics. The distance between obstacles and the movement of agricultural UAVs was relative. However, the obstacle avoidance zone of its main field of view was fixed and absolute. In execution area (<5 m), the obstacle avoidance motion commands shall be executed to avoid short-range obstacles. In warning region (5-15 m), early warning shall be automatically performed on the medium-long-distance obstacles, and follow-up shall be carried out to prevent unexpected accidents. The obstacles in safe region (>15 m) can be ignored temporarily until they entered the warning region, then it should start the obstacle avoidance pretreatment. Because large, small and medium-sized obstacles had obvious features, they can be totally or partially detected by obstacle avoidance sensors in the safe area. When entering the warning area or execution area, it was relatively easy for drones to avoid them. As for micro and visually-distorting obstacles, it was difficult to identify and evade them even when they got into the warning and execution areas. At present, apart from improper manual operation or sudden failure of the machine, the main reason for most UAV crash accident was obstacle avoidance failure, such as failing to avoid wires, branches and other tiny obstacles. Although the rate of crash accidents caused by tiny obstacles was relatively low, the property loss rate and the casualty rate were extremely high. Therefore, how to avoid tiny obstacles should be the priority of agricultural UAV obstacle avoidance research. Through comparative analysis of domestic and foreign application situation of agricultural UAV obstacle avoidance technology and various obstacle avoidance sensors, in this paper, we analyzed the deficiency of China's agricultural UAV obstacle avoidance problem. With the further development of precision agricultural aviation technology, avoidance system with multi-sensor fusion would become the mainstream of real-time obstacle avoidance system for agricultural UAVs. The combination of visual and non-visual sensors provided a variety of possibilities for the implementation of autonomous spraying and intelligent navigation. Finally, in this paper, we proposed several forecasts to the UAV obstacle avoidance system construction, including development of real-time active obstacle avoidance technology, the agricultural UAV obstacle avoidance process and an obstacle avoidance method to identify the substitutes of tiny obstructions, in order to provide a reference for the orderly development of agricultural UAV's obstacle avoidance technology in China. [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]

Considering the rapeseed planting area is large in hilly and montanic area and the planting period for rice and rapeseed is partly overlapped in flat area in China, a rapeseed aerial seeding device used for UAV was designed in this paper. The rapeseed aerial seeding device included two parts: seeding device and control system. The working power come from UAV. Structure parameters of seed box volume, seed-filling funnel and geneva wheel of aerial seeding device were confirmed. The volume of seed box was 5.2 L so that it provided enough rapeseed for UAV to seeding 0.67 hm2 area at one operation. The upper inlet shape of seed-filling funnel was a rectangle with length 30 mm and width 18 mm. The down outlet shape of seed-filling funnel was a circle with diameter 15 mm. The length of seed-filling funnel was 49-65 mm. The diameter of geneva wheel seed metering device was 80 mm with 30 type holes per circle in circumferential direction. Aerial seeding control system contained hand tele-control system and airborne tele-control system. The airborne tele-control system contained main controller (STM32 single chip), BeiDou Navigation chip, piezoelectric sensor, stepping motor with driver, flying information detection module, wireless transmission module and power module. The hand tele-control system contained controller, display screen, wireless transmission module, power module and keys. When the UAV was in the working field, the location information of UVA was detected by flying information detection module and the aerial seeding device started to seeding. The aerial seeding device stopped to seed when the flying information detection module detected that the UAV was out the working field. Hand tele-control system communicated with the airborne tele-control system acquired the flying information and then controlled the seeding rate of metering device when the UAV was flying. In order to analyze the factors affecting the working performance of aerial seeding device, the simulation model of airflow field of UAV rotor wing was established and the effects of rotor wing to airflow field was analyzed. The simulation results showed that the airflow field conducted by rotor wing affected the rapeseed falling track obviously. With the flight height of UVA increased, the range of space airflow field affected by UVA wings increased, and the distribution area of rapeseed landing on the ground increased. The relationship model between the UAV flight speed and geneva wheel rotary speed was established by selecting the length of seed-filling funnel and geneva wheel rotary speed as the factors based on the bench est. The results showed that when the distance between outlets of seed guiding tube and rotor wing was 300 mm, the length of seed-filling funnel was 53 mm, geneva wheel rotary speed was 10-50 r/min, the geneva wheel seeding rate met the requirements at the UAV flight speed of 2-4 m/s. The pavement test was conducted and the results showed that the effective working width was 2.15-2.45 m, coefficient of variation of seed distribution uniform was 32.05%-34.78% at the cross distance of seed tube outlets of 1.1 m, UAV flight height of 2-2.5 m. The average seedling density of field experiment was 64.5 plants/m², the coefficient of variation of seed distribution uniformity was 38.23%, which meet the requirements of rape cultivation This study can provide a reference for the design of UAV aerial seeding device. In order to further optimize the working performance of UAV aerial seeding, it is necessary to conduct comprehensive tests under natural wind and different field conditions in the future research work. [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]

