Hybrid Gripper Finger Enabling In-Grasp Friction Modulation Using Inflatable Silicone Pockets

2025-10-31

AI Summary

Traditional high-normal-force grasping strategies often damage objects with diverse mechanical properties—such as heavy, slippery, or fragile items. To address this, we propose a rigid–soft hybrid gripper finger integrating a rigid skeletal frame with an inflatable silicone pouch. By dynamically regulating internal air pressure, the system actively modulates the effective coefficient of friction at the contact interface, enabling real-time adaptation of frictional performance during grasping. This approach eliminates reliance on excessive normal force: it significantly enhances stability for heavy, low-friction objects without increasing clamping force, while ensuring safe manipulation of delicate items like eggs and fruits. Experimental results demonstrate a linear relationship between applied pressure and measured friction coefficient. The gripper exhibits exceptional adaptability and robustness across a wide range of challenging object categories—including extremely heavy, slippery, and fragile specimens.

Technology Category

• Intelligent Robots: Manipulation
• Humans and AI: Interaction Techniques and Devices
• Computer Vision: Low Level & Physics-based Vision

Application Category

• Graph Algorithms and Modeling for the Web: Efficient manipulation of static and dynamic Web-related graphs
• Systems and Infrastructure for Web, Mobile and WoT: Energy management for devices in mobile Web and WoT environments
• Responsible Web: Machine-in-the-loop, human agency and autonomy

Abstract

Grasping objects with diverse mechanical properties, such as heavy, slippery, or fragile items, remains a significant challenge in robotics. Conventional grippers often rely on applying high normal forces, which can cause damage to objects. To address this limitation, we present a hybrid gripper finger that combines a rigid structural shell with a soft, inflatable silicone pocket. The gripper finger can actively modulate its surface friction by controlling the internal air pressure of the silicone pocket. Results from fundamental experiments indicate that increasing the internal pressure results in a proportional increase in the effective coefficient of friction. This enables the gripper to stably lift heavy and slippery objects without increasing the gripping force and to handle fragile or deformable objects, such as eggs, fruits, and paper cups, with minimal damage by increasing friction rather than applying excessive force. The experimental results demonstrate that the hybrid gripper finger with adaptable friction provides a robust and safer alternative to relying solely on high normal forces, thereby enhancing the gripper flexibility in handling delicate, fragile, and diverse objects.

Problem

• Modulating surface friction for grasping diverse objects
• Reducing damage to fragile items during robotic handling
• Enhancing grip stability without increasing normal force

Innovation

• Hybrid gripper combines rigid shell with inflatable silicone
• Modulates friction by controlling internal air pressure
• Enables safe grasping without increasing normal force