Here is a snake inspired robot with a soft actuator made with kirigami that can crawl on the ground without rigid parts. Harvard SEAS researchers have developed an untethered version of this with control, sensors, and power supply packed into a tiny tail.
The team experimented with triangular, circular, and trapezoidal shapes. As they explain:
As the robot stretches, the flat kirigami surface is transformed into a 3D-textured surface, which grips the ground just like snake skin… When the actuator expands, the kirigami cuts pop-out, forming a rough surface that grips the ground. When the actuator deflates, the cuts fold flat, propelling the crawler forward.