The RAVEN drone features bird-inspired legs to help improve walking, jumping, take-off, and landing capabilities. (Image Credit: Alain Herzog)
École Polytechnique Fédérale de Lausanne (EPFL) and UC Irvine researchers built RAVEN (Robotic Avian-Inspired Vehicle for multiple ENvironments), a drone that lands and takes flight in places where a fixed-wing aircraft may get stuck. RAVEN is fitted with bird-like legs to assist with walking, avoiding obstacles, and jumping in the air to take flight without a runway.
Typically, quadcopter drones can land and take flight in those areas. However, they use four motors and aren't as energy-efficient as fixed-wing drones equipped with a motor and gliding. The team sought inspiration from the legs of crows and ravens to improve the fixed-wing drones' movement.
To strike the best balance between the drone weight and leg complexity, RAVEN has a combination of mathematical models, computer simulations, and experimental iteration. All the heavy components are integrated close to the body, while the springs and motors act as the avian tendons and muscles. It also has two lightweight bird-inspired feet made of "two articulated structures" with a passive elastic joint, allowing it to position itself to walk, hop, and jump.
"Translating avian legs and feet into a lightweight robotic system presented us with design, integration, and control problems that birds have solved elegantly over the course of evolution," Dario Floreano says. "This led us to not only come up with the most multimodal winged drone to date, but also to shed light on the energetic efficiency of jumping for take-off in both birds and drones."
It's worth noting that RAVEN is designed to "traverse gaps in terrain," walk, and jump 26 cm high. Additionally, the team tested the drone's flight initiation, such as standing, falling, and take-off. They discovered that jumping into flight uses kinetic energy and potential energy more efficiently. Additionally, RAVEN doesn't require human intervention to move on rough terrain and take off from restricted areas. This drone can be used for disaster mitigation, delivery, and inspection in confined locations. RAVEN is already undergoing leg design and control improvements, allowing it to land in various environments.
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