Bimanual Grape Manipulation for Human-Inspired Robotic Harvesting

Most existing robotic harvesters utilize a unimanual approach with a single arm grasping and detaching the crop, either via a detachment movement, or stem cutting by a specially designed gripper/cutter end-effector. However, such unimanual solutions cannot be applied for sensitive crops and cluttered environments such as grapes, where obstacles may occlude the stem, leaving no space for the cutter's placement. In such cases, the solution would require a bimanual robot that visually unveils the stem, while manipulating the grasped crop to create cutting affordances. Considering grapes vertical trellis setups, a dual-arm coordinated motion control methodology is proposed in this work for reaching a stem precut state. The camera equipped arm with the cutter reaches the stem, visually unveiling it, while the second arm moves the grasped grape toward the surrounding free-space, facilitating its stem cutting. In-lab experimental validation and extensive evaluation in a real vineyard with the BACCHUS bimanual harvesting platform demonstrate the performance of the proposed approach.