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This research was conducted to evaluate the performance of disc, carrousel and dibble-type transplanters for potted tomato and watermelon seedlings in field conditions. Intra row distance, transplantation depth, the gripping force of seedlings to the soil, vertical position, damage of seedling and seedling survival rate were determined to evaluate performance of transplanters. The disc and carrousel-type transplanters place the seedlings into furrow and the dibble-type transplanter places the seedlings into the holes. According to field experiment results, distribution uniformity of intra row distance of dibble and carrousel-type transplanters were very well with the coefficient of variations between 3.52% and 5.55%. The highest transplantation depth was obtained when the carrouseltype transplanter was used. The disc and carrousel-type transplanters placed the seedlings into furrow, increasing the gripping force between seedlings and soil. The angle between the seedlings and vertical plane was under the 30° for all transplanters used. Only the disc-type transplanter damaged seedlings over 3%. The survival rate of seedlings for all transplanters were higher than 90% and this rate is acceptable for transplanting vegetable seedlings. [ABSTRACT FROM AUTHOR]

Rice potted-seedlings transplanting is one kind of rice planting way, and it can increase the production and improve rice quality because it has the advantages of not hurting root and not needing recovering period. The rice pot seedling transplanting will have a good prospect in the future, but at present the application of rice pot seedling transplanting machine is less in China because there are defects for domestic transplanter with tossing transplanting such as uncontrollable seedling perpendicularity, complex structure, low efficiency and heavy vibration. Foreign rice potted-seedling planting technology is not suitable in China for complicated structure and high cost, and the key to improve the mechanization of rice planting is to research the rice potted-seedling transplanting mechanism suitable to China. Aiming to the above problems, a three-transplanting-arm rice potted-seedling transplanting mechanism of planetary gear train with non-circular gears and incomplete non-circular gear, which is applied in automatic rice potted-seedling transplanter, was designed. The mechanism consists of an incomplete non-circular gear, 3 pairs of conjugate non-circular gears and 3 planting arms, which can transplant seedlings 3 times a week. It means that under the same transplanting efficiency, it can reduce the transplanting spindle rotation, so as to reduce the vibration and improve the success rate of transplanting. Firstly, the shortcomings of the rotary transplanting mechanism with 2 transplanters were analyzed, and the design requirements were put forward. According to the requirements, the implementation plan was advanced. Then, the operation principle of rice potted-seedling transplanting mechanism was introduced, the mathematical expression in parametric form for the trajectory and the equations of non-circular gears and incomplete non-circular gears were derived, and the kinematic model of transplanting mechanism was established. A computer-aided analysis and optimization software of this kind of rice potted-seedling transplanting mechanism was developed with the Visual Basic 6.0. With the method of human-computer interaction based on visualization, the optimization design of the transplanting mechanism was carried out. Using this software, by tuning the design parameters, the influence of every parameter on the optimization object could be found out. The curve of non-circular gears was optimized and the structural parameters were obtained, which can satisfy the requirements of trajectory and attitude in the transplanting process for rice potted-seedling. The 3D (three-dimensional) model of transplanting mechanism was built and assembled in UG's entity modeling module. The virtual prototype was imported into Adams software after the interference checking of 3D model assembly was finished. According to the comparison between the virtual prototype simulation and the theoretical analysis of VB (Visual Basic), the trajectory of them was fundamentally consistent, so the correctness of the model of VB was verified, and the simulation results initially showed the design of mechanism was rational. In order to further verify the correctness of the design, the core components of transplanting mechanism were machined and assembled. Then, the physical prototype of the transplanting mechanism was developed to carry out the kinematics test in the test shelf. The results turned out that the static trajectory of the elastic tip of this transplanting arm and transplanting posture were basically consistent between the virtual prototype simulation and the physical prototype test, which proved the rationality and effectiveness of the parameters of transplanting mechanism. And the feasibility of this transplanting mechanism was verified. At the same time, the mechanism proposed solved the problem of seedling lodging and low transplanting success rate, and the efficiency of transplanting was improved. The research can provide a theoretical basis f [ABSTRACT FROM AUTHOR]

The transplanting mechanism is an end manipulator which picks seedlings from a seedling box and pushes them into a rice field. A wide-narrow distance mechanism is a kernel part of the rice transplanter to place seedlings in a wide row and narrow row alternation. Because of the spatial movement property of a bevel gear pair, and the requirement of variable speed transmission, a noncircular bevel gear was widely used in a wide-narrow transplanting mechanism design. On the condition of a determinate transmission scheme, how to obtain a sound planting trajectory and proper picking posture which is important for the wide-narrow distance transplanting mechanism to achieve upstanding and fewer damaged seedlings in planting work becomes a key issue. In general, putting forward a new mechanism, building a calculate model, and compiling a parameters optimization program are the three main steps for transplanting mechanism design. But there is some uncertainty of parameters-choosing and parameters effecting design goals in the design of the trajectory and planting paw posture in the traditional way. Furthermore, the special noncircular gear such as elliptical (or bevel) gears, eccentric-noncircular (or bevel) gears whose pitch curve are accessible to expression are often used in the transmission scheme design, which limits the formation of trajectory shape and planting paw posture. A new way to design a spatial planetary noncircular gear train by using reverse design methods was put forward based on the spherical curve. An ideal plane curve which is smooth, continuous, and closed was expressed by a free spline curve, and then a spherical curve was obtained by mapping the ideal plane curve onto the spherical surface with a preserved geodesic curvature. A two bar mechanism with three degrees of freedom was used to describe the spherical curve. According to the spatial geometric relationship between the two bars and the center of sphere, the transmission ratio model was established. The transmission ratio of every single gear pair and the pitch curve of every gear were resolved by attaching a noncircular gear and a noncircular bevel gear to the two bar mechanism with three degrees of freedom. The parameter inverse and design program for a wide-narrow distance transplanting mechanism with noncircular gears and noncircular bevel gears, based on the development platform of MATLAB, was compiled and the ideal spherical surface trajectory was obtained by modifying the data point of plane trajectory. In addition, a group of mechanism parameters was reversed by the method of human-computer conversation afterward. Finally, a model machining of the transplanting mechanism was processed and a testing trajectory, similar to the theoretical trajectory was gained, which verified the feasibility of this reverse design method and supplied a new method for the design of a wide-narrow distance transplanting mechanism. [ABSTRACT FROM AUTHOR]