Robotic Harvesting of Delicate Fruit: Design and Implementation of an Under-Actuated Disturbance-Resistant Gripper
jianguo wang, Jihao Li, Jituo Li, Xiaoqiang Du, Huixu Dong
AI summary
Problem
Existing harvesting grippers struggle with diverse fruit morphologies, require precise positioning, and lack resilience to external disturbances like wind, often causing fruit damage or operational failure.
Approach
The gripper first stabilizes the fruit by enclosing its stem without cutting it, then uses a differential mechanism with a force distribution constraint unit to safely allocate a single motor’s power between grasping and shearing actions.
Key results
- Novel stem-enclosure harvesting strategy for pre-grasping stabilization
- Single-actuator under-actuated design with auxiliary locking and grasping coupling mechanism
- Adjustable force distribution constraint unit for damage-free grasping across varying fruit firmness
- Experimental validation demonstrating high success rates and fruit integrity under environmental disturbances
Why it matters
Enables reliable, low-cost automation for delicate fruit harvesting in unstructured outdoor environments, advancing smart agriculture and reducing crop loss.
Abstract
Agricultural harvesting grippers have emerged as a pivotal technology in the evolution of smart agriculture, enhancing efficient fruit collection. Existing grippers frequently fail to accom- modate the diverse morphologies of fruits. Moreover, achieving stable grasping under external disturbances, such as natural wind, remains a significant challenge. To mitigate these limitations, we present a novel under-actuated gripper for fruit harvesting, along- side the formulation of innovative harvesting strategies aimed at optimizing both the harvest success rate and fruit integrity. Firstly, a strategy is developed to promote the success rate of harvesting operations under disturbance. The harvesting strategy involves stabilizing the fruit by enclosing the stem, followed by grasping and severing the stem to detach the fruit. Secondly, we propose an auxiliary locking and grasping coupling mechanism, which employs a single actuator to drive all gripper components, thereby reducing both cost and control complexity. Thirdly, a force dis- tribution constraint unit is incorporated to allocate the actuator’s power between grasping and shearing actions, enabling regulation of the grasping force to protect the fruit. Finally, the performance of the gripper is assessed through a series of rigorous experiments on fruits with diverse sizes, textures, and surface characteristics, demonstrating its superior efficacy in preserving fruit integrity during real-world harvesting scenarios.