Contact-Triggered Sequential Grasping With an HSA-Driven Underactuated Gripper for Delicate Produce
Xiaoqian Zhang, Mario Baggetta, Cristina Piazza, and Giovanni Berselli IEEE/ASME Transactions on Mechatronics, vol. 31, no. 4, pp. 4828-4836, 2026. DOI: 10.1109/TMECH.2026.3696423
A passive differential compensates for target offset, while HSA fingers transition from pinching to enclosure after contact.
Design animation and prototype footage. Quantitative findings are reported in the paper and refer to its specific test conditions.
Who may find this useful
Researchers developing underactuated hands, adaptive end-effectors, and robotic handling of delicate produce.
What the mechanism contributes
Passive target tracking after early contact
Pinching-to-enclosure transition through torque redirection
A single actuator drives both mechanical subsystems
Evidence & scope
Finite-element analysis and benchtop experiments evaluate offsets, object sizes, pull-out behavior, pinch-only operation, and side-entry grasping. These are prototype-level results; field harvesting and biological bruise reduction are not established by this demonstration.
Abstract
A main challenge in agri-tech lies in robotic handling and harvesting of delicate produce. Traditional end-effectors struggle to balance grip stability, adaptability to irregular items, and bruise mitigation. In this work, a soft gripper based on handed shearing auxetic (HSA) structures is presented. The gripper adopts a dual-module architecture composed of a target tracking system (TTS) and a pinch and grasp system (PGS). A passive tendon-driven differential shifts the grasping center after early contact, compensating for target misalignment without active sensors. The PGS employs HSA units to achieve transition from parallel pinching to bending-based enclosure through contact-induced torque redirection. Both modules share a single actuator and preserve a minimal transmission architecture. Finite element simulations and response surface exploration identify key stiffness and geometric parameters, guiding the rigid-body synthesis of the TTS and actuator selection. Experiments on objects with varying offsets, diameters, and pull-out conditions, including pinch-only and side-entry tests, assess the ability to self-center, pinch, and enclose without additional control layers. The results indicate that HSA actuation combined with passive differentials can provide a compact mechanism-level solution for produce-oriented grasping under representative benchtop conditions.
Cite the published paper
@article{Zhang2026gripper3,
title = {Contact-Triggered Sequential Grasping With an HSA-Driven Underactuated Gripper for Delicate Produce},
author = {Xiaoqian Zhang and Mario Baggetta and Cristina Piazza and Giovanni Berselli},
journal = {IEEE/ASME Transactions on Mechatronics},
year = {2026},
doi = {10.1109/TMECH.2026.3696423}
}
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