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Generally, revolute joints are considered to be ideal in dynamic analysis of crank- rocker type transplanting mechanism. However, in reality, clearances in revolute joints are unavoidable due to uncertainties such as manufacturing tolerances, assembly errors and wear. When a revolute joint clearance is introduced, the relative position of the axle pin and axle cover is uncertain, which will affect the dynamic responses of the transplanting mechanism. In order to investigate the influence of the revolute joint clearance on the crank-rocker type transplanting mechanism, the dynamic model of the crank- rocker type transplanting mechanism with a revolute joint clearance was established based on the dynamics theory and the Lankarani-Nikravesh contact force model. The revolute joint clearance will introduce 2 extra degrees of freedom, and a stable solution cannot be obtained by solving the dynamic directly, so the dynamic model was solved by the four-order Runge-Kutta method. The parameters of the simulation calculation were obtained according to the actual parameters of transplanting mechanism and literatures. The influence of revolute joint clearance on trajectory, velocity, acceleration and taking seedling position of the needles to take seedlings was analyzed by Matlab. The results showed that the revolute joint clearance had little influence on trajectory, velocity and taking seedling position of the needles to take seedlings, and the revolute joint clearance had great influence on acceleration of the needles to take seedlings; with the increase of revolute joint clearance, the deviation of taking seedling position of transplanting mechanism would be greater, and the amplitude and fluctuation range of acceleration of the needles to take seedlings would increase. In order to quantitatively describe the influence of various revolute joint positions with clearance on acceleration of the needles to take seedlings, the average acceleration was used as the evaluation criterion of the influence. In addition to the revolute joint connected to the drive, the average accelerations of 3 various revolute joints with various clearances were obtained by simulation analysis. For the 3 revolute joint clearances, the revolute joint clearance between the crank and the connecting rod had the greatest influence on acceleration of the needles to take seedlings according to the comparison result of the average accelerations. The continuous contact model was also used to analyze the influence of the revolute joint clearance on acceleration. In order to verify the correctness of the simulation analysis and to select the simulation model whose calculation results were more in line with the actual ones, a test bench was established. An accelerometer and a data acquisition and analysis system were used to measure acceleration of the needles to take seedlings. In the test, the rolling bearing was regarded as ideal revolute joint, and the fit between sliding bearing and shaft with different radii was regarded as the revolute joint with clearance. The average acceleration of the test was larger than that of the simulation under the same condition due to some factors such as manufacturing tolerances, clearance of the rolling bearing and vibration. The conclusion that the revolute joint clearance between the crank and the connecting rod has the greatest influence on acceleration can be also obtained according to the test. By comparing the test and simulation results, the Lankarani-Nikravesh contact force model is more suitable for the analysis of the mechanism with revolute joint clearance than the continuous contact model. The relative errors of average acceleration between simulation based on the Lankarani- Nikravesh contact force model and test were within 3.6% under revolute joint C or D with clearance. The relative errors of average acceleration were within 8.1% under revolute joint B with clearance. The same conclusions can be obtained with the average accelerations of simulation and the average accelerations of test. So the correctness of simulation analysis based on the Lankarani- Nikravesh contact force model was verified by the test results. This research provides the reference for structural optimization design and accuracy allocation of crank-rocker type transplanting mechanism. [ABSTRACT FROM AUTHOR]

Aiming at warp tension control of a let-off and take-up system of a loom, dynamical plant models and effective control techniques for warp tension control were investigated. The influence of periodic shedding motions was analyzed and a sinusoidal signal was utilized to simulate the external disturbance of the system. An adaptive sliding mode controller was designed for warp tension control, of which the sliding mode control method was utilized to handle parametric uncertainties and the adaptation method was utilized to estimate the external disturbance. A PID controller and a conventional sliding mode controller were proposed for comparison. The results indicate that the proposed adaptive sliding mode controller possesses strong robustness and excellent control performance due to its capability of handling the parametric uncertainties existing in the plant model and compensating for the external disturbance of the system effectively. [ABSTRACT FROM AUTHOR]

