The Jamming Donut: A Free-Space Gripper based on Granular Jamming

TL;DR

This paper introduces a novel hybrid soft gripper combining pneumatic deformation and granular jamming in free space, enabling adaptable and strong grip capabilities for fruit harvesting and object manipulation.

Contribution

It presents the first design and characterization of a free-space granular jamming gripper that integrates pneumatics for shape conformity and jamming for enhanced grip strength.

Findings

Achieves significantly larger retention forces than pure pneumatic grippers.

Demonstrates adaptability to various shapes and sizes of objects.

Successfully picks a broad range of real fruits.

Abstract

Fruit harvesting has recently experienced a shift towards soft grippers that possess compliance, adaptability, and delicacy. In this context, pneumatic grippers are popular, due to provision of high deformability and compliance, however they typically possess limited grip strength. Jamming possesses strong grip capability, however has limited deformability and often requires the object to be pushed onto a surface to attain a grip. This paper describes a hybrid gripper combining pneumatics (for deformation) and jamming (for grip strength). Our gripper utilises a torus (donut) structure with two chambers controlled by pneumatic and vacuum pressure respectively, to conform around a target object. The gripper displays good adaptability, exploiting pneumatics to mould to the shape of the target object where jamming can be successfully harnessed to grip. The main contribution of the paper is design, fabrication, and characterisation of the first hybrid gripper that can use granular jamming in free space, achieving significantly larger retention forces compared to pure pneumatics. We test our gripper on a range of different sizes and shapes, as well as picking a broad range of real fruit.