Research on gecko tails presents unique movement applicable to robotics

Photo of the gecko robot
Andre Wee/Courtesy
A team of researchers observed gecko landing techniques and constructed robots that mimicked gecko tails, as the study aims to improve how aerial robots land on vertical surfaces.

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Seven meters above the ground, Max Planck research group leader Ardian Jusufi observed a gecko glide off a tree and crash headfirst into another tree at 13 miles per hour.

Slamming into the tree, the gecko’s body arced in an extreme backbend, yet it didn’t fall off — it pressed its hind legs and tail onto the surface and righted itself. Campus integrative biology professor Robert Full and Jusufi, his former doctoral student, worked with two other scientists, University of Surrey lecturer Robert Siddall and former campus doctoral student Greg Byrnes, to research these unique gecko tail maneuvers and their applications in robotics.

“It’s a very exciting study that you go all the way from being in the rainforest and doing animal locomotion observations, all the way to soft robotics,” Jusufi said. “This is the first time for us, at least, that we were able to go that entire range.”

As part of the study, Jusufi conducted field research at a wildlife reserve rainforest in Singapore over several years.  There, he looked at gecko landing techniques, created mathematical models mapping their rebounding motions and built tailed robots that mimicked the gecko tails.

While geckos do not have specialized traits for gliding, they are able to jump from tree to tree with the help of their tail maneuvers. Once their head and upper legs smash into the tree, their tail dissipates the energy that their back legs otherwise could not have absorbed, helping them stay on the tree and avoid injury, according to Jusufi.

“We found that this tail is quite useful for reducing the forces it experiences at the rear legs, but overall it really extends the window through which impact energy is dissipated,” Jusufi said.

After creating a mathematical model to confirm the tail’s importance in helping geckos land, Jusufi and his team built a gecko-like soft 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 upon landing and confirmed their hypothesis that the tail helps the gecko avoid falling.

Their findings can improve how aerial robots land on vertical surfaces, which can be especially useful as a backup solution when a robot encounters issues like wind, according to Jusufi. However, while engineers can feel compelled to optimize robots for specific tasks, Full suggests continually learning from nature.

“(Organisms) can’t really be optimized to do just one thing, and that fits with the notion of evolution as really not being optimizing (but) being just good enough,” Full said. “You can’t design new structures each time to do a new thing. You’re going to have to do the same thing that evolution did — adapt the structures you have to do more than one thing.”

Gecko tails require additional research, according to Full, who is currently working with another student to research how gecko tail techniques can help fallen robots right themselves and create super agile robots.

While studying geckos may seem “crazy,” such research can yield critical discoveries, according to Full.

“It’s important to always remind the public that you never know where curiosity-based research will lead you,” Full said. “You never know what secrets different creatures hold.”

Contact Cindy Liu at [email protected], and follow her on Twitter at @_CindyLiu_.

Correction(s):
A previous version of this article’s photo caption incorrectly stated that UC Berkeley researchers constructed robots that mimicked gecko tails. In fact, these robots were constructed at Max Planck, not by UC Berkeley researchers.