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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]

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]