Frictionless magnetic bearings can contribute to modern agricultural equipment, such as pump, fan and blast, thereby to achieve high efficiency, energy-saving and long-term reliable operation. But magnetic bearings are confined to the configuration and price of position sensors. In the recent years, the self-sensing and sensor less mode have been developed to extend the application of the magnetic bearings. Most previous studies are focused on the estimation algorithms, such as the state observer approach and parameter estimation approach. Moreover, the extra phase-shift is introduced by the estimator which consists of the analogue filter or FIR or more complex mathematic algorithm. The self-sensing path turns complex and longer due to the fundmental ripple needs to be extracted, amplified and filtered. Therefore, the key research target of this paper is the operation of position estimation. An absolute mathermatical approach was proposed to extract the rotor positon using the zero ripple characteristic based on the cosine-function of coil current. A self-sensing algorithm based on SS-DCE (Synchronous-Sampling-based Discrete Current Estimator) can be used to remove the extra phase that introduced by the analog or digital filters of the sensing path. Synchronous-sampling technique was used to sample the coil working current in the estimator due to PWM switching harmonics without the discrete current. Moreover, the phase shift can be minimized in SS-DCE scheme because the filters of amplitude demodulation have been eliminated, and the configure of AMBs are simplified. The numerical results of SS-DCE were also compare with that of the digital filtering amplitude demodulation approach(DFAdM). The test results of the position estimators showed that the optimal performances can be obtained, when the switching frequency and synchronous sampling frequency are 2 kHz, control frequency is 50 Hz, sampling frequency of DFAdM is 100 kHz, and some electrical conditions as the bias current 3.0 A, nominal inductance 13.2 mH and power supply 50 V. The SS-DCE was also verified by the simulation in 1-DOF AMBs. The static performance evalution was performed on the proposed estimator, indicating that the precision of SS-DCE was about 2.72%, and the absolute error was 5.43 μm in the position range of 50-250 μm. The precision of DFAdM estimator was 4.85% and the absolute error was 9.71 μm. Frequency response analysis was used to evaluate the dynamics performance in open loop state, indicating 158° phase margin at the eigen frequency 19.26Hz. Moreover, a rig of self-sensing AMBs was setup with TMS320F2812, LEM HX-05, PM10CJS060 and micro-positioning platform. The precision of SS-DCE was about 2.53% referring to eddy current sensor HZ-891. SS-DCE-based rotor showed good stability, rapid convergence and acceptable overshot under pulse disturbances that applied through a direct knock on the truss by a rubber hammer. The proposed approach can provide a direct guidance for the active control of magnetic levitation, magnetic damper and other engineering fields. The influence of PWM duty-cycle and low SNR on magnetic bearings can be performed in the near future research works, thereby to enhance the application of magnetic bearings for modern agriculture. [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]

In recent years, the Somatosensory Technology has been applied in many fields including entertainment, education, automation and medicine etc. But in agriculture, it still has rarely involved. The traditional human-computer interaction system of virtual plant operating at a particular operating system or on a mobile platform, and interactive mode is interactive through the mouse and keyboard, need parameters and commands more cumbersome user input, resulting in the lack of good user interaction experience. In view of the above situation, in this paper, we designed and developed virtual farming object interaction system based on cloud computing and somatosensory interactive technology. The system firstly generated a 3D model of the virtual crop in the cloud, and the model was stored in the cloud. Our virtual crop model included rice and tomato. The cloud-side provided the data calculation ability and responded the browser requesting, the browser-side was responsible for display, caching and a small amount of calculation, and Leap Motion was responsible for interaction on the browser-side. In order to obtain the relevant parameters for rice modeling, we had done experiments in China National Rice Research Institute in Zhejiang, Hangzhou between 2015 and 2016. The selected rice stage was from the jointing stage to the heading stage. For each plant, we measured three blades in different leaf positions, which included blade lengths, blade widths, the changed widths along the blades, and blade growth positions. The 3D data of virtual crops needed to be generated by algorithms on Amazon cloud platform. The topological structures of tomato plants were described by the parametric L-system in our system, and we separated the structures into