Swiss Researchers Develop Revolutionary Bird-Inspired Drone with Robotic Legs

Swiss researchers have unveiled a groundbreaking fixed-wing drone that challenges conventional drone design paradigms by incorporating bird-inspired robotic legs, enabling it to walk, jump, and take off like its biological counterparts. The innovative platform, dubbed RAVEN (Robotic Avian-inspired Vehicle for multiple ENvironments), represents a significant advancement in addressing the limitations of both fixed-wing and rotary-wing unmanned aircraft.

Engineering Breakthrough in Biomimetic Design

The research team at École Polytechnique Fédérale de Lausanne (EPFL) faced a fundamental challenge in drone design: while fixed-wing aircraft offer superior flight efficiency compared to quadcopters, they traditionally require runways or launchers for takeoff. Led by engineer Won Dong Shin, the team developed a novel solution by studying avian biomechanics, particularly focusing on the leg mass ratios of birds like the carrion crow.

The resulting robotic legs weigh approximately 8.1 ounces (230 grams) and feature an innovative two-segment design that eliminates the knee joint while maintaining functionality. A particularly clever element is the incorporation of a torsional spring in the ankle joint, which mimics the energy storage and release mechanism found in bird legs, boosting jumping speed by 25 percent.

Surprising Efficiency Advantages

Perhaps the most unexpected finding of the research was the superior energy efficiency of the jumping takeoff method. While conventional wisdom might suggest that the additional mechanical complexity would result in energy penalties, the data showed otherwise. The jumping takeoff, despite requiring 7.9 percent more energy than a vertical takeoff, proved to be 9.7 times more efficient in terms of energy-to-acceleration ratio.

“I embedded a torsional spring in the ankle joint. When the robot’s leg is crouching, it stores the energy in that spring, and then when the leg stretches out, the spring works together with the motor to generate higher jumping speed,” explained Shin to ARS Technica.

Practical Applications and Future Development

The RAVEN platform demonstrates impressive capabilities. The system can navigate under low ceilings, jump across 4.3-inch (11-centimeter) gaps, and scale obstacles up to 10.2 inches (26 centimeters) in height.

However, significant development work remains before RAVEN can be deployed in real-world applications. Current limitations include:

• The need for pre-programmed movements rather than adaptive navigation
• Inability to use the legs for landing operations
• Lack of sensory feedback for autonomous operation

The research team is already planning improvements, including the integration of vision and haptic sensors, development of foldable wings for enhanced maneuverability in confined spaces, and potential implementation of flapping wing capabilities to further mirror avian landing techniques.

Drone Industry Implications

This development represents a significant step forward in drone technology and could potentially influence future designs across various sectors. The ability to combine efficient fixed-wing flight with ground mobility could prove particularly valuable in scenarios where traditional drones face operational limitations, such as disaster response in complex urban environments or delivery services in mountainous regions.

The success of the RAVEN project also highlights the continuing value of biomimetic approaches in solving complex engineering challenges in the Drohnen-Industrie, suggesting that future developments might increasingly look to nature for innovative solutions to current technological limitations.

Read the original research in Nature.