Birdlike drone able to jump into flight

Inspired by the ability of perching birds to switch frequently between air and land, the so-called RAVEN (Robotic Avian-inspired Vehicle for multiple ENvironments) drone boasts multifunctional robotic legs that allow it to take off autonomously in environments previously inaccessible to winged drones.

It is claimed that technology  - which is described in the journal Nature  - could pave the way for winged drones that can move on rough terrain and take off from restricted locations without human intervention and open up potential applications in inspection, disaster mitigation, and delivery in confined areas.

“Birds were the inspiration for airplanes in the first place, and the Wright brothers made this dream come true, but even today’s planes are still quite far from what birds are capable of,” said EPFL PhD student Won Dong Shin. “Birds can transition from walking to running to the air and back again, without the aid of a runway or launcher. Engineering platforms for these kinds of movements are still missing in robotics.”

Shin designed a set of custom, multifunctional avian legs for a fixed-wing drone and used a combination of mathematical models, computer simulations, and experimental iterations to achieve an optimal balance between leg complexity and overall drone weight (0.62kg). The resulting leg keeps heavier components close to the ‘body’, while a combination of springs and motors mimics powerful avian tendons and muscles. Lightweight avian-inspired feet composed of two articulated structures leverage a passive elastic joint that supports diverse postures for walking, hopping, and jumping.

“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,” said  Dario Floreano from EPFL’s School of Engineering. “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.”

RAVEN’s design allows it to walk, traverse gaps in terrain, and even to 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, and they found that jumping into flight made the most efficient use of kinetic energy (speed) and potential energy (height gain).