Tiled Auxetic Cylinders for Soft Robots

Compliant structures allow robots to overcome environmental challenges by deforming and conforming their bodies. In this paper, we investigate auxetic structures as a means of achieving this compliance for soft robots. Taking a tiling based approach, we fabricate 3D printed cylindrical auxetic structures to create tiled auxetic cylinders (TACs). We characterise the relative stiffness of the structures and show that variation in behaviour can be achieved by modifying the geometry within the same tiling family. In addition, we analysed the equivalent Poisson's ratio and found the range between the investigated designs to span from -0.33 to -2. Furthermore, we demonstrate a conceptual application in the design of a soft robot using the auxetic cylinders. We show that these structures can reactively change in shape, thereby reducing the complexity of control, with potential applications in confined spaces such as the human body, or for exploration through unpredictable terrain.