Bio-inspired airborne robot makes soft water landing, converts to autonomous sailboat

Mother Nature spent millions of years perfecting the maple seed’s gentle spiral to the forest floor and the fish’s swift flick through open water. She never thought to combine them.

Robotic experts at Singapore University of Technology and Design and MIT just did. Introducing ALBATROSS, a hybrid robot that leaps out of the sky like a spinning seed, splashes into the water, and instantly morphs into an autonomous, wind-driven sailboat.

Short for Airborne Lander with Buoyant AuToROtating Sailing Sensor, the device offers a low-cost solution to a difficult engineering problem: building a machine that operates in both air and sea without collapsing under its own weight.

“In repeated field trials at two reservoirs in Singapore, the robot sailed autonomously using a Rule-Based (RB) controller after being deployed from 150 meters in the air,” the team noted.

Drop, splash, sail

Typically, dual-environment drones are heavy, complex, and ruinously expensive. And require bulky motors to fight gravity in the air and separate propulsion systems to navigate currents below. ALBATROSS could change that.

Instead of fighting physics, it borrows from nature’s cleverest hacks. During a 150-meter drop from the sky, its two rigid wingsails spin passively like a falling maple seed. It achieves a soft, controlled, spinning descent without relying on heavy engines or draining battery power.

The moment it hits the surface, the transformation begins.

Those same aerial wings lock into place as wind-driven sails, turning the fallen lander into an agile aquatic scout. Beneath the waterline, a tail rudder modeled after a fish fin takes over. When the breeze dies, the fin flicks to push the craft forward; when the wind picks up, it guides the vessel upwind toward its target.

The ~1-kg ALBATROSS robot autorotates during air descent to cut its fall speed to ~7 m/s, reducing impact energy 18-fold so it survives impact with the water. Upon landing, the craft passively self-rights and transitions its dual wingsails to wind propulsion without active morphing, achieving a high 91 percent effective mass usage across air and water.

In low-wind conditions, the platform drives itself forward up to 0.4 m/s through an oscillating fish-tail rudder. The design proves how recombining distinct bio-inspired components can expand operating envelopes without adding extra weight.

Borrowing from nature

By reusing its body parts for dual roles, the design team stripped the robot down to just three actuators and three primary sensors. It is lightweight, lean, and deceptively simple.

In field tests across two Singaporean reservoirs, ALBATROSS proved it could survive high-altitude drops and immediately start sailing autonomously using a rule-based navigation controller. Computer simulations show that with Reinforcement Learning algorithms, the craft can even master complex waypoint missions entirely on its own.

The development highlights a fresh approach to bio-inspired robotics. In an accompanying commentary, researchers suggest that nature serves best as a versatile library of individual biological mechanisms rather than an exact blueprint.

Multimodal robotics combines diverse locomotion modes into a single platform to navigate across different environments. While animals excel at repurposing biological structures for multiple habitats, nature should serve as a flexible parts library rather than a strict blueprint.

Robotics engineers can select, adapt, and recombine individual biological mechanisms to address specific technical challenges that evolutionary pressures never encountered.

With climate monitoring and disaster response demanding faster, cheaper eyes on the water, ALBATROSS shows that sometimes the best way to conquer two worlds is to simply drop in and let the wind do the work.

Source: https://interestingengineering.com/ai-robotics/bio-inspired-airborne-robot-soft-landing