Over 100 bird species, including loons, gulls, puffins, and petrels, can both fly and swim. Inspired by these diving birds, engineers from MIT and EPFL have developed a robot that swims underwater and then flaps out of the water to continue flying, known as the Flapping-Wing Aerial-Aquatic Vehicle (FAAV).
Weighing under 300 grams, this robot is designed to help scientists study the mechanics that allow diving birds to navigate both air and water. The robot features a central body, two flexible flapping wings, and a steerable tail, with interchangeable wing and tail sizes. Experiments in a water tank and at a local lake identified the optimal combinations of wing size, flapping frequency, and tail angle for smooth transitions between swimming and flying.
Their findings, published in Science, could enhance our understanding of how diving birds adapt their flight mechanics to traverse different physical environments. The researchers envision deploying these winged robots in oceanography to access hazardous aquatic regions that traditional vessels cannot reach.
“Our dream is for oceanographers and marine biologists to launch this robot from a boat or shore, allowing it to fly near areas of interest, dive for measurements or samples, and return with data at a fraction of traditional costs,” says Raphael Zufferey, an assistant professor at MIT.
At MIT's AURA Lab, Zufferey leads a team focused on creating small aerial and aquatic vehicles inspired by nature's biomechanics. Their goal was to design a vehicle capable of transitioning between air and water, overcoming the significant density differences.
By reviewing scientific literature on diving birds, the team learned that smaller birds flap their wings about 10 times per second in air and four times per second in water. Using this knowledge, they developed a robot with wing flapping frequencies mimicking those of diving birds.
The new robot resembles a bird, containing a battery and a waterproof electric motor that drives a crankshaft to flap the wings. The wings are made from thin membranes coated with hydrophobic nanoparticles, and the tail is motorized to adjust its angle for flight. They tested three sets of wings: small (60 cm), medium (80 cm), and large (100 cm).
In experiments, the robot was submerged about half a meter underwater, programmed to flap its wings at specific frequencies while adjusting its tail angle. The team found that the robot could reliably swim, fly, and transition between water and air using medium-sized wings.
The robot swam at nearly 1 meter per second and flew at around 6 meters per second. To leap from water to air, it needed to be pitched at a steep angle of 70 degrees, avoiding water surface contact. Interestingly, the robot achieved this without the paddling motion that many diving birds require.
Moving forward, the team plans to enhance wing design for turning capabilities and test the robot's performance in turbulent conditions. Zufferey states, “One of the major challenges in ocean science is frequent data collection across various locations, and this robot could address that in the future.”
Blogger's Review: This innovative aerial-aquatic robot showcases a remarkable advancement in technology and offers new perspectives for ocean science research. Its design, inspired by nature, exemplifies the immense potential of biomimetic engineering. The future applications, especially in data collection efficiency, are promising, as the robot could thrive in extreme environments.