Additive Manufacturing of TPU Pneu-Nets as Soft Robotic Actuators

Soft robots provide the opportunity to handle a diverse range of products, contributing to mass customization in modern production environments. Both, their manufacturing and behavioral modelling are crucial challenges, due to their unique, bio-inspired design, as well as with respect to the elastic materials, which are applied. Commonly, the actuators and grippers of these robots are manufactured in a traditional casting approach, which is both elaborate and requires molding clearances. In this paper, the additive manufacture (AM) of thermoplastic polyurethane (TPU) is investigated in the context of its application as soft robotic components. Compared to other elastic AM materials, TPU reveals superior mechanical properties with regard to strength and strain. By selective laser sintering, pneumatic bending actuators (pneu-nets) are 3D printed as soft robotic case study and experimentally evaluated with respect to deflection over internal pressure. Leakage due to air tightness is observed as a function of minimum wall thickness of the actuators. In an automated production environment, soft robotics can complement the transformation of rigid production systems towards agile and smart manufacturing.