Seven meters above the ground, the leader of the Max Planck research group, Ardian Jusufi, observed a gecko slip from a tree and crash headfirst into another tree at 13 miles per hour.
Crashing against the tree, the gecko’s body arched into an extreme backbend, but it didn’t fall – it squeezed its hind legs and tail to the surface and straightened up. Campus Integrative Biology professor Robert Full and Jusufi, his former doctoral student, worked with two other scientists, University of Surrey professor Robert Siddall and former campus doctoral student Greg Byrnes, to research these unique tail maneuvers of geckos and their applications in robotics.
“It’s a very exciting study that you go from the rainforest to observing animal locomotion, to soft robotics,” Jusufi said. “This is the first time for us, at least, that we have been able to go through this whole range.”
As part of the study, Jusufi conducted field research in a tropical forest wildlife reserve in Singapore for several years. There, he examined gecko landing techniques, created mathematical models mapping their bounce motions, and built tail robots that mimicked gecko tails.
Although geckos do not have specialized traits for gliding, they are able to leap from tree to tree using their tail maneuvers. Once their head and upper legs crash into the tree, their tail dissipates energy that their hind legs might not otherwise have been able to absorb, helping them stay on the tree and avoid injury, according to Jusufi.
“We have found that this tail is very useful in reducing the forces it is subjected to at the rear legs, but overall it really extends the window through which impact energy is dissipated,” said Jusufi.
After creating a mathematical model to confirm the importance of the tail in helping geckos land, Jusufi and his team built a soft gecko-like robot that allowed them to test their hypothesis in the lab. The robot allowed specific measurements of the forces experienced by different parts of the gecko during landing and confirmed their hypothesis that the tail helps the gecko avoid falling.
Their findings may improve the way aerial robots land on vertical surfaces, which can be particularly useful as a fallback when a robot encounters problems like wind, according to Jusufi. However, while engineers may feel pressured to optimize robots for specific tasks, Full suggests continually learning from nature.
“(Organisms) can’t really be optimized to do a single thing, and that fits the notion of evolution as really not being optimized (but) just good enough,” Full said. “You can’t design new structures every time to do something new. You’re going to have to do the same thing evolution did: adapt structures, you have to do more than one thing.
Gecko tails need further research, according to Full, who is currently working with another student to research how gecko tail techniques can help fallen robots straighten up and create super agile robots.
While studying geckos may seem “crazy,” such research can lead to critical findings, according to Full.
“It’s important to always remind the public that you never know where curiosity-based research will take you,” Full said. “You never know what secrets the different creatures hold.”
Contact Cindy Liu at [email protected], and follow her on Twitter at @_CindyLiu_.
An earlier version of the caption for the photo in this article incorrectly stated that UC Berkeley researchers had built robots that mimicked gecko tails. In fact, these robots were built at Max Planck, not by researchers at UC Berkeley.