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

TL;DR

This paper introduces a hybrid robotic gripper finger with inflatable silicone pockets that actively modulate surface friction via internal pressure, enabling safer and more versatile handling of diverse objects.

Contribution

The novel hybrid gripper finger combines a rigid shell with an inflatable silicone pocket to dynamically control friction, improving object handling without excessive force.

Findings

Friction increases proportionally with internal pressure.

Able to lift heavy and slippery objects safely.

Reduces damage to fragile objects during grasping.

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.