The latest bio-inspired robot is helping researchers to understand how baby sea turtles make their way across sand toward the ocean. It's often a treacherous journey for the animals, so researchers are hoping FlipperBot will allow them to understand the mechanics behind the movements as well as how and why animals evolved flippers in the first place.
Phys.org says, "The research could help robot designers better understand locomotion on complex surfaces and lead biologists to a clearer picture of how sea turtles and other animals like mudskippers use their flippers. The research could also help explain how animals evolved limbs – including flippers – for walking on land."
"We are looking at different ways that robots can move about on sand," said Daniel Goldman, an associate professor in the School of Physics at the Georgia Institute of Technology. "We wanted to make a systematic study of what makes flippers useful or effective. We've learned that the flow of the materials plays a large role in the strategy that can be used by either animals or robots."
In order to create the FlipperBot, Nicole Mazouchova, then a graduate student in the Georgia Tech School of Biology, studied the baby turtles using a trackway filled with beach sand near the beach. As the turtles moved across the sand toward an LED light used to mimic the moon, she recorded kinematic and biomechanical data. She found that all 25 hatchlings were able to move efficiently across both soft and hard sand, maintaining their speed the whole time.
The researcher believe that the animals are able to control their wrists and change how they use their flippers depending on the surface. On soft sand, this means allowing the wrists to bend so that the sand doesn't flow around the flippers and cause them to slip. On hard sand, they keep their wrists locked to better propel them forward.
The FlipperBot measures about 19 centimeters in length, weighs about 970 grams, and has two flippers driven by servo-motors. Like the turtles, the robot has flexible wrists that allow variations in its movement. The researcher have tested its movements by placing it in a track full of poppy seeds. They've found that the flexible wrists keeps the robot from getting stuck in the shifting material, but that it runs into trouble when it hits material that has already been disturbed, something that posed a problem for the sea turtle hatchlings as well.
The research could help develop new amphibious robots that use flippers for moving over sand and also through water and could ultimately provide clues to how turtles evolved to walk on land with appendages designed for swimming.
"To understand the mechanics of how the first terrestrial animals moved, you have to understand how their flipper-like limbs interacted with complex, yielding substrates like mud flats," said Goldman. "We don't have solid results on the evolutionary questions yet, but this certainly points to a way that we could address these issues."