Pneumatic morphorods: curvilinear shape morphing and stability*

Flexible slender bodies are boundless in nature as versatile tools for locomotion: e.g. elephant trunks, octopus arms, cucumber tendrils. These structures have inspired an array of soft-robotic structures that bend and twist. The use of these tools outside of academic settings is still limited in part due to complex modeling of structures in 3D environment with non-trivial loads and shapes. Here we leverage bubble casting as a means to build linear actuators with controllable and tunable bending. To generate 3-D curves we cast planar curves that bend out-of-plane when inflated to generate torsion. We solve the inverse problem of mapping a 3-D curve to an initial in-plane curve using a physical analog to the Bishop Frame. We explore the mechanical response of the curves when subject to external loads and geometric constraints.