An Accurate and rapid detection of tea buds can be a critical precondition in an intelligent tea-picking system. Nevertheless, it is still lacking in the robustness, universality, and accuracy during the segmentation of tea buds images under natural light. Fortunately, deep learning can greatly contribute to the artificial extraction of features for higher accuracy of tea bud detection in recent years. However, the current detection of tea bud can also be affected by the light to a great extent. Thus, it is very necessary to establish a new model of tea bud detection with high robustness and low sensitivity for intelligent tea picking in a natural environment. A novel automatic detection model of tea buds was proposed using a regional brightness adaptive correction and deep learning, in order to improve the robustness under different light intensities. First, the Longjing 43 tea was taken as a research object to collect the images under various light intensities. A labelling software was then used to label for the “V” and “I” posture of one bud and one leaf. After that, a data enhancement was performed by adding the Gaussian noise and horizontal mirroring. Second, the RGB images were converted to the grayscale images, of which the gray values were averaged. Subsequently, the distribution of the Average Gray (AG) values and convolution feature diagram were utilized to classify the grayscale images under different illumination intensities. Specifically, three levels were obtained, including the low, medium, and high brightness, corresponding to the intervals [30, 90), [90, 170), and [170, 230], respectively. A gamma brightness adaptive correction was then performed on the images with high brightness using different sizes of partitioning. At last, the multiple models of tea buds detection using deep learning were trained on the same training and test set. The results showed that the YOLOv5+CSPDarknet53 presented an optimal performance of tea bud detection, with the detection precision of 88.2% and recall rate of 82.1%, compared with SSD+VGG16, Faster RCNN+VGG16, YOLOv3+Darknet53, and YOLOv4+CSPDarknet53 models. The precision of detection was improved by 4.8 percentage points after a detection suppression on the YOLOv5 model. Thus, there was much less phenomenon that the same target was boxed for several times. Moreover, the image features of tea buds were of high significance in the brightness intervals [30, 90) and [90, 170), indicating that there was a much fewer influence of the brightness adaptive correction on the detection of the images with the medium or low brightness. There was also a relatively lower contrast between the tea buds and old leaves in the high brightness images. Furthermore, the significance of tea buds was weakened with the deepening of network layers, indicating that the effective features of tea buds cannot be extracted so far. As such, the recall rate of bud detection was only 71.1% for the high brightness images, indicating a relatively high missing detection rate. More importantly, the recall rate of bud detection was promoted by 19.2 percentage points than before, particularly after 2×3 block and regional gamma adaptive brightness correction for the high brightness images. The testing of tea images under various light intensities demonstrated that the YOLOv5 detection model using a regional brightness adaptive correction achieved the detection precision of 92.4% and the recall rate of 90.4%, indicating high robustness and low sensitivity to light changes. Therefore, the finding can provide a promising theoretical basis for the intelligent tea-picking system under natural light conditions. [ABSTRACT FROM AUTHOR]

Leafy vegetable cultivation with culture solution has become a promising new type of planting technology for the vegetable production in a green house. In processing, the seedlings of plugs need to be taken out from the float trays, and transplanted into the cultivation trough. However, a hand transplanting of seedlings is a major traditional operation with high labor intensity and low efficiency. In this study, a novel high-speed mechanism was designed with multiple end effectors for the sparse transplanting of hydroponics seedlings in greenhouses. Specifically, the operations of picking can realize for the whole row seedlings in the float trays, while plant the seedlings in parallel with variable intervals in the cultivation troughs, particularly with high level automation, and great quality. The test platform of sparse transplanting mechanism was composed of three parts: the sparse transplanting component with multiple end effectors, transportation component of seedling tray, and cultivation trough. The sparse transplanting component with multiple end effectors was utilized to transplant the seedlings to empty cultivation trough, connecting the transportation component of seedling tray and cultivation trough. Concurrently, the transportation component of seedling tray was used to convey the seedlings. The transportation component of cultivation trough was used to convey the empty cultivation trough. A systematic optimization was made for the transplanting mechanism, thereby