Tokyo (SCCIJ) – Drones are becoming versatile tools for civilian and military purposes. Now, researchers in Switzerland have built a unique drone that can walk, hop, and jump into flight with birdlike legs. This addition greatly expands the range of environments accessible to crewless aerial vehicles.
Birds as role models
The Laboratory of Intelligent Systems at the School of Engineering of the Swiss Federal Institute of Technology in Lausanne (EPFL) developed the multifunctional robotic legs. The engineers christened the drones RAVEN, an abbreviation for Robotic Avian-inspired Vehicle for Multiple Environments. Perching birds like ravens and crows frequently switching between air and land were role models.
“Birds can transition from walking to running to the air and back again, without a runway or launcher. Engineering platforms for these movements are still missing in robotics,” says PhD student Won Dong Shin at the Laboratory of Intelligent Systems.
RAVEN’s design maximizes gait diversity while minimizing mass. Inspired by the proportions of bird legs, Shin used mathematical models, computer simulations, and experimental iterations to achieve an optimal balance between leg complexity and an overall drone weight of only 620 grams. A combination of springs and motors mimics powerful avian tendons and muscles. A passive elastic joint supports diverse postures for walking, hopping, and jumping.
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Deliveries and disaster relief
Previous robots designed to walk were too heavy to jump, and robots designed to jump did not have feet suitable for walking. RAVEN’s unique design allows it to walk, traverse gaps in terrain, and even jump up onto an elevated surface 26 centimeters high. The scientists also experimented with different modes of flight initiation, including standing and falling take-off. They found that jumping into flight made the most efficient use of kinetic energy (speed) and potential energy (height gain).
In addition to elucidating the costs and benefits of powerful legs in birds that frequently transition between air and ground, the results offer a lightweight design for winged drones that can move on rough terrain and take off from restricted locations without human intervention. These capabilities enable the use of such drones in inspection, disaster mitigation, and delivery in confined areas. The EPFL team is already working on improved design and control of the legs to facilitate landing in various environments.
Text: Celia Luterbacher/EPFL News (Editing by SCCIJ)
