To reduce the production costs of sweet potato cultivation, new transplanting method of bent-postured cuttings （BC） using a semi-automatic vegetable transplanter （SVT） was developed in sweet potato. Three types of BC, 300 mm in length, were prepared and investigated feeding-out rates using SVT. As the results showed that BCs by crossing the tip of shoot with the cut-side end were successfully feeded out in high frequency, 88%. Because the width of crossing-type BC was the narrowest compared to other BCs, it is considered that crossing-type BC has become easier to fall out of serving cup of SVT. Cuttings immediately after reaping often broke when bent, but the breakage rate of cuttings left in the shade for about 5 hours was less than 1%. Crossing-type BCs was possible to produced 463 in an hour. To reveal the impact of crossing-type BC, cultivation experiments were conducted using sweet potato cultivar ‘Suzuhokkuri’ and ‘Beniharuka’. The transplanting of crossing-type BCs showed higher tuber yield than conventional system, transplanting of straight cuttings, in ‘Suzuhokkuri’, however such advantage was not shown in ‘Beniharuka’.

Previous studies have shown that the end effectors of tomato-harvesting robots equipped with fruit-grasping and pedicel-cutting mechanisms, have limitations because of increased multifunctionality and size, which restricts access to cluster-grown fruits and reduces harvesting performance. To address this issue, we developed a smaller end-effector that acts directly on the pedicel to detach the fruit from the abscission layer without gripping it. In this study, we aimed to enhance the harvesting performance of this new mechanism by introducing two support racks: a fruit cluster support rack to restrict the movement of fruit clusters and a main stem support rack to restrict plant movement. Harvesting examinations were conducted using the new end effector, with the robot approaching support racks each with 50 fruits. The results demonstrated that 45 fruits were harvested without damage using a two-string fruit cluster support rack; 42 fruits were harvested with a three-string main stem support rack; and 29 fruits were harvested without any support racks. Although the time required for vine lowering and cluster arrangement increased in comparison to the no- support rack plot, the total labor time was reduced over the course of the year compared to manual harvesting: 361.6 h/10a with the two-string fruit cluster support rack and 338.7 h/10a with the three-string main stem support rack. Notably, the fruit cluster support rack aligned the clusters towards the aisle, potentially enhancing the fruit and pedicel recognition capabilities, suggesting that this cultivation method is more suitable for robotic harvesting.

Weed control around electric and mesh animal fences surrounding fields is effective for preventing animal damage. Robotic mowers are effective for labor saving in weed control in the near space of animal fences, mesh fence and electric fence. Because robotic mowers attack the posts for mesh fences and touch the electric wires in electric fences when weeding, some troubles in fence management are expected. Practical experiments were conducted in weeding work with robotic mower around mesh and electric fences. Results did not indicate that the robotic mower exacerbated loosening of the mesh fence posts. In some cases, loosening of the posts progressed either with or without robotic mower usage. To prevent fence collapse, checking and refixing the mesh fence posts once a year is considered effective, irrespective of whether robots are used. Practical experiments conducted around electric fences revealed that the robotic mower can control weeds under the electric wire. Furthermore, a simple tensioner consisting of a spring and pulley to prevent loosening of the electric wire was produced and tested. Findings demonstrated that the tensioner can mitigate and prevent loosening of the wire when the mower height is about 100 mm higher than the electric wire height. Because of the robotic mower structure, weeds around the posts are left uncut. To keep the weed height around the posts lower than the lower electric wire （200 mm height）, some measures must be used at least once a month.