to obtain the best transplanting effect under the combination optimal parameters. In the transplanting mechanism, a rigid cloth belt was adopted to connect the series of needle-type multiple end effectors for equal separation. An elastic belt was also added to alleviate the unequal velocity that resulted from the variable interval process. The collision simulation of multiple end effectors mechanism was conducted on the ADMS software, indicating a large impact force occurred at the end of cylinder. In order to cushion the movement impact, the hydraulic shock absorbers were installed at the end positions of multiple end effectors in the vertical and horizontal directions. The penetration angle and picking seedling depth were determined for the plug seedlings of leafy vegetable, according to the impact factors of transplanting mechanism. Five impact factors of transplanting effect included the belt elastic coefficient(K), average horizontal velocity(v1), absorption energy of oil buffer at the horizontal end(N1), average velocity in the vertical direction(v2), and absorption energy of oil buffer at the vertical end(N2). An orthogonal test was conducted on the factors in each group. It was found that the transplanting efficiency and transplanting success rate were inversely proportional, K, as well as v1, N1 had a great impact on the transplanting success rate of seedlings. A combination of optimal mechanism parameter was obtained through ANOVA: K=0.128 N/m, v1=0.49m/s, v2=0.5m/s, N1=12 J, and N2=20 J. In this case, the better performance can be achieved for the sparse transplanting operating component with multiple end effectors. The transplantation efficiency was 3 816 plants/h, and the transplantation success rate reached 96.7%. This mechanism can meet the actual production requirements of high-efficiency sparse transplanting. [ABSTRACT FROM AUTHOR]

Vegetable pot seedling transplantation has many advantages, such as high survival rate, promoting crop early maturity and improving land use rate. Mechanized transplanting of vegetable can be divided into semi-automatic transplanting and fully-automatic transplanting. Semi-automatic transplanting is mainly carried out by feeding the seedlings into the seedling transplanter manually, which has low efficiency and high labor intensity, and it is not conducive to field operations. At present, the automatic transplanting machine mainly adopts multiple mechanisms to complete a series of actions such as picking up seedling, conveying and planting, but it has the disadvantages of complex structure, high cost and low efficiency. In order to simplify the structure, the way to complete the transplanting operation with a single mechanism is proposed. However, due to the complicated working trajectory of transplanting vegetable seedling and much posture requirements, the transmission ratio of the mechanism is required to be changed greatly, which resulting in the irregular shape of the non-circular gear section of the single planetary gear is not conducive to processing and affects the transmission performance of the gear. A double-planetary non-circular gears linkage of vegetable pot seedling transplanting mechanism is proposed to solve the problem mentioned above in this paper. The transmission part of transplanting mechanism is composed of planetary gear train mechanism and crank rocker mechanism, The main planetary frame rotates at a uniform speed, through the transmission of internal gears and connecting rods, the unequal transmission of non-circular gear system and the periodic variable-speed swing of crank-rocker mechanism are superimposed, which makes the sub-planetary frame swing with respect to the main planetary frame and the transplanting arm rotate with respect to the sub-planetary frame, thus the transmission ratio needed to realize the complex transplanting trajectory and posture is obtained. Non-uniform B-spline curve is applied to fit the pitch curve of non-circular gear to obtain closed, smooth and continuous pitch curves, and the mathematical model of gear train is established based on coordinate transformation theory. Based on the development platform of Matlab, an optimization program is compiled to analyze the effect of transmission case noncircular gear pitch curve and crank rocker mechanism on the shape of trajectory. Further, the effects of the structure and position parameters of the gears and transplanting arm on the target parameters of the transplanting trajectory are analyzed. According to the requirements of 220 mm planting spacing, 120 mm seedling height and 40 mm deep pot for celery transplantation, a set of sharp beak trajectory that satisfies the requirements of the operation posture of picking up seedling and planting is optimized. The optimizing values are that the length of the picking up seedling trajectory is 33 mm, the distance from the lowest point of the trajectory to the lowest point of the planet carrier is 55 mm, the angle of picking up seedlings is 23°, the angle of change in the process of picking up seedlings is 16°, the angle of planting seedlings is 65°, the whole height of the trajectory is 355 mm, and the height of the buckle of the moving trajectory is 125 mm. A three-dimensional model of the mechanism is built and a virtual simulation is performed based on the optimization result. The results show that the simulated trajectory and velocity of the transplanting mechanism are basically consistent with the theoretical results. The trajectory and postures of the transplanting arm are analyzed by a test bench, industrial camera and image processing software. The results show that the trajectory of seedling-taking and seedling-pushing sections coincides with the simulation trajectory basically and the theoretical data, and the error is within 2 mm, which can meet the requirements of transplanting operation, the transplanting mechanism designed is reasonable and feasible. [ABSTRACT FROM AUTHOR]

