A design and fabrication approach for pneumatic soft robotic arms using 3D printed origami skeletons

Abstract

Soft robots which employ materials with inherent compliance have demonstrated great potential in a variety of applications such as manipulators, medical tools and wearable devices. This paper presents an origami-folding inspired design and fabrication approach for developing semi-soft robotic arms. The approach starts from a conceptual design by identifying foldable origami structures. This is followed by the kinematic modelling of the selected origami skeleton with base folds of thick panels and flexible hinges. The final step realizes the design by 3D printing the skeleton and laminating the skeleton to flexible membranes on a heated vacuum table. Following the proposed approach, a foldable origami tube structure is designed, modelled and used as the exoskeleton for a pneumatic semi-soft robotic arm. Prototypes are developed by laminating a pair of 3D printed thermoplastic polyurethane (TPU) origami skeleton structures with TPU fabric film. The soft arm is actuated by a vacuum pump and its performances is evaluated through quasi-static tests. Experimental results show that the soft robotic arm achieves a maximum contraction ratio of 47.53% providing 23.463 N axial tension force when applying a regulated negative pressure of -1 bar. Two extensible and foldable pneumatic arms are integrated on a micro aerial vehicle (MAV) to obtain a platform with the potential of aerial manipulation capabilities in confined and hard to reach areas.