Printable Bistable Structures for Programmable Frictional Skins of Soft-bodied Robots

Soft robots made of flexible materials are highly adaptive, easy to fabricate, and safer to interact with. One of the ways for soft robots to interact with the surrounding environment is through their deformable bodily characteristics including internal body stiffness and external body friction. Though the flexibility of soft-bodied robots has been rigorously studied, the frictional skin of such soft-bodied robots, acting as a mechanical interface between the robot and the environment, remains unexplored. Being able to design the frictional skin will make soft-bodied robots more versatile in environmental navigation, more dexterous in manipulation tasks, and more flexible in haptic feedback. In this paper, we propose a robotic skin that can be programmed dynamically to change the mode of friction. The robotic skin is based on bistable bellow structures that can be switched between two folding states to change the contact points between the robotic skin and the ground. Our robotic skin can dynamically change its anisotropic frictional behavior to add another dimension to the designing space of soft robotics.