The seeds cannot fully sprout owing to the seed quality, sowing precision and environmental differences. In order to get the accurate information of the null plug holes and the boundary of plug holes and provide the basis for automatic seedling supplement device, a automatic seedling supplementing test-bed was developed with seedling shortage detecting system and seedling supplementing system as core components. The seedling shortage detection system was composed of a hardware system for image processing, which include a CMOS industrial camera, a controller and a computer, and a software system programmed in MATLAB. Color images (RGB images) of Arabidopsis plug seedlings with the age of 25d and 35d was acquired with the automatic seedling supplementing test-bed. The grayscale images of seedlings and plug holes are obtained by graying the color images applying different linear transformations to three color components of R, G and B. Applying Otsu algorithm, binary images of the grayscale images of seedlings were obtained by threshold segmentation. Then the morphological corrosion operation and expansion operation of the binary images were carried out by the disk 2 × 2 type structure operator. By marking single connected domain, analyzing the characteristics of connected domain and removing the isolated area, the noise in the binary images were removed and the characteristic images of the seedlings were extracted from the background effectively. The feature images of plug tray were acquired by removing feature images of plug seedlings from that of the plug tray according to the extracted seedling information and de-noising. And then statistics on the peak value, peak width and standardizing structure of plug tray were made according to the row and column pixel of binary images of plug trays, so that the edges of plug holes were determined accurately. The statistics of the pixel of the seedling image in each plug hole were made to determine whether the hole was short of seedlings according to the feature images of the seedlings, the position, and the edge information of the plug holes. The results showed that the statistics value of the seedlings image pixel of the plug holes with the Arabidopsis plug seedlings of 25 and 35d were 1 895 to 4 572, and 3 725 to 8 710, respectively, while the statistics value of the seedlings image pixel of the plug holes without seedlings was 0. There were significant differences in the statistics value of the seedling image pixels between the plug holes with seedlings and the null plug holes. The testing results of the missing plug tray hole were the same as the actual situation, and the statistical value of seedling pixels corresponds to the projection area of stem and leaf. According to the threshold value of seedlings at different growth stages, the undeveloped seedlings can be marked for removing, so the seedling early stage was the super time for the detection of the null plug hole and the determination of the undeveloped seedlings. The accuracy rate of judging the null plug holes and the seedling holes with the Arabidopsis plug seedlings of 25 and 35d were all 100% applying the detection device. The accurate determination of position of the null plug hole provides basis for automatic supplementing system taking out the substrate without seedlings, removing dysplasia seedlings and supplementing the healthy seedlings with same age. [ABSTRACT FROM AUTHOR]

The seeds cannot fully sprout owing to the seed quality and environmental differences. So it is difficult to provide seedling pots without empty seedling holes for automatic transplanting. In order to reduce the number of seedling shortage and the manual labor intensity of seedling supplement, and to improve transplanting quality, a method for supplementing seedlings in cotyledon phase was presented in the paper. According to the delicate seedling, undeveloped root system and the unconsolidated substrate in pot, a new type of end-effector for supplementing pot-seedling in cotyledon phase with 4 seedling shovels was designed. The 4 angular seedling shovels were synchronously driven up and down by stepper motor moving the X-shaped press rod. They can shape enveloping surface when they are inserted into the lower limit position of the whole pot and surrounded the seedlings from the 4 sides of seedling substrates during seedling. And then the pot seedling was taken out from seedling hole and transplanted to the target hole. The seedling supplementing was finished while the pot seedling was left in the target pot hole and the seedling