Parametric analysis and inversion of transplanting mechanism with planetary non-circular gears for potted-seedling transplanter

Abstract: The transplanting mechanism is the ultimate mechanism that plants seedlings into fields, and whose performance directly affects the verticality rate and injury rate of seedlings, thus affecting the survival rate of seedlings and final productivity. At present, in order to achieve "zero speed" transplanting to improve upright degree after transplanting, research into transplanting mechanisms focus on the trajectory of the transplanting tip and planting speed. However, due to the diversity of seedling organisms and the kinematic accuracy of transplanting mechanism, it is still difficult to achieve "zero speed" transplanting; thus, the upright degree of seedlings cannot be guaranteed. To meet the agricultural demands of seedling transplanting in dry land, the transplanting mechanism with planetary non-circular gears was proposed. Several discrete points on the motion trace of the transplanting tip were selected as data points, and then the cubic non-uniform B-spline curve was applied to control and express the whole trace curve. On this basis, the parameter inverse model aimed to the curve of this mechanism was established, and the equations of (angular) displacement, (angular) velocity, and (angular) acceleration for the transplanting tip were deduced. The parameter inverse and design software for this mechanism, based on the development platform of MATLAB GUI, was compiled to analyze the effect of several main date points on the trajectory and posture of the transplanting tip and the hole shape. On the basis of the analysis of the effect of the data points, and in order to meet the demands of the trajectory and posture of the transplanting tip and the hole shape, the data points were adjusted to optimize the mechanism parameters by the software. The new mechanism parameters improved the verticality rate of seedlings and reduced the injury rate of seedlings. The data points affected the inclination angle between the transplanting tip and horizontal axis when catching seedlings, the posture of the transplanting tip when planting, and the shape of motion trajectory and hole in the process as the transplanting tip exited from the hole to the height of seedling after transplanting. This method is intuitive and convenient, so it is suitable for the study of the mechanism that has complicated demands for posture of trajectory. Compared with the seven-linkage transplanting mechanism, the multi-linkage transplanting mechanism and the transplanting mechanism with planetary elliptic gears, this transplanting mechanism has higher verticality rate of seedlings and lower injury rate of seedlings. At the same time, its' maximum acceleration and the fluctuation range of acceleration is smaller, so it works smoothly.