The Bug Ballet Of Jumping Spider Crickets

The latest inspiration for robot design lurks in the dark corners of damp basements.

Engineering students and their professor at Johns Hopkins University have spent more than eight months unraveling the hopping skills, airborne antics, and safe-landing patterns of the incredibly athletic spider cricket.

The team thinks non-human creatures may be the best models in designing mechanical helpers to carry out certain important tasks. Figuring out how critters move, they say, could lead to planetary rovers that crawl like caterpillars or winged drones that hover like hummingbirds.

Using high-speed video cameras, the team collected clues about how the tiny, wingless spider crickets can somehow leap a distance equal to about 60 times their body length. That’s a feat far beyond what any human track star could accomplish.

To replicate the cricket’s leap, an adult human would have to jump 300 feet—nearly the length of a football field. And, most times, spider crickets manage to land safely on their feet.

How, the researchers wanted to know, can these tiny bugs accomplish this?

Tiny Limbs in Motion

Says Emily Palmer, a sophomore mechanical engineering major in the university’s Whiting School of Engineering who is doing much of the testing:

“Because they don’t have wings, the main things they use during their ‘flight’ to stabilize their posture is their limbs. We’re looking at the way the spider crickets move their bodies and move their limbs to stabilize their posture during a jump.”

The knowledge could contribute to the design of tiny, high-jumping robots to travel over rugged, uneven ground, which Palmer says would utilize a more efficient and probably less expensive form of locomotion, compared to flying robots or humans on foot.

To get a clear, close-up view of the crickets’ limbs in action, the team’s three video cameras each snapped 400 frames per second. Then, by slowing down the finished footage, the researchers saw precisely how each spindly insect leg contributed to the amazing leaps and landings.

Rajat Mittal, the mechanical engineering professor who is supervising the research, was startled to see that, in slow-motion, the crickets’ limb movements bore an uncanny resemblance to classical dance.

“These videos have actually been quite eye-opening,” he says, “because it’s only when you slow these critters down that you really start to see the beauty and the intricacy of their movement. The analogy that comes to mind is of a ballerina performing a ballet. It’s a very beautiful, controlled, intricate motion.”

Slow-motion playback confirmed that during the “flight” segment of their jumps, the crickets carefully used their limbs and even perhaps their antennae to stabilize their posture and prepare for a safe landing.

The crickets seek to land on their feet, the researchers say, so that they can quickly be prepared to leap again to escape any predators that are waiting to pounce.

Masters of Aerodynamics

Some of the video footage yielded surprises. The team discovered that as the crickets soared upward during the early part of their jumps, the bugs streamlined their bodies like a projectile to maximize the distance they would travel.

“They really are masters of aerodynamics,” Mittal says.

Captured by the lab’s cameras, this aerial mastery was transferred to computers to create detailed three-dimensional models depicting how each insect’s body parts move during a leap and a touchdown.

Mittal suggests that a new generation of jumping micro-robots modeled on these crickets might someday be able to help look for victims after a powerful earthquake or carry out other tasks without putting humans searchers at risk.

Top Photo: Johns Hopkins