stems, rachis, blades, fruit branches and flower branches. Using WebGL to render 3D crop models on browser allowed and incorporated users to directly interact with it. In this paper, we defined a 3D virtual crop data exchange protocol, which supported crop species selection, morphological changes, crop growth, pause, shrinkage, and shadow generations. When the Leap Motion received a gesture signal, users can select crop specie, and then the server would generate the corresponding 3D crop data, including geometry, color and texture information, and returned it to browser in JSON format. We built a one-hand and a two-hand gesture base, and each gesture can realize the free interaction of 3D models. Users can freely switch between one-hand mode and two-hand mode. The interactive system of virtual crops based on Motion Leap was composed of the server and the browser. It achieved the translation, rotation, plant growth, morphological changes and 3D model update operation. Our hardware environment was: 1) quad-core Intel CPU 2.4 GHz, 8 G of RAM on the server-side; 2) Windows 7, quad-core CPU 2.6 GHz, 4 G of RAM, 2 GB NVIDIA GeForce GTX 860 M+Intel HD 4 600 on the browser-side. The system had been implemented in WebGL and JavaScript and effectively running on the major browsers including Firefox, Chrome and IE. Experimental results showed that the users can control the shape and growth of the virtual crop model in real time by using different gestures in the browser, from which they had a good interactive experience. The establishment of the system can provide a technical reference for similar research. [ABSTRACT FROM AUTHOR]

The quality of seedbed after seeding such as soil surface leveling, soil-breaking rate and seed furrow preparing and so on, are the main factors affecting the seedling rate of rapeseed. A good seedbed is a necessary condition for uniform seedling emergence, increasing the rate of subsequent seedlings and promoting the homogeneity of plants after sowing. In view of the fact that the measurement and data processing methods of rapeseed seedbed surface roughness under mechanized direct seeding cannot fully reflect the real soil surface condition, a method of measuring and quantifying roughness surface area by using laser radar scanning technology is proposed in this paper. The main components of the measuring device are the lidar, linear guide, stepper motor, portable computer and other components. The device can quickly acquire soil surface data in three dimensions through the whole working width of direct seeding machine. The surface roughness data of rapeseed combined direct seeder and no-tillage direct seeder after operation were used to detect the effect of two kinds of seedbed operation on seedbed surface. The characteristics of rapeseed direct seeding process were analyzed, three-dimensional digital modeling and detrend processing of ground data after two kinds of direct seeders were carried out by using MATLAB. The least square method was utilized to eliminate the inclined tendency of seedbed surface, the fourth order polynomial was applied to remove the slope trend in the width direction of the soil surface of rapeseed combined direct seeder. The root mean square (RMS) height and the correlation length were involved as evaluating parameters to analyze the data. Statistical results of roughness parameters for different spatial sampling intervals and different angles cross-section data showed that the average RMS height and RMS height mean error of 170 mm sampling interval were all higher than that of 5 mm sampling interval, the average RMS height of the 170 mm sampling interval was 2.2 mm higher than that of the 5 mm sampling interval, the corresponding correlation length was around 1.8 times the latter; and the RMS height and the correlation length error of the 170 mm sampling interval were higher than that of the 5 mm sampling interval. The maximum difference of RMS height and correlation length of surface elevation data were 7.69 and 25.14 mm respectively in the three directions of 0, 45 and 90 degrees in the forward direction of vertical unit, and there was obvious anisotropy on the surface of seedbed with structural characteristics such as seed trench. Statistical results of local roughness quantification using sliding sampling windows in different size regions showed that when the window width is 0.5 times the compartment width, the standard deviation of RMS height can be stabilized within 0.27 mm if the length of the window is not less than 1.2 m, and the influence of local surface tilt on the roughness calculation can be eliminated by the trend treatment of the tilt of each sampling window. The results can provide reference for the measurement and quantitative analysis of surface roughness in rape direct seeding operation. [ABSTRACT FROM AUTHOR]

Aiming at the problems of the poor quality of the hole shape formed by the transplanter will cause the seeding to tilt, when watermelon seedlings raised on pie-shaped compression substrate for transplanting. Opener parameters of hole-forming device in semi-automatic transplanter for watermelon seedlings raised on compression substrate is optimized to meet the agronomic requirements of transplanting compression substrate watermelon seedling and combining the characteristics of dryland transplanting machinery. Through analyzing the movement mechanism of the opener, this paper established the parameter equation of the planting hole. It was concluded that the depth of the hole-forming was the main factor affecting the longitudinal length of the upper part of the hole mouth. The Edinburgh Elasto-Plastic Cohesion Model, which can reflect the elastoplasticity and cohesiveness