SoftSnap: Rapid Prototyping of Untethered Soft Robots Using Snap-Together Modules.

Soft robots offer adaptable, safe interactions in complex environments, with the potential for diverse applications, such as mimicking biological motions. One major challenge is designing and prototyping soft robots with varying deformation modes, which can be a time-consuming process. To address this hurdle, reconfigurable modular robots have emerged as a solution, allowing reusable and rapid prototyping into different soft robots. However, balancing simplicity in design with extensive deformation capabilities remains an open problem. Existing reconfigurable soft robotic modules have demonstrated adaptability, often relying on modular stacking to achieve a wide range of deformations. Typically, achieving complex deformations, such as forming a continuous curve, requires multiple modules connected in a chain, as each individual module can only transition between a limited set of predefined deformation states. We introduce SoftSnap modules: snap-together components that enable the rapid assembly of a class of untethered soft robots. Each SoftSnap module integrates computation, motor-driven string actuation, and a flexible thermoplastic polyurethane (TPU)-printed deformable structure, allowing a vast deformation range through different pre-wired string configurations. These modules connect seamlessly with other SoftSnap units or customizable connectors. Demonstrated configurations include starfish-like, brittle star, snake, 3D gripper, and ring-shaped robots, showcasing ease of assembly, adaptability, and functional diversity. The scalable, reconfigurable design of SoftSnap provides researchers with an efficient and flexible platform for rapidly prototyping untethered soft robotic systems.