A Palm-Shape Variable-Stiffness Gripper Based on 3D-Printed Fabric Jamming

Abstract

Soft grippers have excellent adaptability for a variety of objects and tasks. Jamming-based variable stiffness materials can further increase soft grippers' gripping force and capacity. Previous universal grippers enabled by granular jamming have shown great capability of handling objects with various shapes and weight. However, they require a large pushing force on the object during gripping, which is not suitable for very soft or free-hanging objects. In this paper, we create a novel palm-shape anthropomorphic variable-stiffness gripper enabled by jamming of 3D printed fabrics. This gripper is conformable and gentle to objects with different shapes, requires little pushing force, and increases gripping strength only when necessary. We present the design, fabrication and performance of this gripper and tested its conformability and gripping capacity. Our design utilizes soft pneumatic actuators to drive two wide palms to enclose objects, thanks to the excellent conformability of the structured fabrics. While the pinch force is low, the palm can significantly increase stiffness to lift heavy objects with a maximum gripping force of 17 N and grip-to-pinch force ratio of 42. We also explore different variable-stiffness materials in the gripper, including sheets for layer jamming, to compare their performances. We conduct gripping tests on standard objects and daily items to show the great capacity of our gripper design.

The Enhanced Adaptive Grasping of a Soft Robotic Gripper Using Rigid Supports

“…A bending performance comp ison test and lifting force measurement test were conducted to verify the bending cur design and the rigid supports design. The rigid supports increase the lifting force of t [3,6,7,11,20,21]. Our work is plotted according to 3.4. lifting force measurement, which is highlighted in a yellow star.…”

Enhanced Dendrite Resistance in Reversible Electrochemical Pneumatic Batteries with Nanoimprinted Nanowire Anodes for Jamming Robots

“…The gripper fabrication method is mentioned in our previously published paper [24]. To fabricate the gripper, first, the variable-stiffness materials-based fabric is designed by incorporating structured fabrics known as 'European 4 in 1', as shown in Figure 3a, which resemble chain mail and are integrated into the palm part [25].…”

“…For detailed insights into the performance and specifications of our design, please refer to our comprehensive paper on the subject. [24].…”

“…We demonstrate the utility of our REPB as a quiet, efficient source of both high pressure and a vacuum for the palm-shaped variable-stiffness gripper based on 3D-printed fabric as highlighted in Figure 11. The details of this gripper are shown in our previous paper [24]. Briefly, this gripper achieves a maximum gripping force of 17 N. Due to the discrete nature of the fabrics, our gripper conforms well to varied shapes, enhancing its utility.…”

Variable stiffness soft robotic gripper: design, development, and prospects

“…By altering the geometric structure and interplay of components during the robot's operation, the force characteristics of the structure are modified, thus enabling changes in stiffness. Zhao and Wang [154] and Li et al [126] achieved variable stiffness by introducing disruptions in 3Dprinted fabric, resulting in grippers that exhibit compliant and gentle properties when interacting with objects of various shapes. These grippers require minimal manipulation force and can increase grasping strength when necessary, achieving a humanoid-like variable stiffness.…”