Design and Optimization of a Boat-Bottom-Shaped Transplanting Device for Sweet Potato (Ipomoea batatas) with Low Seedling Damage Rate

A transplanting manipulator and a transplanting conveyance device were devised to address the problems with current sweet potato transplanters, which cannot properly finish boat-bottom-shaped transplanting and have a high seedling damage rate. The ground wheel transmits power to the two devices in a specific transmission ratio to ensure their synchronous movement and avoid accumulated deviations. We selected the transplanting manipulator’s parameter combination that satisfies the optimal transplanting trajectory by the VB program. To avoid damage to the seedlings during clamping, the clamping force is only provided by the spring through the structural design. Combined with the agronomic requirements of boat-bottom-shaped transplanting and the characteristics of soil resistance during the transplanting process, the transplanting depth and crank rotation speed were selected as test factors. The qualified rates of node depth in the seedling middle (QRNDSM), the qualified rates of seedling root depth (QRSRD), and the qualified rates of stalk length into the soil (QRSLS) were established, and Design-Expert was used for the quadratic regression and orthogonal combination tests to optimize the factors. The results of the verification tests reveal that when the transplanting depth is in the range of 45.56 to 58.26 mm and the crank rotation speed is in the range of 39.39 to 43.45 rpm, the maximum QRNDSM is 94.91%, the maximum QRSRD is 95.42%, and the maximum QRSLS is 94.93%, which satisfies the industry standards. Research into sweet potato transplanting can benefit from this work, especially in the direction of sweet potato boat-bottom-shaped transplanting.