A single fire ant struggles and usually drowns when it tries to cross water. But when a group of fire ants comes to a body of water, they bind together into a makeshift raft that can remain afloat for days. Engineers at the Georgia Institute of Technology have been studying this self-assembling behavior to see if similar behavior can be programmed into robots. The research team discovered that the fire ants’ exoskeletons are moderately hydrophobic. But by linking bodies using mandibles, claws, and adhesive pads that exert forces 400 times greater than their body weight, the ants create a viscous and elastic waterproof fabric.
By tracking individual ants, the researchers determined that all ants follow a simple behavior pattern. Each ant walks in a straight line, ricochetting off the edge of the growing raft, then walking again until attaching itself to an edge. The raft is ready to float in under 100 sec. The raft is also self-healing. If one ant gets removed, another moves in to fill the void.
“The ants are a group of unintelligent units, each acting on a few simple behaviors that let them work together to build complex structures needed to accomplish a task,” says Nathan Mlot, a mechanical engineering grad student. “This is what we want in autonomous robots — to have robots follow a few simple rules to reach an end result.”