Bimanual crop manipulation for human-inspired robotic harvesting

TL;DR

This paper presents a bimanual robotic manipulation method inspired by human harvesting techniques, enabling robots to handle sensitive crops in cluttered environments by coordinating dual-arm motions for stem unveiling and cutting.

Contribution

It introduces a novel dual-arm motion control approach for crop harvesting, addressing limitations of unimanual systems in occluded and cluttered vineyard scenarios.

Findings

Successful lab experiments with UR5e arms demonstrate effective stem unveiling and cutting.

The methodology improves harvesting capability in complex environments.

Enhanced coordination reduces crop damage during robotic harvesting.

Abstract

Most existing robotic harvesters utilize a unimanual approach; a single arm grasps the crop and detaches it, either via a detachment movement, or by cutting its stem with a specially designed gripper/cutter end-effector. However, such unimanual solutions cannot be applied for sensitive crops and cluttered environments like grapes and a vineyard where obstacles may occlude the stem and leave no space for the cutter's placement. In such cases, the solution would require a bimanual robot in order to visually unveil the stem and manipulate the grasped crop to create cutting affordances which is similar to the practice used by humans. In this work, a dual-arm coordinated motion control methodology for reaching a stem pre-cut state is proposed. The camera equipped arm with the cutter is reaching the stem, unveiling it as much as possible, while the second arm is moving the grasped crop towards the surrounding free-space to facilitate its stem cutting. Lab experimentation on a mock-up vine setup with a plastic grape cluster evaluates the proposed methodology, involving two UR5e robotic arms and a RealSense D415 camera.