spades lifted it up along the inclined guide. The 3 factor and 3 level orthogonal tests were conducted respectively with the Zheza809 tomato pot seedlings in cotyledon phase with the seedling age of 16, 21 and 26 d cultivated in standard seedling tray with 72 holes. In the test, the velocities of inserting and taking out of matrix for the shovels were measured by speedtro-50 laser velometer, and the average velocities were 29.85 and 31.12 m/s respectively. The mixture ratio of peat, vermiculite and perlite in nursery matrix, the moisture content of the substrate and the seedling age were chosen as factors. The matrix net rate, which is the percentage of the weight of pot seedling taken out from the pot holes by the end-effector in the total mass of the pot seedling in the pot hole, was set as index. The results indicate that the net rate of taking out the free substrate without seedlings or the pot seedlings in cotyledon phase is affected significantly by the pot seedling age and the mixture ratio of peat, vermiculite and perlite in nursery matrix. The net rate increases with the seedling age, which reaches the highest value at the end of cotyledon phase and the mixture ratio of peat, vermiculite and perlite in nursery matrix of 2:2:1. The effect of matrix water content from 67.1% to 79.2% on the net rate is not significant, while the net rate keeps a high value owing to good cohesive force and plasticity of the substrate when the moisture content of the substrate is 74.1%. When the growth age is 26 d, the mixture ratio of peat, vermiculite and perlite in nursery matrix is 2:2:1 and the moisture content of the substrate is 74.1%, the average net rate reaches the maximum of 89.5% and the shape and volume of the seedling pot keep complete. To further verify the optimal combination obtained by the test, the experiments of seedling taking out and supplementing were carried out with tomato pot seedlings with the age of 26 d, the mixture ratio of peat, vermiculite and perlite in nursery matrix of 2:2:1 and suitable substrate moisture content. The results show that the success rates for the free substrate without seedlings and pot seedlings are both 100%, which can take out the pot seedlings in cotyledon phase with crisp plant and loose matrix as a whole and fill them into target hole on the seedling pot completely. [ABSTRACT FROM AUTHOR]

To improve the efficiency of mechanization in transplanting vegetable seedlings and achieve the automation of vegetable transplanter in dry land, an automatic vegetable pot seedling transplanter for dry land was developed. This transplanter is mainly composed of 2 rotating seedling picking-up mechanisms of planetary gear train with ellipse gears and incomplete non-circular gears, a horizontal and longitudinal intermittent seedling sending device, 2 eccentric disc dibble-type planting apparatuses, and a power transmission system. Two rotating seedling picking-up devices and 2 eccentric disc dibble-type planting apparatuses were symmetrically arranged along the longitudinal surface center of the machine, constituting 2 sets of automatic seedling picking-up and planting systems. The seedlings were provided automatically from 2 standard seedling pots with 128 holes using the horizontal and longitudinal intermittent seedling sending device. The engine drive shaft could transfer power to the principal axis of the apparatus through chain drive to enable the rotating and planting of the apparatus. Meanwhile, the principal axis of the apparatus could transfer the power to the rotating seedling picking-up mechanisms of planetary gear train with ellipse gears and incomplete non-circular gear and intermittent seedling sending device. Subsequently the intermittent seedling sending device could move horizontally and longitudinally to send the seedling pots to the target place, where the seedling picking-up mechanism took the seedlings from the pot to the eccentric disc dibble-type planting apparatus. To test the performance of this automatic vegetable pot seedling transplanter for dry land, the experiments were conducted in the test field where the soil condition met the mechanical industry standard in People's Republic of China Dry Land Planting Machinery (JB/T 10291-2013). The tomato seedlings (ZheZa 809) used in this experiment were cultivated in the standard seedling pots with 128 holes and transplanted at the age of 35 days with an average height of 150 mm. The seedling sending, picking-up, delivering and planting were all carried out at a constant transplanting frequency by adjusting the speed of the input belt pulley of the walking gear-box. The seedling transplanting efficiency was tested at the low speeds of 45, 60, 75 and 84 plants/min, respectively, as well as at the high speed of 96 plants /min. The coefficient of variation for planting spacing, missing transplanting rate, qualified rate of planting depth and qualified rate of transplanting were determined according to the mechanical industry standard Dry Land Planting Machinery (JB/T10291-2013). The seedling-standing ratio was calculated based on the Technical Specifications of Quality Evaluation for Rape Transplanter (NY/T 1924-2010) according to the standards for agriculture industry in People's Republic of China. The