Tube-crawling soft robots driven by multistable buckling mechanics

Abstract We present a class of soft robots, which can self-adaptively move forward and backward along a tube with an arbitrary cross-section. The soft robot consists of a linear actuator, a motor, and a set of connected soft elastic ribbons, arranged longitudinally on the robot’s circumference. These ribbons, with strategically designed creases and linkages, can be bended and twisted into different three-dimensional configurations via nonlinear mechanical buckling, thereby achieving forward and backward motions by simply using different actuation sequences of the two actuators. Our approach, based on multistable buckling mechanics and loading-sequence strategy, is thus fundamentally different from existing platforms such as “inchworm” and “earthworm” peristaltic robots, which require at least three actuators and not utilize multiple distinct buckling modes for locomotion. Our design may shed light on the development of new locomotions, and may serve as an alternative for designing soft robots for pipe inspection, repairing, and other applications.