The nonlinear mechanical response of soft materials and slender structures is purposefully harnessed to program functions by design in soft robotic actuators, such as sequencing, amplified response, fast energy release, etc. However, typical designs of nonlinear actuators - e.g. balloons, inverted membranes, springs - have limited design parameters space and complex fabrication processes, hindering the achievement of more elaborated functions. Mechanical metamaterials, on the other hand, have very large design parameter spaces, which allow fine-tuning of nonlinear behaviours. In this work, we present a novel approach to fabricate nonlinear inflatables based on metamaterials and origami (Meta-Ori) as monolithic parts that can be fully 3D printed via Fused Deposition Modeling (FDM) using thermoplastic polyurethane (TPU) commercial filaments. Our design consists of a metamaterial shell with cylindrical topology and nonlinear mechanical response combined with a Kresling origami inflatable acting as a pneumatic transmitter. We develop and release a design tool in the visual programming language Grasshopper to interactively design our Meta-Ori. We characterize the mechanical response of the metashell and the origami, and the nonlinear pressure-volume curve of the Meta-Ori inflatable and, lastly, we demonstrate the actuation sequencing of a bi-segment monolithic Meta-Ori soft actuator.

翻译：软材料和细长结构的非线性力学响应被有目的地利用，通过设计在软体机器人执行器中编程功能，例如序列化、放大响应、快速能量释放等。然而，典型的非线性执行器设计——例如气球、反转膜、弹簧——其设计参数空间有限且制造工艺复杂，阻碍了更精细功能的实现。另一方面，力学超材料具有非常大的设计参数空间，允许对非线性行为进行微调。在这项工作中，我们提出了一种基于超材料和折纸（Meta-Ori）制造非线性充气结构的新方法，该结构可作为整体部件，使用热塑性聚氨酯（TPU）商用线材通过熔融沉积成型（FDM）技术完全3D打印。我们的设计包括一个具有圆柱拓扑结构和非线性力学响应的超材料外壳，以及一个作为气动传输器的Kresling折纸充气结构。我们开发并发布了一个基于可视化编程语言Grasshopper的设计工具，用于交互式设计我们的Meta-Ori。我们表征了超材料外壳和折纸的力学响应，以及Meta-Ori充气结构的非线性压力-体积曲线，最后，我们演示了一个双段整体式Meta-Ori软体执行器的驱动序列。