results showed that the coefficient of variation for planting spacing and the missing transplanting rate increased slightly at the range of 6.6%-8.9% and 1.7%-2.8% accordingly when increasing the planting frequency from 45 to 96 plants/min. However, the qualified rate of planting depth, the qualified rate of planting perpendicularity and the qualified rate of transplanting decreased slightly in the range of 97.5%-98.9%, 96.7%-97.8%, and 91.1%-94.7% with the increasing of planting frequency. The coefficient of variation for planting spacing, the missing transplanting rate, the qualified rate of planting depth and the qualified rate of planting all met the requirements of the machinery industry standards (JB/T 10291-2013), and the qualified rate of planting perpendicularity was also within the specified value in the standards for agriculture industry (NY/T 1924-2010). The automatic seedling-sending device, the seedling picking-up device and the planting apparatus of the automatic transplanter coordinated well with each other to complete the process for sending seedlings, picking up seedlings, delivering seedling, planting and soil covering automatically. [ABSTRACT FROM AUTHOR]

At present, the main way of fruit harvesting is still dominated by manual picking. Although the workload of the laborer can be reduced by the use of mechanical equipment in the process of fruit harvesting, the unstable harvesting rate and the high proportion of fruit damage are hindering the development of harvesting equipment, especial in fruit harvesting machines, which are the key factors to improve harvesting machine. In order to improve the performance of harvesting equipment in the market of agricultural machinery, it is necessary to make accurate evaluation of the fruit motion in process of picking with fruit harvesting equipment, and then determine the main stages and key factors leading to fruit damage. In this paper, a flattened electronic fruit based on Orange Impact Recording Sensor (OIRS) was designed to detect the mechanical impact caused by the three-dimensional vibration harvesting system and analyze the fruit motion. The dynamics model of sugar orange was built and analyzed, which was equivalent to solve nonhomogeneous linear ordinary differential equation with constant coefficients. The dynamics model was solved and the theoretical condition of fruit abscission from tree body was obtained. The fruit falling process was recorded by high-speed photography in the detachment test of electronic fruit, and the amplitude and binding force of fruit were measured. All the parameters in the theoretical model were calculated, and the result of 17.25>11.6 N was obtained, which demonstrated that the normal inertia force of fruit was greater than that of binding force when the fruit was detached from the tree. So the theoretical model of fruit abscission was verified. Three-axis accelerometer was embedded in the OIRS, and was used to detect and record the acceleration in the process of harvesting. And the final resultant acceleration values from three directions were obtained with the method of FFT (Fast Fourier Transformation) by MATLAB. Four vibration harvesting experiments were carried out in orchard filed and recorded the maximum mechanical impact in vibration and falling stage, the maximum mechanical impact recorded by the electronic fruit was 217 g in the vibration stage, and the average impact reached 123 g. The maximum mechanical impact was 155 g in the falling stage, and the average impact was only 76 g. The results showed that the possibility of fruit damage in the vibration stage was higher, and the potential damage risk can be reduced by adjusting and improving working parameters of the harvesting machine. The higher impact caused by the fruit contact with the ground during the falling stage can also lead to fruit damage, in order to reduce the fruit damage during the falling stage, the damping and buffer materials can be used on the surface of fruit collect equipment. The use of electronic fruit can detect the mechanical shock effectively caused by the vibratory fruit harvesting mechanism with three-dimensional excitation in the fruit picking process, and it can be also used to evaluate damage in the process of harvesting fruit of the machine system. Though there are some differences in fruit size, weight and the way to fixed in fruit tree branch when comparing the actual picking environment and state, experiment results of mechanical harvest using electronic fruit technique in orchard filed demonstrate that this electronic fruit device has practical value and provides a reference for the improvement of the other fruits harvesting machine. [ABSTRACT FROM AUTHOR]

