Harvesting robot for strawberry grown on table top culture (Part 2) harvesting robot with a suspended manipulator under cultivation bed

摘要

In part 1 of this series, a harvesting robot consisting of a 5 DOF polar-coordinate manipulator, a harvesting end-effector using sucking force, a visual sensor and a traveling device was manufactured and tested with strawberry grown on table top culture. From the results, it was observed that the table top culture was a suitable cultivation method for robotic operations because there were few obstacles around the target fruits, and that harvesting using a sucking force inflicted no damage on the fruits. However, it took the robot 14 to 20 seconds to harvest a single fruit because of the complicated construction and control method of the manipulator. In this study, a cartesian coordinate manipulator suspended under the planting bed of strawberry was employed in order to simplify construction and control method of the manipulator intended for practical use. The robot was capable of moving along the planting bed without a traveling device because one prismatic joint of the manipulator played the role of a travelling device. Furthermore, depth measurement by a visual sensor was simplified because distance between the robot and the fruits was kept approximately constant by suspending the robot under the planting bed. Harvesting experiments were conducted in a greenhouse by using the manipulator equipped with an improved end-effector and a visual sensor. From the results, time required to harvest a fruit was reduced to around 10 seconds because of the simplified construction and control method of themanipulator.