of soil. The simulation analysis of the hole-forming process of the opener was carried out by using the discrete element method. The rationality of the structure parameters and motion parameters of the opener was verified, and the hole-forming effect of different diameters of the small end of opener was explored at different theoretical depth of hole-forming. According to the simulation results, the diameter of the small end of opener was 60 mm and the theoretical depth of hole-forming was 65 mm. The bottom of the hole was relatively flat, effective depth of hole-forming was 51 mm. The upper longitudinal length of hole and the upper width of hole were relatively small. It was conducive to the growth of coated transplanted crops. In order to verify the accuracy of the above design method and the reliability of the operation of the hole-forming device, a prototype and 3 sets of opener with different small end diameters were trial-manufactured to carry out field experiments, and the upper longitudinal length of hole, upper width of hole and effective depth of hole-forming were measured. The results of the experiment combined with the simulation analysis showed that the upper longitudinal length of hole and the upper width of hole were increased with the increase of the theoretical depth of hole-forming. The upper longitudinal length of hole and the upper width of hole increased with the increase of the diameter of the small end of the opener. The influence of the diameter change of the small end of the opener on the upper longitudinal length of hole was weaker than the change of theoretical depth of hole-forming. The theoretical depth of hole-forming had a significant effect on the upper longitudinal length of hole. The larger the diameter of the small end of the opener, the more the upper width of hole increased as the theoretical depth of hole-forming. The minimum error between simulation result and the test result of upper longitudinal length of hole was 0.34%, the maximum was 12.78%, and the average error was 6.7%. The minimum error between the simulation result and test result of the upper width of hole was 7.23%, maximum was 20.87%, and average error was 12.33%. The minimum error between effective depth of hole-forming simulation results and test results was 1.79%, the maximum was 17.92%, and the average error was 10.46%. The research can provide a reference for the optimization and improvement of the opener. [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]

Hexapod robot has the potential to be an important agricultural equipment in hilly areas in the future, but its feature of high energy consumption has become a technical bottleneck in practical application. Energy self-sufficiency may be within our reach if the robot is driven by electric motors and can be charged by solar energy, but this type of robot often has no self-locking joints, which leads to certain energy consumption against gravity even when they stand still; although the joint brake mechanism may be helpful, but shortcomings like energy penalty and lack of compact in mechanism that come with it will appear. If the joints are self-locking to ensure no energy consumption when the robot stands still, then the energy consumption when moving will increase dramatically. Based on the above problems, to minimize overall energy consumption of the robot when it's moving or long-time standing still, a hexapod robot design with optimal disposition of self-locking joints was given, the energy consumption optimization model was also built only considering that the robot had a specific motion which avoided a non-deterministic polynomial hard problem, and thus the model just needed to optimize the energy consumption instantaneously. A defect of such an existing optimization model based on the torque distribution algorithm was corrected by introducing the difference of torque transmission efficiencies of robot joints in forward and reverse drive; in order to adapt the compacted soil ground in hilly areas, the constraints of the existing model which were suitable for the rigid environment were modified based on terrain mechanics. For different self-locking joints configurations, there would be different energy consumption optimization models, and their corresponding objective functions were given separately; this allowed energy consumption comparison of different configurations being conducted based on the minimum values of objective functions from different optimization models, and then the self-locking joints must be positioned properly and used as few as possible in the optimal configuration. In order to validate the optimization models and the effect of optimal disposition of self-locking joints, an experiment and optimization simulations were carried out. Torque transmission efficiencies of a self-locking worm joint in forward and reverse drive were tested in the experiment. The test data agreed with the ones obtained from the theoretical formula, which proved the correctness for the model to introduce the difference of torque transmission efficiency and the accurateness of the model compared with the existing one. Optimization results of the model proposed in this paper were contrasted with that of the existing one through Matlab and Adams co-simulation. Comparison results show that: joint torques as the optimum solution obtained from the optimization model of this paper have fewer chances to do negative work when robot is moving, which is better in accord with the "gravitationally decoupled actuation" and "coupled drive" concepts, and thus the total energy consumption of robot can be further reduced by more than 40% compared with the existing model. For a given robot configuration, the power consumption is more than 38 W when standing still if the robot has no self-locking joints, and the energy consumption when moving is 3 times higher than the former one if all the joints are self-locking; only when applying the optimization model and the optimal joints disposition, the robot can not only stand still with no energy consumption but also consume energy basically at the same level as the former one when moving, and the energy consumption of the robot is only 14.2%, 45.5% and 16.3% higher than that with no self-locking joints when walking downhill, uphill along a 30° ramp and level, respectively. The energy consumption optimization model proposed in the paper provides theoretical supports for the design and optimization of agricultural hexapod robot with self-locking joints. [ABSTRACT FROM AUTHOR]