For rice seedling transplanting, there are more than 5 kinds of planting patterns in China, including equal row carpet seedling transplanting, wide-narrow row carpet transplanting, equal row pot seedling transplanting, wide-narrow row pot seedling transplanting, and semi-pot seedling transplanting. The zigzag wide-narrow row rice seedlings transplanting is a new method of planting adjacent rows of rice seedling alternately, and distributing wide and narrow rows. This kind of planting method absorbs the merits of traditional equal row pot seedling planting, wide-narrow row carpet seedling planting and zigzag planting. The pattern of zigzag and wide-narrow row pot seedling transplanting can increase the light penetration and ventilation of the paddy-field, which brings some advantages such as reducing the plant diseases and insect pests, increasing lodging resistance ability of rice and improving the rice yield and quality for rice production. In this paper, a variable and differential transplanting mechanism for zigzag wide-narrow row rice pot seedlings was presented. This mechanism consists of 2 major parts that are transmission case and gear case. There are 10 gears, including 2 pairs of noncircular gears, 2 pairs of bevel gears as well as one pair of spur gears, employed to transform one input constant rotational speed into 2 output rotational speeds which are used to drive the noncircular gear case. Based on the non-uniform and spatial transmission of differential gear train, this mechanism can achieve a special figure-eight spatial-shaped trajectory, which can meet the kinematic requirements of zigzag wide-narrow row pot seedling transplanting. In order to obtain closed, smooth and continuous pitch curves, non-uniform B-spline curve was applied to fit the pitch curve of non-circular gear, and the mathematical model of gear train in gear case was established based on coordinate transformation theory. Moreover, the trajectory and attitude requirements of the zigzag wide-narrow row pot seedling transplanting were parameterized into 9 specific kinematics optimization objectives. Based on the development platform of MATLAB GUI, an optimization program was compiled to analyze the effect of transmission case noncircular gear pitch curve and gear case noncircular gear pitch curve on the shape of trajectory. Further, the effects of the structure and position parameters of the gears and transplanting arm on the target parameters of the transplanting trajectory were analyzed. By human-machine interaction, a group of structural parameters including data points of pitch curves meeting the requirements were optimized. Using these parameters, a 3D (three-dimensional) model of the mechanism was built, and virtual simulation was carried out. The simulation trajectory and velocity data of the transplanting arm clip were basically consistent with theoretical results. The parts of the right transplanting mechanism were processed and assembled. The trajectory and attitude of transplanting arm were analyzed by test bench, industrial camera and image processing software. The results were consistent with the theoretical data, which verified the feasibility of the transplanting mechanism and the rationality of the structure. [ABSTRACT FROM AUTHOR]

With the growth of orchard area and fruit yield in recent years, it is still a big problem for farmers to harvest fruit efficiently in China. Because the shaking-type harvester can make mature fruit detached quickly and effectively, the existing fruit harvesters are mostly shaking type. But the efficiency of shaking-type harvester is not high enough. To improve the harvesting efficiency, the three-dimensional shaking method was proposed and the vibratory harvesting mechanism with three-dimensional excitation was designed. Firstly, a Chinese hickory tree model was established for transient dynamics analysis by finite element software (ANSYS). One-dimensional and two-dimensional shaking method was discussed respectively, and then the influence of the loading direction on the acceleration response of tree was analyzed. Simulation results show that the loading direction of these 2 shaking methods has remarkable effect on the acceleration response, but it is difficult to make fruit tree branches produce enough big acceleration response in all directions. So, the three-dimensional shaking method was proposed on the basis of one-dimensional and two-dimensional shaking method, which has effect not only on the cross section direction of fruit tree’s branch, but also on the axial direction. After analyzing the acceleration response of different kinds of shaking methods and the three-dimensional displacement patterns with different speed ratios, the conclusions are as follows: 1) Fruit tree shaken by three-dimensional load has a more uniform acceleration than by one-dimensional and two-dimensional load; 2) it has the most uniform acceleration distribution when the speed ratio of crank in the spatial linkage shaking mechanism is 1:1. Secondly, according to the generation method of three-dimensional displacement load and the dynamics simulation result of fruit trees, the vibratory fruit harvesting mechanism with three-dimensional excitation was designed, which mainly consists of the case, the spatial linkage shaking mechanism, the driving mechanism and the clamping mechanism. The transmission ratio of the driving mechanism can be changed to obtain different three-dimensional displacement loads. And the kinematics analysis of the spatial linkage shaking mechanism was performed. Thirdly, after kinematics analysis of the spatial linkage shaking mechanism, the stroke and acceleration that were affected by the change of related parameters were calculated with MATLAB software. In order to achieve the optimization objective of the maximum