There are actually a number of ways a long tubular robot without wheels can travel, all of which are utilized by snakes in different situations. These vehicles are typically seen as useful for pipe inspections and disaster recovery. A snake-form is also a popular choice for experimenting with self-reconfiguring robot swarms.
Slithering locomotion actually breaks down into at least three dominant modes: Friction leverage sliding from large bends, as in a sidewinder, small muscular pulses known as peristalsis (often several simultaneously), as in worms, and lifting up the end of the vehicle completely to advance, as in inchworms.
- Snakes on a Plane! That are Actually Laser-Wielding Robots - The Atlantic