Working in harsh environments and bumpy roads, ground vehicles such as the agricultural vehicle and construction machinery often suffer from random load which may obey different load distributions. Aiming at the problem that the single distribution is difficult to fit the multi-peak form of the load, the traditional load spectrum compiling method is improved to obtain the load spectrum that reflects actual working conditions. During the field test of wheel loader, the semi-axle load data, the speed and the bucket cylinder displacement are collected through sensors and data acquisition system. The operation modes of wheel loader can be reflected by the above data. Then the semi-axle load data are divided into 6 sections according to the operation modes of wheel loader. The 6 sections are no load forward section, spading section, full load backward section, full load forward section, unloading section and no load backward section. The load mean, load amplitude and their corresponding frequency are obtained after conducting rain-flow counting for each section. Both the single distribution and the mixed distribution are applied to fit the load mean and load amplitude in each section. The maximum likelihood estimation method is used for single distribution estimation, and the maximum expectation algorithm is used for mixed distribution estimation. The log-likelihood function values and decision coefficients are applied to the fitting test. The larger the log-likelihood function value and the decision coefficients, the better the fitting results. The fitting test results show that the fitting effects of the mixed distribution for both load mean and load amplitude are better than those of the single distribution in no load forward section, spading section, full load backward section, unloading section and no load backward section. The decision coefficients of the mixed distribution for load mean are 32%, 2.3%, 25.1%, 40.1% and 160.8% respectively larger than the corresponding decision coefficients of the single distribution. The decision coefficients of the mixed distribution for load amplitude are 8.3%, 6.7%, 1.4%, 6.2% and 1.2% respectively larger than the corresponding decision coefficients of the single distribution. For the load mean in full load forward section, the corresponding fitting test values of the mixed distribution are larger than those of the single distribution, which shows the fitting effect of the mixed distribution is better. Different conclusions are obtained for the load amplitude in the full load forward section. The fitting test values of the load amplitude are .1 417.10 and 0.995 9 for the single distribution, while .143 0.50 and 0.962 2 for the corresponding mixed distribution. The above values show that the fitting effects of the single Weibull distribution with the parameters of (8.717 1, 0.887 1, 9.344 1) for the load amplitude are better. It is clear to demonstrate that the load data of different sections may present different characteristics and obey different distributions. Furthermore, the load spectrum can be affected by the fitting effect caused by the distribution type according to the compiling procedure. In this paper, the load spectrum compiling method is improved. The comparisons of fitting effects of different distributions are added before deciding the distribution function. Based on the distribution which has good fitting effects in each section, the maximum values of the load mean and load amplitude of each section are determined. The joint probability density functions are also obtained. Then the frequency extrapolation and synthesis are carried out. Next the two-dimensional load spectrum is obtained. According to the Goodman theory and the fatigue damage theory, the two-dimensional load spectrum is converted into a one-dimensional load spectrum with load mean of 0. The proposed method is helpful to solve the problem of fitting multi-peak form of the load and contributes to compile the load spectrum that reflects actual semi-axle load conditions of wheel loader. [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]

