Development Of Automatic Strawberry Plug Seedlings Transplanting System For Elevated Groove Cultivation

Labor-saving elevated groove cultivation was developed in Japan from the 1980’s, which was then popularized to China and other countries. Strawberry tray seedlings are much bigger than common seedlings and have particular requirements for arch orientation. Now different transplanters for field and plant factory have been developed, but no transplanter can be applied to elevated groove cultivation. Development of automatic strawberry plug seedling transplanting system for elevated groove cultivation is necessary. The main research conclusions and contents were as follows:(1) Morphological parameters of elevated facilities and strawberry plug seedlings were measured to get their parameter data and error ranges, then a transplanting system was developed, which was proposed to pick four seedlings in plug and plant them into four rows of grooves simultaneously after digging.(2) The end-effector was designed based on transplanting requirements and mechanical characteristics of strawberry seedlings. The end-effector was composed of one arch reversing mechanism and two grippers. Take reducing of gripper width and swing range of connecting rod as dual objectives, optimal mechanism parameters of the gripper were obtained by performing linear programming. To detect the stuck phenomenon between the finger circular shaft and linear bearing, kinematics and dynamics simulation were performed by ADAMS, and then optimization was put forward to improve the gripper’s transmission efficiency.(3) Digging experiments were carried out to verify the carrying capacity of elevated groove and molding characteristics of the substrate. Test results showed that the elevated groove have the ability to withstand static and dynamic loads caused by punch and the substrate with higher moisture conditions was capable of forming a good hole. Mechanical structure of the digging device was then designed.(4)Transplanting experiments were done.With orthogonal test design. The picking experiments of single griper were tested, and which howed that the important factor rank were fingers picking angle、extraction acceleration、finger width, the validation experiment showed that average picking success rate was 90.62%.The planting experiments were carried out, the upright degrees and height differences were correspondingly decreasing and increasing when the deviations were increasing. The composite transplanting experiments were done when the end effector combined grippers and arch reversing mechanism. End-effector can accomplish the picking, arch reversing, planting work, respectively.In this paper,a novel constrained extraction test to detect the permitted force and to help judge whether the gripper satisfied the picking requirement. And the automatic transplant system which can realize compositive digging-planting and synchronous arch-distance reversing provides a reference and foundation for other kinds of plug seedlings in elevated groove cultivation.