Robotic Skins With Integrated Actuation, Sensing, and Variable Stiffness

Soft robots are often designed to accomplish a single function and cannot be repurposed for other tasks. In an effort to create multi-functional robots, researchers have proposed robotic skins, which are flexible, planar substrates with embedded actuation and sensing that can be applied to different soft bodies. By “roboticizing” otherwise inert bodies from their surface, robotic skins can be repurposed to create bespoke soft robots as needed. However, current robotic skins are unable to support their own structure and can only attain a single function in the absence of a host. Here, we present a variable stiffness robotic skin (VSRS), a concept that integrates stiffness-changing capabilities, sensing, and actuation into a single, thin modular robot design. Reconfiguring, reconnecting, and reshaping VSRSs allows them to achieve new functions both on and in the absence of a host body. We demonstrate how a single set of skins with PneuFlex-style pneumatic actuators, a geometrically-patterned polyethylene terepthalate (PET) jamming membrane, and liquid metal-based capacitive sensors can operate as closed-loop locomotion robots while being able to support weight during locomotion, as well as stiffen to hold complex shapes. To highlight the generality of the concept and illuminate the design space, we also test a second embodiment with McKibben actuators and a woven-mesh jamming membrane that can be reconfigured to serve in a manipulation context. We see VSRSs having application as adaptable linkages in larger robots, smart reconfigurable garments, and reconfigurable active structures, thereby allowing the robotic system to adapt to time-varying task requirements.