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Abstract In this paper, we present a novel compliant robotic gripper with three variable stiffness fingers. While the shape morphing of the fingers is cable-driven, the stiffness variation is enabled by layer jamming. The inherent flexibility makes compliant gripper suitable for tasks such as grasping soft and irregular objects. However, their relatively low load capacity due to intrinsic compliance limits their applications. Variable stiffness robotic grippers have the potential to address this challenge as their stiffness can be tuned on demand of tasks. In our design, the compliant backbone of finger is made of 3D-printed PLA materials sandwiched between thin film materials. The workflow of the robotic gripper follows two basic steps. First, the compliant skeleton is driven by a servo motor via a tension cable and bend to a desired shape. Second, upon application of a negative pressure, the finger is stiffened up because friction between contact surfaces of layers that prevents their relative movement increases. As a result, their load capacity will be increased proportionally. Tests for stiffness of individual finger and load capacity of the robotic gripper are conducted to validate capability of the design. The results showed a 180-fold increase in stiffness of individual finger and a 30-fold increase in gripper’s load capacity.
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A High Performance Pneumatically Actuated Soft Gripper Based on Layer Jamming
Abstract This article presents a novel soft robotic gripper with a high payload capacity based on the layer jamming technology. Soft robots have a high adaptability, however suffer a low payload capacity. To overcome these conflicting challenges, here we introduce a 3D printed multi-material gripper that integrates jamming layers for enhancing payload capacity. By inflating the internal air chamber with positive pressure, the finger can be actuated to a large bending angle for adapting complex shapes. Layers of jamming sheets are bounded on the finger structure and are then sealed inside a vacuum bag. When a high payload is desired, air inside the vacuum bag is drawn out and a negative air pressure is applied to the jamming layers, which leads to the gripper locked at the actuated shape. To evaluate the performance of the gripper, we conducted extensive tests including actuation, stiffness variation, typical payload capacity, and adaptability. The results show that our gripper is not only highly adaptable just like most soft grippers but also more importantly capable of grasping heavy (about 6–10 kg) objects comparable to rigid-body counterparts.
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- Award ID(s):
- 2019648
- PAR ID:
- 10557927
- Publisher / Repository:
- ASME
- Date Published:
- Journal Name:
- Journal of Mechanisms and Robotics
- Volume:
- 15
- Issue:
- 1
- ISSN:
- 1942-4302
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1115/1.4053857
