JAMMit! Monolithic 3D-Printing of a Bead Jamming Soft Pneumatic Arm

TL;DR

This paper presents a simple, monolithic 3D-printing method for a soft pneumatic arm with bead jamming, enhancing stiffness while maintaining flexibility, demonstrated through experimental characterization and a switch-toggling task.

Contribution

It introduces a novel monolithic printing technique for a bead-jamming soft pneumatic arm, integrating a tendon-driven spine for improved stiffness and range of motion.

Findings

The arm's stiffness can be effectively controlled via jamming policies.

Experimental results show a trade-off between range of motion and stiffness.

The design successfully performs a switch-toggling task, demonstrating practical utility.

Abstract

3D-printed bellow soft pneumatic arms are widely adopted for their flexible design, ease of fabrication, and large deformation capabilities. However, their low stiffness limits their real-world applications. Although several methods exist to enhance the stiffness of soft actuators, many involve complex manufacturing processes not in line with modern goals of monolithic and automated additive manufacturing. With its simplicity, bead-jamming represents a simple and effective solution to these challenges. This work introduces a method for monolithic printing of a bellow soft pneumatic arm, integrating a tendon-driven central spine of bowl-shaped beads. We experimentally characterized the arm's range of motion in both unjammed and jammed states, as well as its stiffness under various actuation and jamming conditions. As a result, we provide an optimal jamming policy as a trade-off between preserving the range of motion and maximizing stiffness. The proposed design was further demonstrated in a switch-toggling task, showing its potential for practical applications.