Robot cockroach swarms could be released to find earthquake victims

For earthquake survivors buried under a pile of rubble a swarm of cockroaches is likely to be the last thing they would want to see.

But the University of California and Harvard University and have developed robot insects which can be released into collapsed buildings to find survivors by squeezing through minute cracks and crevices which are normally out of reach.

To develop the ‘cyber-roaches’ researchers studied the movement of real insects to see how they manage to move quickly even through the smallest of spaces.

They found that cockroaches can squish themselves into a gap of just one tenth of an inch, but still run at high speed when flattened in half, by repositioning their legs out to the side.

"What's impressive about these cockroaches is that they can run as fast through a quarter-inch gap as a half-inch gap, by reorienting their legs completely out to the side," said study leader Dr Kaushik Jayaram, of Harvard University.

"They're about half an inch tall when they run freely, but can squish their bodies to one-tenth of an inch -- the height of two stacked pennies."

Using the roach technique as inspiration, Jayaram designed a simple and cheap palm-sized robot that can splay its legs outward when squashed, then capped it with a plastic shield similar to the tough, smooth wings covering the back of a cockroach.

Called CRAM, for compressible robot with articulated mechanisms, it was able to squeeze into and run through crevices half its height.

"In the event of an earthquake, first responders need to know if an area of rubble is stable and safe, but the challenge is, most robots can't get into rubble," said Professor Robert Full, of University of California, Berkeley.

"But if there are lots of cracks and vents and conduits, you can imagine just throwing a swarm of these robots in to locate survivors and safe entry points for first responders."

"This is only a prototype, but it shows the feasibility of a new direction using what we think are the most effective models for soft robots, that is, animals with exoskeletons.

“Insects are the most successful animals on earth. Because they intrude nearly everywhere, we should look to them for inspiration as to how to make a robot that can do the same."

People watch as rescuers search for bodies in the rubble of a building which collapsed in Bhaktapur near Kathmandu

For more than 30 years, Prof Full’s lab has been studying how animals walk, run, jump, glide, crawl and slither to understand how nature gets round complex problems.

Their findings have inspired robots with legs like those of crabs as well as sticky feet like those of geckos.

Using a high-speed camera, Dr Jayaram filmed roaches running at nearly full speed between plates spaced a quarter-inch apart, less than the thinnest part of a roach's body.

By narrowing the slits, he found that they could slip through slits of one-tenth of an inch if highly motivated.

While squashed, they cannot properly use their feet, so they use the sensory spines on their tibia to push against the floor to move forward.

"They have to use different body parts to move in these spaces, because their legs and feet are not oriented to work properly," Dr Jayaram.

"But they are still capable of generating the large forces necessary for locomotion, which blew my mind."

The research is published in the Proceedings of the National Academy of Sciences.