A new kind of robot swims the seas and soars the skies

MIT Engineers Create Dual-Mode Robot Inspired by Seabirds

A new kind of robot swims - Within the mechanical engineering laboratory at the Massachusetts Institute of Technology, researchers have developed an innovative machine capable of navigating both atmospheric and aquatic environments. The facility houses a massive container brimming with vivid blue water alongside numerous ventilation units capable of generating strong gusts. Scattered throughout the space are compact aerial vehicles that capture attention immediately.

These mechanical creations draw their inspiration from ocean-dwelling avians, particularly the Atlantic puffin. This remarkable seabird utilizes its appendages for propulsion across two distinct mediums, demonstrating extraordinary versatility. Raphael Zufferey, a mechanical engineer leading the research team, explained the challenge:

"These puffins solve this really challenging task of moving in air, in water despite the huge difference in density."

Engineering Breakthrough

Zufferey and his fellow scientists sought to construct a machine matching the dimensions of a bird that could traverse both environments and shift between them seamlessly. This achievement represents an unprecedented accomplishment in robotics. Their findings appeared in the prestigious journal Science on Thursday, detailing the development of this remarkable aerial-aquatic device.

The creation weighs approximately half a pound and features a wingspan approaching three feet from tip to tip. Glenna Clifton, an animal movement specialist at the University of Portland in Oregon, praised the design:

"This is a beautiful robot."

Though not directly involved in the project, she collaborates regularly with roboticists and noted that the machine provides valuable insights into the distinctive flight characteristics of diving avians.

Design Innovations

Developing this mechanical marvel required two years of dedicated work. Zufferey remembered his initial skepticism:

"Thinking of a wing that could operate in both [air and water] somewhat efficiently seems implausible."

The team maintained their determination despite these doubts. While adopting a body structure modeled after diving birds, they implemented several crucial modifications. First, they eliminated legs entirely. In robotic applications, legs present considerable challenges regarding construction, control mechanisms, and achieving intended movements.

"Instead, we thought, 'can we go from the water straight to the air simply with the wings themselves?'"

Zufferey explained.

Second, the researchers opted against incorporating foldable wings, which characterize many diving species. Such a design would have introduced unnecessary complexity requiring additional joints and motors.

"So instead we rely on wing flexibility."

The final product displays remarkable elegance. The central housing, containing the motor and power source, remains completely exposed, revealing the internal electronics.

"So water floods the whole system here,"

Zufferey clarified.

"You have to waterproof, individually, every single component."

This methodology enables the machine to remain sufficiently lightweight for aerial navigation while achieving neutral buoyancy, allowing it to remain suspended within the water column.

Performance Capabilities

A tail assists with aerial stability, while the wings utilize translucent nylon fabric strengthened by carbon fiber supports. When Zufferey holds the body, the wings execute rapid, precise movements.

"You can really feel the forces,"

he observed.

During normal flight, the robot oscillates five to six times per second. However, transitioning from water to air requires ten oscillations per second to generate adequate velocity and thrust. Most diving avians cannot produce this level of power through wings alone, necessitating leg-assisted surface running during takeoff. The kingfisher represents an exception due to its particularly light frame.

Video footage captured at Lake Geneva in Switzerland demonstrates the robot's capabilities against a backdrop of distant Alpine peaks. With barely a ripple, the machine emerges from the water and ascends into the atmosphere in under one second, producing sounds reminiscent of avian flight.

Through computational analysis, researchers determined optimal launch angles and wing dimensions. They estimate that a single charge enables approximately four miles of aerial travel or slightly over one mile of underwater navigation.

"Which is longer than the running and swimming portion of a sprint triathlon,"

Clifton noted.

Clifton expressed particular admiration for the achievement:

"It is light and powerful and a monumental step in the performance at both swimming, flying, and transitioning between the two."

Beyond scientific curiosity, this bio-inspired technology holds numerous practical applications. Potential uses include coastal ocean observation and monitoring remote coral reef ecosystems. The robot could navigate to various targets—whether coral formations, whale pods, or algal blooms—collecting valuable environmental data through water sampling.

As Clifton summarized,

"The biology inspires the robotics,"

"but then also the robotics are used to understand the biology."

This reciprocal relationship between natural systems and engineered solutions continues to yield remarkable discoveries in both fields.