Inflatable Snapping Metamaterials for Next Generation Soft Machines

软机器是由软材料制成的机械装置，通过其身体变形来实现功能。与传统的刚性对应物相比，它们的优势通常体现在交互安全性、适应性和低成本制造方面。软机器可以由弹性充气致动器驱动，根据它们的设计表现出各种各样的运动。类似地，柔性机械超材料的设计是为了实现所需的机械响应，包括复杂的非线性效应，如可逆的卡通不稳定性。事实上，超材料被定义为一种人造材料，它表现出超出其成分的特殊性能。该项目旨在通过设计和制造利用结构超材料的非线性响应的充气式断裂致动器来创建一个新的软机器系列。由于机械超材料响应的高度可调性，新的功能将被编码在结构中，使下一代具有简化控制和体现智能的软机器成为可能。在这项建议中，有三个主要目标。第一个目标是设计和制造一个具有非线性压力-体积曲线的充气式致动器，允许卡通现象。由于简单的充气壳具有线性单调的压力-体积响应（如果没有气球效应），因此将仅由超材料结构引起卡通。第二个目标是开发一种方法来设计简化的控制方案，利用制动器的快速响应。这种方法被称为“形态控制”，因为它利用系统的物理特性来实现控制任务。一个相互连接的执行器阵列将被建模为一个非线性流体网络。将开发一种算法来反演非线性流体网络方程，并根据期望的响应获得系统参数，例如，特定的驱动序列模式。最后，将前面的概念应用于设计和制造一个可以在陆地和水中移动的双模态软机器人演示器。本项目设想的软体机器人将为所有执行器提供单一压力输入，因此，产生运动模式的序列将在形态上受到控制。本提案中设想的新设计和控制原则对于实现具有更高水平具身智能的下一代多功能软机器至关重要。

Soft machines are mechanical devices made of soft materials and perform functions through their bodily deformation. Their benefits over traditional rigid counterparts are typically reported in terms of interaction safety, adaptability and low-cost fabrication. Soft machines can be driven by elastic inflatable actuators, which exhibit a variety of motions according to their design. Similarly, flexible mechanical metamaterials are designed to achieve desired mechanical responses, including complex nonlinear effects such as reversible snap-through instabilities. Indeed, a metamaterial is defined as an artificial material that exhibits special properties beyond the ones of its constituents. This project aims at creating a new family of soft machines by designing and fabricating inflatable snapping actuators that harness the nonlinear response of architected metamaterials. Thanks to the high tunability of the mechanical metamaterial response, novel functionalities will be encoded in the structure, enabling next generation soft machines with simplified control and embodied intelligence. In this proposal, three main objectives are targeted. The first objective is to design and fabricate an inflatable actuator with a nonlinear pressure-volume curve that allows snap-through phenomenon. As a simple inflatable shell has a linear monotonic pressure-volume response (if there are no ballooning effects), the snap-through will be induced solely by the metamaterial architecture. The second objective is to develop a methodology to design simplified control schemes by exploiting the snapping response of the actuators. This approach is named “morphological control”, as it makes use of the physical properties of the system to achieve a control task. An array of interconnected actuators will be modelled as a nonlinear fluidic network. An algorithm will be developed to invert the nonlinear fluidic network equations and obtain the system parameters based on the desired response, e.g., a specific sequenced pattern of actuation. Lastly, the previous concepts will be applied to design and fabricate a bi-modal soft robotic demonstrator that can locomote on land and water. The soft robot envisioned in this project will have a single pressure input for all the actuators and the sequences that create the locomotion patterns will be, therefore, morphologically controlled. The new designs and control principles envisaged in this proposal will be paramount to enable next generation multifunctional soft machines with higher levels of embodied intelligence.