Researchers at École Polytechnique Fédérale de Lausanne (EPFL), Switzerland, have proved to the world that they have made the greatest step forward in robotics and drone technology by designing RAVEN: Robotic Avian-inspired Vehicle for Multiple Environments, a lightweight bird-inspired drone which includes mechanical legs. These mechanical legs provide the drone with the ability to walk, hop, and jump high-all capabilities that might change the mode of operation of drones on complicated terrains as well as during takeoffs.
RAVEN mimics avian biology, for example, crow leg movements-the jumping and flying initiation juncture in conjunction with the ground-on almost all birds. Engineered for energy-efficient jumps, the mechanical legs enable the drone to launch itself directly off the ground, without the use of runways or catapults, something typical fixed-wing drones fail to do. This will likely transform how drones are used as they now will be able to multiply their options in navigation under difficult environments while retaining fixed-wing-endurance and ranges.
A Bird’s-Eye View of the Design
Won Dong Shin, a doctoral student at EPFL’s Laboratory of Intelligent Systems, laid the groundwork for RAVEN. He was influenced by the agility of birds, mostly crows around the EPFL campus, which brought butterflies to observe them jumping to initiate flights even when given the option of flying. This served as the basis for the discovery into what would happen if this type of action were brought into the design for drones, this time concerning the biomechanics for a birdlike leg motion.
“I saw how crows were walking, how they jumped over obstacles, and how they were taking off with jumping,” Shin explained. “What struck me was their ability to initiate take-off by jumping even where they could have just flown.” The final design is RAVEN-a fixed-wing drone the size of a crow, with a wingspan measuring about 100 centimeters, and a body length of 50 cm. It is equipped with mechanical legs that walk a meter in just under four seconds, and can hop across gaps stretching as wide as 12 cm, as well as jump over obstacles upward of 26 cm in height. It can leap into the air with an initial jump really close to half a meter in altitude, propelling itself at a speed of 2.2 m/s forward.
Bio-Inspired Mechanics The most clever part in the design of RAVEN is its toe mechanism. Most bipedal robots use actuated feet for controlling foot placement, but the addition of actuators increases all the weight and complexities in the system. Instead, RAVEN employs passive elastic toe joints that store and release energy in a tendon-like manner, much like in the muscles and tendons of a bird’s legs. This added feature helps the drone have effective jumps but keeps the overall weight to a minimum. RAVEN accounts for just 620 grams, where 230 grams out of that is accounted for its legs, feet, and actuators. It is the combination of a lightweight design and birdlike mechanics that have powered RAVEN so efficiently both on the floor and up in the air. Jumping vs. Traditional Takeoffs The addition of jumping legs raises a very good question: Is the cost in weight and complexity worth it for the gains in performance? Research says “yes”. While the mechanical legs add weight, they allow RAVEN to take off from the ground without having to use traditional methods such as propellers or catapults. The tests showed that jumping for takeoff is more efficient and faster than standing takeoffs, which can lead to unstable flight due to high angle-of-attack and low takeoff speed.
“No doubt, the energized take-off, which relies on jumping, is almost ten times more effective in energy use than the static take-off,” Shin stated, adding that “it is the most energy lean and the fastest way of converting actuating energy into kinetic and potential energy.”
It enables RAVEN to deal with suboptimal surfaces-it makes RAVEN more adaptable to taking off and landing in areas where most conventional unmanned aerial vehicles would encounter considerable difficulty.
Scaling up and Future Potential
The attitude of RAVEN is small and agile. But will this jumping, bird-like concept become reality in larger drones which can then carry meaningful payloads? Shin was hopeful but aware of the challenges. Compromises must be made because the larger payload may not benefit from the jumping take-off. But Shin is optimistic. He says it is easier to scale engineered systems than biological ones.
He also sees future modifications to the RAVEN design such as integrating flapping wings into the system for an even more bird-like type of motion. Such flapping wings would add to versatility to the drone because it could do more complex maneuvers and go to even more diverse environments.
“Birds use their legs for a lot of activities other than walking and jumping,” Shin continues. “We want to extend ranges of operations of RAVEN-for instance, landing using legs for deceleration, and eventually even these forms for swimming, perching, and snatching objects.”
What Next
The possibilities for application for a drone like RAVEN are limitless. From agricultural surveying to search-and-rescue missions, its capability for flying through difficult terrain, taking off and landing from almost any venue, and flight efficiency, is sure to bring exciting new advances in the science of drone technology.
Continuous improvement of the design and features will ensure that RAVEN is soon going to be a major contender in sectors that rely on drone technology for surveillance, delivery, or other specialty tasks. Bird-inspired leg movement will be introduced into the drone design, marking a new frontier for the robotics field, with RAVEN being the very beginning of what is surely going to be a revolution in aerial mobility.
Written by Mr. Benjamin Joseph from Federal University of Technology Yola and Eddited by Mr. Chibueze Onwuka Uko.