In recent years, to meet the development requirements of green production and energy efficiency of modern agriculture, the closed-center load-sensing hydraulic system has been widely used in the domestic and overseas agricultural machinery because of its low energy consumption and strong adaptability. As a key power component of the hydraulic system of the modern agricultural equipment, the performance of the load-sensing variable pump plays an important role in the performance of the whole hydraulic system. At present, the domestic scholars have mainly concentrated in the optimization and characteristics analysis of hydraulic valve, while have done little about the hydraulic pump. Therefore, this paper focused on the mathematical modeling, performance simulation and testing of the load-sensing variable pump, which was composed of swashplate piston pump, plunger cylinder, pressure control valve, flow control valve, load feedback check valve, and so on. In order to better analyze the performance of the pump, the mathematical models of these parts were established by using the pressure-flow equation, flow continuity equation, force balance equation, and so on. Taking into account the effective travel range of the moving parts such as valve spool and swashplate, the nonlinear mathematical model of the load-sensing variable pump based on the boundary conditions was constructed by using the state space method. Then, the simulation model of the pump was established using MATLAB/Simulink based on the mathematical model. By using the fourth order Runge-Kutta algorithm, the steady-state and dynamic performances of the pump were simulated. At the steady state, the compensating pressure of the variable pump was about 1.6 MPa. And in the dynamic state, the outlet pressure and swashplate angle of the pump could respectively follow the step changes of the load and system flow very well, the adjustment time of which was about 0.4 and 0.5 s, respectively. The simulation results showed that the load-sensing variable pump could adjust the inclination angle of the swashplate in real time according to the required flow and pressure of the load, and thus had a good pressure-flow compensation characteristic. Finally, to verify the correctness of the mathematical model and the simulation analysis, an indoor test platform of the load-sensing hydraulic system was built, including hydraulic pump station, proportional control valve, proportional relief valve, flowmeter, pressure sensor, and so on. The dynamic performance test of the load-sensing variable pump was carried out by using the platform. Among them, the step change of the load pressure could be achieved by controlling the proportional valve’s opening pressure, while the step change in flow could be achieved by controlling the spool opening of the proportional relief valve. The test results showed that the load-sensitive pump could output its required flow when the proportional valve spool encountered a step change. And when the load made a step change, the outlet pressure of the variable pump changed almost synchronously with the load pressure. Compared with the simulation results, the steady-state error of the compensation pressure was about 0.1 MPa, which verified the correctness of the nonlinear mathematical model of the load-sensing variable pump. It can be seen that the output flow and pressure of the load-sensing variable pump can be adapted to the load in real time, thus effectively improving the efficiency of the hydraulic system and reducing the system heat, which meets the field work demands of the modern agricultural equipment operation unit. [ABSTRACT FROM AUTHOR]

Overlapped apples are common in natural scenes, and they can seriously affect the execution of picking task. Accurate segmentation of overlapped apples is one of the key problems that picking robot must solve. As the existing overlapped apples segmentation methods could not retain the contour of overlapped parts, a new method of segmenting overlapped apples was proposed in this paper. The steps of the algorithm were as follows: Firstly, the image was processed with morphological opening operation using disk-shaped structural element with the radius of 5 pixels so as to ensure the data information consistent in small area and to make the image more smooth. In order to distinguish the target and the background automatically, the image was then transformed from RGB color space into L*a*b color space. Then -means clustering method was used to segment images to extract apple region. Secondly, in order to extract accurate and entire contour of apple region and keep the contour of overlapped part simultaneously, Normalized Cut (Ncut) method was adopted. To ensure the accuracy of Ncut algorithm, the cluster number was chosen as 5. Thirdly, contour segmentation method was used to extract contour of each apple. The procedures of contour segmentation method were as follows: 1) The extracted contours were connected by simply using eroding operation in order to avoid disconnection at intersection of contours of 2 adjacent apples; 2) Refine the connected contour and search three cross point, then break off the contour at three cross point by assigning zero at three cross point, and 3 contours could be got; 3) Add the 2 contours whose bending directions were opposite, and this was the contour of unblocked apple and the other contour was the contour of blocked apple. Lastly, Spline interpolation method was used to reconstruct the contour of blocked apples. In order to verify the validity of this algorithm, 20 images of adjacent apples were used to conduct the experiment, and the result was compared with the comparison method. The comparison method is a method that uses the connection line of 2 concave points to segment overlapped apples, and then utilizes the Hough transform method to reconstruct the contour of apples. The experimental results showed that for unblocked apples in apple images, average segmentation error of the presented method was 3.15%, 7.73% less than that of comparison method (10.88%). Average overlap ratio of the presented method was 96.08% and was increased by 9.71% compared to comparison method (90.85%). In addition, this method could keep the complete contour information of unblocked apples and thus improved segmentation accuracy effectively. For blocked apples, average segmentation error and average overlap ratio were 5.24% and 93.81%, respectively. The segmentation error was decreased by 11.35% and average overlap ratio was increased by 12.74% compared to comparison method, which indicated that the method could reconstruct contour of blocked apples well. In conclusion, the presented algorithm is feasible to segment and reconstruct 2 overlapped apples without blocking by branches and leaves. However, for the images of overlapped apple blocked by branches and leaves, the images of more than 2 overlapped apples, and the images of 2 overlapped apples unblocked by branches and leaves with unclear contour at overlapped part, this method cannot complete the segmentation, and thus further research would be needed. [ABSTRACT FROM AUTHOR]

