Discrete Cosserat Approach for Closed-Chain Soft Robots: Application to the Fin-Ray Finger

The Fin-Ray principle, inspired by the physiology of fish rays, represents the foundation of a large number of robotic devices. However, despite their popularity, there is not any
ad-hoc
theoretical model technique for the analysis of this family of fingers. This lack is the main motivation of the presented work, which provides the mathematical modeling, analysis, and prototyping of a closed-chain Fin-Ray finger. In this scenario, the contribution of this article is twofold. At one end, we provide a general discrete Cosserat approach for the modeling of closed-chain soft robots which shares the geometrical structure of the rigid robotics counterpart. On the other end, the approach is employed to explore the family of Fin-Ray effect fingers. Finally, an improved design, which is able to conform to contacting surfaces, while maintaining stiffness out of its grasping plane, is fabricated and its performances are compared to those of a previously proposed prototype.