acceleration, genetic algorithm was used to optimize parameters of this mechanism. The ranges of parameters were determined by constraints of the spatial linkage shaking mechanism. Then the optimization software was based on MATLAB platform and the optimization result indicates that the maximum output acceleration of the mechanism is 117.3 m/s2. A prototype of vibratory fruit harvesting mechanism with three-dimensional excitation was manufactured and assembled according to the result of parameter optimization. Then the dynamics response experiment of fruit tree was carried out. In order to evaluate the performance of the vibratory fruit harvesting mechanism with three-dimensional excitation, an eccentric block type vibration motor was used for comparison in the experiment, and the accelerations of test points on the fruit tree were measured by data acquisition and analysis instrument. Statistics results indicate that the test points on the tree have obvious acceleration response in 3 directions to the vibratory harvester with three-dimensional excitation, while obvious acceleration was only generated at the cross section of the branch by the eccentric block type vibration motor and the acceleration was small along the axis direction of the branch. Finally, the coefficient of variation was calculated according to the average acceleration result of the test points by 2 shaking methods. Results show that it has a smaller coefficient of variation when the tree is excited by the vibratory harvester with three-dimensional excitation, which means the vibratory harvester with three-dimensional excitation can make the branches vibrate in a uniform level. So the harvesting efficiency is expected to be improved with the excitation of few times. [ABSTRACT FROM AUTHOR]

Most orchard gardens are distributed in the subtropical and tropic zone, and especially in mountainous and hilly region in China. With the development of science and technology and the increasing cost in labor, the mechanized operation for fruit collection is needed. Existing small fruit collecting devices have bulky and complex structure and need to be equipped with high-power drive, and strict requirement in the tree spacing. In order to adapt to the mechanization collection of small fruit and improve the mechanical collecting device, based on the existing fruit collection equipment at home and abroad, and considering deployable and foldable mechanisms of the equipment, a collecting device with flank deployable and foldable mechanism was introduced in this paper. This collection device mechanism can reduce the bulk in process of moving, adapt in line spacing of the fruit trees, have larger coverage area in unfolding state, and can adjust quickly and effectively in operation to improve collecting efficiency. The collecting device consisted of three parts: flank deployable and foldable mechanism (the core mechanism), lifting mechanism, and mobile clamping mechanism. The displacement and coordinate point G at the end of the flank deployable and foldable mechanism were calculated by transformation matrix. Then kinematics of the flank deployable and foldable mechanism was analyzed, and the main components of the mechanism were optimized using genetic algorithm (GA) operated in MATLAB. Rod AB, AD, PE were taken as the main optimization variables by comparing the influence of variable rod length on the displacement of point G and ∠EFG. Given the radius in folding and unfolding, the maximum displacement of point G during the unfolding process and the minimum dimension sum of the rods were taken as the optimization objectives. In order to obtain the more preferable rod dimension, the optimization range of the rods was expanded about ±50 mm. And the final optimization range and optimal solution of the main rods dimension were obtained based on the restrictions by iterative calculation at last. The optimal dimensions of the main components were lAB=277.88 mm，lAD=661.64 mm, lPE=306.58 mm. The obtained results were used to modify the 3D model of the flank deployable and foldable mechanism, and the 3D model of this mechanism was imported into the dynamic analysis software ADAMS. From such model, then the motion trajectory of the mechanism was simulated and the dynamic simulation results showed that the driving torque was 2.4 N·m. The motor type was determined based on the results achieved by simulation. Finally, a prototype of the flank deployable and foldable mechanism was manufactured and tested based on the optimal theoretical model, and the trajectory of point G was recorded by the Phantom v5.1 high-speed camera. Due to precision and errors of the prototype caused by machining and assembling and errors from camera shooting angle and image processing, there was a slight deviation between trajectory of experiment and virtual simulation, but they were basically consistent, which verified accuracy and reliability on the theoretical design of this collecting device. Experiment results of mechanical harvest using a small fruit collecting device with flank deployable and foldable mechanism demonstrated that this collection device had practical value and this research provides a reference for the improvement of the other collection mechanism. [ABSTRACT FROM AUTHOR]