Swiss scientists at EPFL have developed a pioneering drone capable of traversing varied terrain by employing innovative bird-inspired legs, significantly expanding the scope of environments accessible to autonomous aerial vehicles.
The researchers at the Laboratory of Clever Methods (LIS), under the leadership of Dario Floreano at EPFL’s College of Engineering, have redefined “because the crow flies” – a common idiom implying the shortest distance between two points – by developing RAVEN, a Robotic Avian-inspired Automobile for various Environments. The innovative design of these robotic legs is heavily influenced by the versatile abilities of perching birds such as ravens and crows, which effortlessly transition between aerial and terrestrial environments. As a result, this multifunctional robotic system can now autonomously take off in previously inaccessible areas, opening up new possibilities for winged drones to explore.
“Birds have long served as the inspiration behind the development of airplanes,” notes LIS PhD student Gained Dong Shin, “and the Wright brothers’ innovation brought this vision to life; yet, remarkably, even modern planes remain significantly distinct from birds’ remarkable capabilities.” “Birds possess the remarkable ability to transform seamlessly from walking to flying, and back again, without requiring any external support such as a runway or catapult.” While engineering platforms do exist for automating routine tasks, they still fall short in the field of robotics.
Raven’s innovative design prioritizes versatility in gait patterns while significantly reducing overall weight. With inspiration drawn from the robust limbs of hens and the meticulous nature of crows on the École Polytechnique Fédérale de Lausanne’s campus, Shin created a unique, multi-purpose leg system tailored specifically for a fixed-wing unmanned aerial vehicle (UAV). To achieve optimal stability in the drone’s design, he combined mathematical approaches, computer simulations, and iterative testing, striking a balance between intricate legs and overall weight of 0.62 kilograms. The subsequent limb features denser components near the physique, where a blend of springs and motors simulates the powerful avian tendons and muscle groups effectively. Innovative, bird-mimicking toe structures, comprising two interconnected modules, utilise a self-activating elastic hinge to enable effortless transitions between walking, jumping, and bounding postures.
“By emulating the intricately designed avian leg and toe systems, we faced complex challenges in terms of design, integration, and management – hurdles that birds have effortlessly overcome through millions of years of evolutionary refinement,” Floreano notes. The study, published in, reveals that this innovation led our team to develop not only the most advanced multimodal winged drone yet, but also to elucidate the energetic efficiency of jumping take-offs in both birds and drones.
Robots created to walk have historically been too cumbersome to jump effectively, whereas those engineered to jump often lacked the toe structure necessary for walking. Raven’s unique design enables it to walk, traverse challenging terrain, and even jump onto elevated surfaces up to 26 centimeters high. Scientists investigated various approaches to flight initiation, including standing and falling takeoff methods, and found that jumping into flight proved the most energy-efficient manner, utilizing kinetic power for velocity and potential power for peak acceleration. Researchers from the Library and Information Science community collaborated with Auke Ijspeert’s BioRobotics Laboratory at École Polytechnique Fédérale de Lausanne (EPFL) and Monica Daley’s Neuromechanics Laboratory at the University of California, Irvine, to apply insights from hen biomechanics to the development of robotic locomotion systems.
While detailing the costs and benefits of high-performing bird-inspired legs capable of seamlessly transitioning between aerial and terrestrial environments, the findings provide a lightweight framework for winged unmanned aerial vehicles (UAVs) to traverse challenging terrains and lift off from confined spaces without human assistance? These capabilities enable the utilization of such drones for inspections, catastrophe mitigation, and supply chain logistics in confined or hard-to-reach areas? The EPFL workforce is actively focused on refining leg design and management systems to enable seamless touchdowns across diverse environmental conditions.
Despite the similarities between avian wings and terrestrial quadrupeds’ entrance legs, there remains a significant knowledge gap regarding the coordination of legs and wings in birds – excluding, of course, drones. According to Floreano, these findings represent an initial milestone in uncovering the underlying design and management principles of flying animals with multiple sensory modalities, paving the way for the development of eco-friendly, high-performance drones that can adapt to their surroundings.