The articulated frame steering vehicles (ASV) are widely implemented in agriculture, mining, construction and forestry sectors due to their high maneuverability. The ASVs, however, are known to possess lower dynamic stability and yield high magnitude of whole-body vibration, which are reported to be harmful to the operators. Automatic driving system is thus necessary for the ASVs to exclude the human driver from detrimental operations, especially for the agricultural ASV. In order to enable the automation of ASV, path tracking strategies are essential to maintain the normal work of the vehicles. As the ASV dynamics significantly are different from the conventional vehicles with front wheel steering, the path tracking controller derived for conventional vehicles is considered not to be applicable for the ASVs. Moreover, large variations of the vehicle load and the off-road excisions challenge the robustness of path tracking algorithms. In this paper, a path tracking strategy is proposed for the ASVs on the basis of sliding mode control (SMC). The kinematic model of the ASV is derived neglecting the vehicle dynamics. Three measurable errors are defined to indicate the deviation of real path from reference path, i.e. lateral displacement error, orientation error and curvature error. These errors serve as the inputs in order to synthesize the SMC. The exponential reaching law is selected in order to increase the reaching speed and reduce chattering. The sign function of exponential reaching law is replaced by a continuous function to further suppress the chattering. Lyapunov function is then utilized in order to assess the system stability. The system transition performances in terms of response time, setting time and overshooting are tuned via pole placement method. The differential transformation method is implemented to determine the poles, in order to obtain the transition performances while preserving the system stability. Ackermann's formula is used to improve traditional pole placement algorithm and further design the control law. The open loop eigen-polynomial of the system is thus not requisite. Furthermore, the hardware-in-the-loop (HIL) simulation is conducted to evaluate real-time performance of the proposed control law. The HIL platform is set up on the basis of national instruments PXI-8110 and CRIO-9024 as well as a host computer. The real-time ASV kinematic model established in the MapleSim platform is downloaded into the PXI-8110 as the simulation plant, and the SMC path tracking algorithm compiled by Simulink is embedded to the cRIO-9024 as the real electronic control unit. The host computer couples the real-time vehicle model and the path tracking algorithm via the LabVIEW platform and displays the simulation status as the upper monitor. The path tracking algorithm then controls the vehicle to follow a circle path in real time. The results suggest that the simulated vehicle path is smooth and almost identical to the reference path. The 3 kinds of errors achieve steady state in 10 s. The proposed SMC controller is then demonstrated to be robust even neglecting the vehicle dynamics. The results also suggest that the SMC with Ackermann's formula can fulfill the prescribed request of the dynamic and the steady performance. The real-time performance of the path-tracking is even better than the off-line simulation. The simulation duration 60 s is equal to the calculating duration in the HIL simulation that means the time is synchronous. Compared with the real vehicle test, the HIL simulation is economical and efficient. This research can provide a reference for the design of agricultural ASV automatic driving system. [ABSTRACT FROM AUTHOR]

With the continuous development of industry, environment pollution such as soil acidification and heavy metal pollution of soil becomes increasingly serious, especially in the acidic soil region of southern China. Liming is a traditional and effective method to improve acidic soil. Manual spreading is a kind of traditional method of liming, but it is inefficient and has some side effects like skin damage of workers because of the corrosive property of lime. In order to solve the deficiencies of manual liming and compensate the technology gap of liming machine between domestic and overseas market, we designed a lime spreading machine which was able to be assembled with other agricultural machinery to become combined machine. The development of liming machine has great significance to improve liming efficiency and working conditions. This paper discussed the structure and working principle of the pros spiral lime spreading machine. The machine used the spread roller which was similar to the structure of pros spiral as working parts, used the overlapped waist-shaped hole as the lime spreading outlet, and controlled the waist-shaped hole overlapping area through adjusting assembly to adjust the lime spreading amount. Through experiment we determined the lime outlet size and the lime spreading roller's