Robotic Recreation of Mudskippers Sheds New Light on Evolution

Sunday, July 10, 2016

Robotic Recreation of Mudskippers Sheds New Light on Evolution


A new study of African mudskipper, including development of a robotic model inspired by the animal has found the animals needed to use their tails to propel themselves forward. Shedding new light on the evolution of the first terrestrial animals, the work shows that the powerful tails the animals used as fish may have been more important than scientists previously realized. 

A new study could help designers create amphibious robots able to move across granular surfaces more efficiently and with less likelihood of getting stuck in the mud.

The project, published recently in the journal Science involved a multidisciplinary team of physicists, biologists and roboticists from the Georgia Institute of Technology, Clemson University and Carnegie Mellon University. Following a detailed study of the mudskipper, the team developed of a robot model that used the animal’s locomotion techniques. The study also examined flow and drag conditions in representative granular materials, and applied a mathematical model incorporating new physics based on the drag research.

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“Most robots have trouble moving on terrain that includes sandy slopes,” said Dan Goldman, an associate professor in the Georgia Tech School of Physics. “We noted that not only did the mudskippers use their limbs to propel themselves in a kind of crutching motion on sand and sandy slopes, but that when the going got tough, they used their tails in concert with limb propulsion to ascend a slope. Our robot model was only able to climb sandy slopes when it similarly used its tail in coordination with its appendages.”

Using fossil records, scientists have long studied how early land animals may have gotten around, and the new study suggests their tails – which played a key role in swimming as fish – may have helped supplement the work of fins, especially on sloping granular surfaces such as beaches and mudflats.

robot mudskipper

"We were interested in examining one of the most important evolutionary events in our history as animals: the transition from living in water to living on land."
“We were interested in examining one of the most important evolutionary events in our history as animals: the transition from living in water to living on land,” said Richard Blob, alumni distinguished professor of biological sciences at Clemson University. “Because of the focus on limbs, the role of the tail may not have been considered very strongly in the past. In some ways, it was hiding in plain sight. Some of the features that the animals used were new, such as limbs, but some of them were existing features that they simply co-opted to allow them to move into a new habitat.”

The research team recorded how the mudskippers (Periopthalmus barbaratus) moved on a variety of loose surfaces, providing data and video to Goldman’s laboratory. The small fish, which uses its front fins and tail to move on land, lives in tidal areas near shore, spending time in the water and on sandy and muddy surfaces.

The team then applied the principles to a robot model known as MuddyBot that has two limbs and a powerful tail, with motion provided by electric motors. Information from both the mudskipper and robotic studies were also factored into a mathematical model provided by researchers at Carnegie Mellon University.

The Carnegie Mellon University researchers, who have worked with Goldman on relating the locomotion of other animals to robots, demonstrated that theoretical models developed to describe the complex motion of robots can also be used to understand locomotion in the natural world.

“Our computer modeling tools allow us to visualize, and therefore better understand, how the mudskipper incorporates its tail and flipper motions to locomote,” said Howie Choset, a professor in the Robotics Institute at Carnegie Mellon University. “This work also will advance robotics in those cases where a robot needs to surmount challenging terrains with various inclinations.”

Information from the study could help in the design of robots that may need to move on surfaces such as sand that flows around limbs, said Goldman. Such flow of the substrate can impede motion, depending on the shape of the appendage entering the sand and the type of motion.

But the study’s most significant impact may be to provide new insights into how vertebrates made the transition from water to land.

“We want to ultimately know how natural selection can act to modify structures already present in organisms to allow for locomotion in a fundamentally different environment,” Goldman said. “Swimming and walking on land are fundamentally different, yet these early animals had to make the transition.”

SOURCE  Georgia Tech

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