A robot that dives into the sea, swims underwater and then takes off again like a bird. It is a prototype developed by researchers at MIT and EPFL in Lausanne, Switzerland, inspired by seabirds such as gulls and puffins.
The device, called the FAAV, or "flapping-wing aerial-aquatic vehicle," weighs less than 300 grams. It has a central fuselage, two flexible flapping wings and a motorized steerable tail. Inside is a battery and a waterproof electric motor that drives a crankshaft, moving the wings up and down at preset frequencies. The wings are thin membranes coated with hydrophobic nanoparticles that help shed water. The tail changes angle to make the robot climb or dive.
Tests were carried out in a water tank and on Lake Geneva. The team led by Raphael Zufferey, an assistant professor of mechanical engineering at MIT, identified combinations of wing size, flapping frequency and tail angle that let the robot move smoothly from swimming to flying.
Image: MIT News
The best results came with medium-sized wings, flexible enough to limit flapping amplitude in water and firm enough to keep the robot aloft. Speeds and flapping frequencies are similar to those of real birds. A relatively steep pitch of 70 degrees allows the leap from water into air. Many diving birds paddle their feet to take off, but the robot does not need feet at all.
According to the researchers, the work could pave the way for a new class of drones and vehicles that reach and sample waters too dangerous for traditional boats. "Our dream is for oceanographers, marine biologists and coastal communities to launch this robot from a boat or from shore," says Zufferey. "It would fly close to the area of interest, such as an iceberg or a port, or over a pod of whales, dive to take a measurement or sample, and fly back to deliver the data at a fraction of the cost of traditional methods."
The team is now working on wings that can turn as well as flap, and plans tests in turbulent conditions, such as choppy water or flight in wind. The goal is to use it to answer questions in ocean science. "One of the big challenges in ocean science is collecting data often and across many locations," Zufferey explains. "This robot could do that not just every week, but every hour."
The project fits into EPFL's broader work on biomimetic robotics, such as the RAVEN drone that takes off using legs inspired by crows.
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