A cockroach robot, which squeezes through cracks

A cockroach robot, which squeezes through cracks

University of California, Berkeley, scientists say that cockroaches can quickly squeeze through the tiniest cracks are well justified.

Not only can they squish themselves to get into one-tenth-of-an-inch crevices, but once inside they can run at high speed even when flattened in half.

The UC Berkeley study of how American cockroaches (Periplaneta americana) penetrate the tightest joints and seams in less than a second is indeed crawly.

What the researchers found has inspired a robot that can rapidly squeeze through cracks, a new capability for search-and-rescue in rubble resulting from tornados, earthquakes and explosions.

It s very challenging, because with search and rescue if you want to send a robot to find someone on building rubble, often the gaps are smaller than the robots themselves, Chen Li, postdoctoral researcher in the UC Berkeley department of integrative biology, and electrical engineering and computer science said. The majority of the techniques to help robots navigate failed.

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 Kaushik Jayaram, who recently obtained his Ph.D. from UC Berkeley and is now a postdoctoral fellow at Harvard University.


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 Robert Full, a professor of integrative biology at UC Berkeley.

Mark Cutkosky, professor of mechanical engineering at Stanford University and an expert in small bio-inspired robots, had earlier commented on a similar study that We have had small running robots for a number of years. However, while they can go quite fast on smooth surfaces, they perform poorly in comparison to small animals in rough or cluttered terrain.

Jayaram built the model robot using an origami-like manufacturing technique, now available as an inexpensive kit made by Dash Robotics -- a commercial spin-off from previous robotic work at UC Berkeley. Now, more robust versions will be needed for real-world testing.

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.

Over the past three decades, Full and students in his Poly-PEDAL lab have studied how animals walk, run, jump, glide, crawl and slither to understand the basic biomechanical principles that underlie locomotion, and that can be used to design better robots. Their findings have inspired robots with legs like those of cockroaches and crabs as well as sticky feet like those of geckos. Full, 25 years ago, discovered that American cockroaches can run on two legs -- a feat certified by the Guinness Book of World Records -- and can achieve a speed of nearly 5 feet per second, or 50 times their body length per second.

Using a high-speed camera, 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.

Jayaram is now testing all parts of the cockroach to determine their mechanical properties and their role in the bugs' creepy crawling.

A cockroach robot, which squeezes through cracks