Raven drone soars with new energy-efficient takeoff method

The bird-robot hybrid has been named by researchers as Raven ("Robotic Avian-inspired Vehicle for multiple Environments", or RAVEN for short). It is a new prototype of a remote-controlled drone that combines a fixed-wing structure and jointed legs, allowing it to navigate various environments and take off more efficiently than current drones. Scientists showcased their discovery in the scientific journal "Nature".

Its design, in terms of dimensions and weight, resembles a real raven - the robot-raven is approximately 50 centimetres long, has a wingspan of 1 metre, and weighs about 0.6 kilograms - providing an optimal combination of strength and weight. It can walk, jump over gaps and obstacles, and take off from standing, falling, and jumping positions. The invention uses bird-like legs for walking, jumping, and quick takeoff to flight, which, according to scientists, is more energy-efficient compared to takeoff using only propeller-driven propulsion.

In the published article in "Nature", researchers compare the efficiency of different takeoff strategies, showing the advantage of jumping. Studies revealed that takeoffs using jumps are ten times more energy-efficient than traditional ones and allow higher takeoff speeds, reaching up to 2.4 metres per second. It was observed that the legs alone generate a speed of 2.1 metres per second, which constitutes as much as 91.7% of the target takeoff speed, highlighting the effectiveness of the limb design compared to propellers.

According to researchers' calculations, the bird drone's jump takeoff generated a higher takeoff speed, acceleration, output power, and energy efficiency than standing and falling takeoffs. Compared with other multifunctional drones, it shows that adding more modes of locomotion reduces the efficiency of similar drones. The robot-raven can take off from higher places, similar to birds that jump to take flight. During the flight, the device is propelled by a single propeller located at the front, and the direction of its flight is controlled by the tail at the back.

Research published in "Nature" proves that the RAVEN design opens new possibilities for drones in more challenging terrain. This innovative mechanism combines features of fixed-wing elements and jointed legs, allowing it to operate in diverse environments and take off more efficiently than standard drones.

The robot also uses flexible legs for surface movement and adaptation to difficult terrains. As the robot-raven moves, it maintains a vertical posture thanks to advanced limb features, such as bends in the hips and ankles, which maximize kinetic energy during jumps, and flexible finger joints that allow the feet to be set at various angles without the risk of tipping over.

Although standard unmanned aerial vehicles are more durable, they require a large takeoff space – similar to airplanes, according to the study. Some drones are launched into the air using a catapult, similar to those on aircraft carriers, but they are less flexible regarding applications. The new raven-drone prototype - according to scientists - with its faster takeoff could revolutionize the takeoff mechanism for drones once and for all.

The scientists hope their invention will become a model for larger drones and perhaps even for standard-sized airplanes. These improvements could significantly enhance stability during landings and the overall potential of flying machines, as researchers speculate.