Anyone who has tried to kill a cockroach knows just how difficult they can be to be to capture. Not only can they squeeze through very narrow gaps, but they can also instantly accelerate to a running speed of approximately 50 body lengths per second. Recently, biologists at the University of California, Berkeley realized that the insects have another escape skill at their disposal. When they get to the edge of a surface such as a table, they can hook it with their rear claws and swing around 180 degrees to land upside down on its underside – a maneuver also performed by geckos. A team of UC Berkeley researchers subsequently did what any of us would do upon gaining that knowledge, and set out to get a robot to perform the action.
When cockroaches perform the maneuver, they run at the edge of the table at full speed, hooking it with both or sometimes even just one claw as they go over. The momentum swings them around like a pendulum, causing them to pull 3-5 gs, or about what we might might experience at the bottom of a bungee jump. When they land on the bottom of the table, 75 percent of their running energy is still intact. This potentially allows them to continue running in the opposite direction, on the underside of the table.
Working in the lab of professor of electrical engineering and computer science Ron Fearing, graduate students started by attaching Velcro to the rear legs of an existing small robot known as DASH. Taking its acronym from Dynamic Autonomous Sprawled Hexapod, DASH is a small six-legged robot that was initially inspired by cockroaches.
In lab tests, DASH ran to the edge of a ramp, on the very edge of which was a strip of Velcro that was paired to the strips on the robot’s back legs. Using this setup, it was able to execute a move quite similar to that performed by the cockroaches and geckos. So, what’s the point?
“Today, some robots are good at running, some at climbing, but very few are good at both or transitioning from one behavior to the other,” said professor of integrative biology Robert Full. “That’s really the challenge now in robotics, to produce robots that can transition on complex surfaces and get into dangerous areas that first responders can’t get into.”
Cockroaches, geckos and DASH can all be seen performing the “ledge flip,” in the video below.