Satoshi Yamamoto

Development of a Movable Bench System for Strawberries and the Potential for Plant Growth Measurement

Abstract A circulating-type movable bench system was installed in a research greenhouse in Miyagi Prefecture. The system is 13.5 m long and 7.7 m wide, and chiefly comprises two longitudinal conveying units, two lateral conveying units, two nutrient supply units, a chemical sprayer, 52 planting benches, and a control unit. The cycle times for each speed mode of lateral convey mode were 44.5 s at low speed, 28.8 s at medium speed, and 23.8 s at high speed. The waiting time can be shortened in high speed mode. A prototype of a plant growth measurement system was then developed in a laboratory to estimate plant height and width using a motion control sensor to capture an RGB image and depth image when the bench passed it. Our results suggest fixed-position observation using the movable bench system to be feasible, although further work will be needed to clarify the accuracy of measurement and the relationship between analysed image data and plant condition.

Automation technologies for strawberry harvesting and packing operations in Japan1

This paper describes a strawberry-harvesting robot, a packing robot, and a movable bench system. The harvesting and packing operations in strawberry production require harder, more time-consuming work compared to other operations such as transplanting and chemical spraying, making automation of these tasks desirable. Since harvesting and packing operation account for half of total working hours, automation of these tasks are strongly desired. First of all, based on the findings of many studies on strawberry-harvesting robots for soil culture and elevated substrate culture, our institute of the Bio-oriented Technology Research Advancement Institution and Shibuya Seiki developed a commercial model of a strawberry-harvesting robot, which is chiefly composed a cylindrical manipulator, machine vision, an end-effector, and traveling platform. The results showed an average 54.9% harvesting success rate, 8.6 s cycle time of picking operation, and 102.5 m/h work efficiency in hanging-type growing beds in an experimental greenhouse. Secondly, a prototype automatic packing robot consisting of a supply unit and a packing unit was developed. The supply unit picks up strawberries from a harvesting container, and the packing unit sucks each fruit from calyx side and locates its orientation into a tray. Performance testing showed that automatic packing had a task success rate of 97.3%, with a process time per fruit of 7.3 s. Thirdly, a movable bench system was developed, which makes planting beds rotate in longitudinal and lateral ways. This system brought high density production and labour saving operation at a fixed position, such as crop maintenance and harvesting. By setting up the main body of a strawberry-harvesting robot on working space, unmanned operation technique was developed and tested in an experimental greenhouse. Field experiments of these new automation technologies were conducted and gave a potential of practical use.