Engineers have created a remarkable new robot that can swim underwater and then flap its wings to fly into the air, just like some of nature’s best diving birds.
The invention could one day help scientists study the oceans more safely and at a much lower cost.
The new robot was developed by researchers from the Massachusetts Institute of Technology (MIT) in the United States and the Swiss Federal Institute of Technology Lausanne (EPFL).
Their findings were published in the journal Science.
The robot was inspired by birds such as puffins, loons, gulls and petrels. These birds are skilled both in the air and underwater. They can dive beneath the surface to catch fish and then quickly launch back into the sky.
Scientists wanted to understand how these birds move so easily between two very different environments. Air is light, while water is about 1,000 times denser. Flying and swimming usually require very different body movements and forces.
To explore this mystery, the research team built a lightweight robot weighing less than 300 grams, about the weight of a small apple. The robot has a body, two flexible wings that flap up and down, and a movable tail that helps control its direction. It is powered by a small waterproof electric motor and battery.
The robot’s wings are covered with a special water-repellent coating that helps water slide off quickly after it leaves the surface. The wings can also be replaced with different sizes, allowing the researchers to test which design works best.
The team first tested the robot in a laboratory water tank before moving to Lake Geneva in Switzerland. During each test, they placed the robot about half a meter underwater. They then adjusted the wing size, the speed of the wing flapping and the angle of the tail to see how well the robot could swim upward, break through the surface and continue flying.
After many experiments, the researchers found that medium-sized wings gave the best overall performance. The wings also needed the right balance between flexibility and stiffness. If they were too soft, they could not generate enough lift in the air. If they were too stiff, they did not move efficiently underwater.
The robot swam at nearly one meter per second while flapping its wings about five times every second. Once in the air, it flew at around six meters per second using almost the same flapping speed. These movements closely matched those of real diving birds.
One of the biggest surprises came when the robot left the water. Many birds, including ducks and puffins, use their feet to paddle across the surface before taking off. The researchers expected their robot would need a similar movement.
Instead, they discovered that if the robot pointed upward at an angle of about 70 degrees, its wings alone produced enough force to lift it out of the water. No paddling motion was needed.
The researchers believe this technology could lead to a new generation of aerial-aquatic robots. In the future, these robots could fly over oceans, dive underwater to collect water samples or measure ocean conditions, and then return with the data.
Such robots could also inspect ports, study whales, monitor coral reefs or safely explore dangerous areas such as icy waters near glaciers. Because they can quickly travel through both air and water, they may collect information much more often than traditional research ships.
The team is now improving the robot by designing wings that can also twist during flight, making them even more like real bird wings. They also plan to test how well the robot performs in rough waves and strong winds.
By copying the amazing abilities of diving birds, engineers have taken an important step toward building robots that can explore two worlds—air and water—with a single set of wings.
