FifoBots: Foldable Soft Robots for Flipping Locomotion

In this work, we design a type of soft robots for flipping locomotion, called the FifoBots. Different from most of the current soft robots that perform crawling, rolling, or jumping locomotion, the proposed FifoBots can flip forward and backward like a piece of self-foldable paper. The FifoBots have simple actuation and avoid complicated balance control. This article presents the principle and analysis of the flipping locomotion as well as the prototypes and experiments of the FifoBots. Two schemes of the flipping locomotion are proposed, and each scheme has the linear and quadrilateral morphologies, enabling the straight and biaxial movements, respectively. The movement performance in each stage of the flipping locomotion is analyzed oriented to the parameter design. The prototypes are constructed by using customized bidirectional Curl pneumatic artificial muscles as the flexible hinges and 3D printed parts as the rigid limbs. Feasibility and adaptability of the proposed robots are validated by locomotion experiments. The FifoBots have potential applications in space exploration in complicated environments with slope, gap, obstacle, or rocky terrain.