Probe-to-Grasp Manipulation Using Self-Sensing Pneumatic Variable-Stiffness Joints

Fuente: arXiv
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Auteurs principaux: Tran, Ngoc Duy, Fan, Yeman, Dai, Feng, Nguyen, Khang, Nguyen, Anh, Ly, Hoang Hiep, Ta, Tung D., Chiba, Shigeru
Format: Preprint
Publié: 2026
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author Tran, Ngoc Duy
Fan, Yeman
Dai, Feng
Nguyen, Khang
Nguyen, Anh
Ly, Hoang Hiep
Ta, Tung D.
Chiba, Shigeru
author_facet Tran, Ngoc Duy
Fan, Yeman
Dai, Feng
Nguyen, Khang
Nguyen, Anh
Ly, Hoang Hiep
Ta, Tung D.
Chiba, Shigeru
contents Grasping deformable objects with varying stiffness remains a significant challenge in robotics. Estimating the local stiffness of a target object is important for determining an optimal grasp pose that enables stable pickup without damaging the object. This paper presents a probe-to-grasp manipulation framework for estimating the relative stiffness of objects using a passive soft-rigid two-finger hybrid gripper equipped with self-sensing pneumatic variable-stiffness joints. Each finger of the gripper consists of two rigid links connected by a soft pneumatic ring placed at the joint, enabling both compliant interaction and controllable joint stiffness via internal pressurization. By measuring the pressure inside the pneumatic ring, we can estimate the interaction force during contact. Building on this, we propose a practical probing strategy to infer relative object stiffness by correlating the estimated normal force with known gripper closing displacement. We validate the self-sensing model through stiffness characterization experiments across bending angles and pressure ranges, and demonstrate stiffness-aware probing-and-grasping in real-life applications: selecting grasp locations on fruits with spatially varying stiffness. The proposed system offers a minimal, low-cost sensing approach for stiffness-aware soft manipulation while retaining probing and grasping capability.
format Preprint
id arxiv_https___arxiv_org_abs_2603_27808
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Probe-to-Grasp Manipulation Using Self-Sensing Pneumatic Variable-Stiffness Joints
Tran, Ngoc Duy
Fan, Yeman
Dai, Feng
Nguyen, Khang
Nguyen, Anh
Ly, Hoang Hiep
Ta, Tung D.
Chiba, Shigeru
Robotics
Grasping deformable objects with varying stiffness remains a significant challenge in robotics. Estimating the local stiffness of a target object is important for determining an optimal grasp pose that enables stable pickup without damaging the object. This paper presents a probe-to-grasp manipulation framework for estimating the relative stiffness of objects using a passive soft-rigid two-finger hybrid gripper equipped with self-sensing pneumatic variable-stiffness joints. Each finger of the gripper consists of two rigid links connected by a soft pneumatic ring placed at the joint, enabling both compliant interaction and controllable joint stiffness via internal pressurization. By measuring the pressure inside the pneumatic ring, we can estimate the interaction force during contact. Building on this, we propose a practical probing strategy to infer relative object stiffness by correlating the estimated normal force with known gripper closing displacement. We validate the self-sensing model through stiffness characterization experiments across bending angles and pressure ranges, and demonstrate stiffness-aware probing-and-grasping in real-life applications: selecting grasp locations on fruits with spatially varying stiffness. The proposed system offers a minimal, low-cost sensing approach for stiffness-aware soft manipulation while retaining probing and grasping capability.
title Probe-to-Grasp Manipulation Using Self-Sensing Pneumatic Variable-Stiffness Joints
topic Robotics
url https://arxiv.org/abs/2603.27808