FOCUS

Video—Roach-like Robots Act Collectively

Physics 11, 45
A collection of simple, self-propelled robots in a flexible and mobile corral can pull the whole group through a narrow space between walls.
A. Deblais et al., Phys. Rev. Lett. (2018)
Robot army. Collections of small, simple bots may someday perform useful tasks like exploration, so researchers want to learn about their basic principles of operation. (See videos below.)

Swarms of insects or populations of microbes can produce surprisingly coordinated phenomena, even though each individual operates with very simple rules. Hamid Kellay of the University of Bordeaux in France and his colleagues have demonstrated similar behavior in roach-like, battery-powered robots that skitter around randomly inside a corral. Previous researchers have also observed self-propelled swarmers in enclosed regions, but Kellay's team documented new forms of collective motion using movable corrals. The ultimate aim of this body of research is to produce small, simple robots that team up for a variety of tasks, such as self-assembly or exploration.

A. Deblais et al., Phys. Rev. Lett. (2018)
Roach-bots in a fixed corral segregate into two populations: one that buzzes around like a gas and another that clusters along the boundary, but individuals continually switch between the two.

The roach-bots used by Kellay and colleagues are commercial toys a few centimeters long that move at speeds of around 30 centimeters per second by vibrating on top of stiff, angled legs. The team showed that when a small number of bots is corralled, they bounce around like a 2D gas of molecules. But above a critical number (which depended on several parameters), some fraction of the bots line up in one or more tight clusters along the corral boundary (see first video). The gas and cluster populations remain in equilibrium, with members of each population continually being exchanged. The researchers also found that the unified pushing of the cluster bots could drive collective motion. By selecting a corral that was both flexible and mobile, they showed that the robot army could push its enclosure smoothly through a narrow aperture or roll it around an obstacle (see second and third videos).

A. Deblais et al., Phys. Rev. Lett. (2018)
In a mobile corral, the bots can collectively drive their enclosure forward and push it through a small hole.
A. Deblais et al., Phys. Rev. Lett. (2018)
The bots can also roll their corral around a curved surface.

This research is published in Physical Review Letters.

–David Ehrenstein

David Ehrenstein is a Senior Editor for Physics.

More Information

  • 2013 video about Harvard research with similar robots in fixed corrals.


Subject Areas

Soft Matter

Related Articles

Simple Additives Make Polar Fluids More Polar
Soft Matter

Simple Additives Make Polar Fluids More Polar

The strong polar nature of bonded molecular pairs called zwitterions boosts the dielectric constants of polar fluids. Read More »

Topology Inside a Liquid Crystal
Soft Matter

Topology Inside a Liquid Crystal

The orientation boundaries in a liquid crystal can be characterized by a topological charge that always sums to one, no matter the shape of the container.   Read More »

Inducing a Curl with a Stretch
Soft Matter

Inducing a Curl with a Stretch

Patterning grooves into the surface of an elastic ribbon can cause the ribbon to curl into a tube shape when it is stretched. Read More »

More Articles