rotation speed of the lime spreading machine, and experiment results showed that: Firstly, when the lime spreading roller speed was below 125 turn per minute, for the same waist-shaped lime spreading outlet, the lime spreading amount per turn of lime spreading roller could be treated as a constant value, i.e. the spreading amount and lime spread roller's rotation speed were in a linear relationship; Secondly, when the number of lime spreading plate was 40, the hole was waist-shaped hole with the size of 25 mm*10 mm and the rotation speed of the roller was in 120 turn per minute, we got the lime spreading amount of 1 500 kg/h which met the maximum requirements of lime spreading. Considering the linear relationship between the lime spreading amount and the number of lime spreading hole, and the complex conditions after assembled with rotary cultivator, we increased the number of the waist-shaped hole and decreased the rotation speed of lime spreading roller meanwhile kept the lime spreading speed unchanged, and at last determined the lime spreading hole number to be 60 and the roller's rotation speed to be 80 turn per minute as the optimal scheme. We also analyzed the power consumption condition of the lime spreading process and calculated the total power consumption of the working process. Finally, the field test of the lime spreader was carried out, which was conducted in the dry paddy field. Field test results showed that, under the conditions of the lime spreading cultivator at a speed of 5 km per hour, the lime spreading roller at a speed of 80 turn per minute and the overlapping area of the lime spreading hole at maximum size, when the adjusting bar of adjusting mechanism was located in Location XIII, the lime spreading amount reached 1 566.7 kg per hectare. When the adjusting bar of adjusting mechanism were located in Location XII, X and VII, respectively, the lime spreading amounts met the demands of annual lime spreading amount for the first, second and third year, respectively; and when the adjusting bar was at Location II, lime spreading machine almost closed all the lime spreading holes. [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]

Sweet potato is a crop which is drought-resistant, tolerant of poor soil, and owns increasingly enormous potential. It is an important foodstuff, a raw material for starch industry, a kind of health food to prevent cancer and a new raw material for energy as well. The sweet potato planting area in China per year on average is usually 3 667 000 hectares, accounting for 45% of the world's planting area. As sweet potato vines are very long and broomy, the vines must be cleaned up before sweet potatoes are harvested, otherwise are unable to be harvested. Vine crushing and returning machine is usually the dominant form adopted to clean sweet potato vines internationally, but the problems existed in this type of machine were obvious such as low smashing proportion and more stubble residue on the top ridge. New problems have been brought by long stubble such as blocking, larger load and worse smooth working property. Aiming at these problems, the machinery and agronomy should be combined, in order to prove mechanical properties of sweet potato vine and stalk during harvest and working quality of sweet potato vine crushing and returning testing machine. In this paper, the types of fresh purple sweet potato Ningzi 1 and Ningzi 2 in Nanjing, Jiangsu Province were regarded as the tested subject, the electronic universal testing machine, electric drying oven with forced convection, and sweet potato vine crushing and returning testing machine etc. were applied, and the change of moisture percentage and shear strength of sweet potato stalk during harvest were studied. The results showed that at the beginning of experience harvest period, when the percentage of moisture were 81.5% and 78.1%, the shear force were 90.1 and 94.8 N, respectively, during 18 testing days the moisture percentage of sweet potato stalk reduced by 14.8% and 13.97%, respectively, but the shear force of stalk increased by 36.3 and 37.5 N respectively, which showed that the moisture percentage of sweet potato stalk was lower and the shear force was larger as the growth time of plants went on. The internal relations between mechanical crushing quality and percentage of moisture, shear strength were revealed: during the testing period of 18 days, the qualified rates of vine's crushing length for sweet potato type Ningzi 1 and Ningzi 2 dropped by 6.3% and 6.7% respectively, stubble length on top ridge increased by 3.6 and 4.4 cm respectively, which showed that with the increasing of the growth period and the rising of stalk's shear force, the working quality of sweet potato vine crushing and returning machine declined. The quadratic function regression equations on the change between shearing force and moisture percentage of the two types of fresh purple sweet potatoes' stalk were obtained with Matlab when the percentage of moisture was 86.92%-70.08%, and the fitting coefficient of determination R² both reached above 0.99. From the point of increasing the quality of mechanical smashing and mechanical work, it was put forward that the most suitable time of mechanical crushing for the two kinds of purple sweet potatoes during harvest was about 6-8 days, which was a relatively short time. The results offer the direct basis for parameter design of new sweet potato vine crushing and returning testing machine such as machine speed, cutter linear velocity, and also provide the important reference for the selection of suitable harvest period and cultivation agronomic research that fits for machinery operations. [ABSTRACT FROM AUTHOR]