Nature has given us amphibians in a variety of forms, from frogs to other multi-environment creatures, yet few things transcend Earth’s different domains, like the diving birds that inspired MIT and EPFL researchers. For a long time, scientists have been dreaming of a machine that could fly through the clouds like birds, swim in the depths of the ocean and then return to the sky seamlessly. Diving birds, such as the ‘Atlantic puffin’, glide effortlessly between air and sea, despite the different physical properties of the two environments. Now a team of engineers from MIT and the Swiss Federal Institute of Technology (EPFL) has finally created a lightweight, winged robot that has this biological ability, showing that a single wing can navigate both worlds. This success is a major step forward in exploring and monitoring our vast, mysterious oceans.
Why is this MIT robot so special?
To understand the significance of this achievement, we first have to look at science. Water is about 1,000 times denser than air. Typically, a wing designed to lift a robot into the air would be too fragile or incapable of overcoming the heavy resistance of water. Most previous attempts at ‘amphibious’ drones had two separate systems of propellers and wings working together, making them heavy and complex.The MIT team led by Raphael Zafari took a different approach by looking at puffins. Their creation, known as the ‘Flapping-Wing Aerial-Aquatic Vehicle (FAAV)’, weighs less than 300 grams, which is equivalent to a large apple. It does not use a propeller or additional engine; Instead, it relies entirely on a pair of wings for both flying and swimming. By studying nearly 100 species of diving birds, researchers created a machine that smoothly handles the transition between air and water.
How this amphibious robot handles air and water together
Its secret lies in the flexibility of the wings. Instead of using mechanical joints to fold its wings underwater like a real bird, the robot uses ‘flexible membrane wings’ reinforced with carbon fiber struts. When the robot is in the air, these wings are strong enough to lift the robot for flight. However, as soon as it hits the water, the wings passively flex 90 degrees. This quick change reduces the surface area of the fin, which reduces the load on the motor, allowing it to move through the water without breaking.Another clever design choice was the ‘open-body frame’. Instead of trying to create a heavy, airtight casing to protect the electronics, engineers allowed the entire system to flood. Each individual component such as the motor, battery and sensor is separately waterproofed with silicone. This allows the robot to remain exactly where it is in the water without sinking or floating on the surface. This saves the huge amount of battery power previously required to avoid floating.
Image Credit: John Friedah
Can this robot really fly without run-up?
One of the most impressive parts of the MIT study was ‘drainage’. If you’ve ever watched a duck or puffin fly from a lake, you may have seen them rapidly paddling their legs to get enough speed to fly. The researchers initially thought their robot would need something similar.However, he discovered a mechanical shortcut. By programming the robot to pitch upward at an acute 70-degree angle, the wings alone can generate enough thrust to pull it out of the water and into the air in less than a second. To achieve this, the robot has to flap about 10 times a second to break free from the surface tension of the water. This is a power-consuming step, but it eliminates the need for heavy robotic legs, keeping the machine lightweight.
What has this robot taught us about our nature?
This project is a tool for biological discovery. Scientists have long debated why diving birds reduce the area of their wings underwater. Is it to save energy, or to gain speed? By testing different wing sizes and flexibilities on their robot, the team found that smaller wings don’t actually save energy. Instead, they significantly increase speed and navigation underwater. This shows that when a puffin flaps its wings, it is not trying to be efficient, but rather fast. The robot also confirmed that large diving birds would likely have to use their legs to fly because only wing launch requires energy. Only the smallest, lightest birds, such as kingfishers, can afford to abandon foot-based takeoff, which matches exactly what the researchers observed in their bird-scale robot.
What does this mean for the future of marine research?
The potential applications for FAAVs are vast. Traditional marine research often requires large, expensive ships or slow-moving underwater robots. Zafari’s vision is to provide a much cheaper and faster option. Imagine a group of these ‘aero-aquatic robots’ that could fly at speeds of six meters per second to a specific area of interest, such as a remote coral reef, or a pod of whales. They can dive, take water samples or temperature readings, and then fly back to base to deliver data. On a single charge, the current prototype can fly about four miles or swim for a little more than a mile. The best part is that the researchers have made their design open-source. With about £230 ($300) of materials and a 3D printer, coastal communities and marine biologists can create their own fleet of aerial-aquatic robots.By mimicking the amazing abilities of diving birds, we are finally creating technology that can navigate our planet as easily as animals, ushering in a new era of oceanography that is faster, cheaper and far more detailed than ever before.