Insect-Inspired RoboBee X-Wing Uses Solar Power To Fly

Researchers have long envisioned deploying armies of tiny flying robots to tackle vital tasks. The versatile machines could be used as first responders to trace gas or pollutant seepage during natural disasters, to survey crops in large farms, to help astronauts on space missions, and even to assist bees with plant pollination. However, fitting the heavy electronics required to power and control the wings into the robot's tiny frame has been challenging. Now, there is hope, thanks to RoboBee X-Wing — the world's lightest aerial vehicle that can fly without being tethered to a power source.

Unveiled by Harvard researchers on June 26, 2019, the insect-inspired robot weighs a mere 259 milligrams, has a wingspan of 3.5 centimeters, and stands 6.5 centimeters high. Its four tiny wings, which can flap up to 170 times a second, are controlled by actuators — muscle-like plates — that contract when the voltage passes through them. Six small solar cells, fitted above the wings to prevent them from interfering with the flight, provide the power.

To test its flying capabilities, the team, led by postdoctoral fellow Noah Jafferis and PhD student Elizabeth Helbling, exposed the RoboBee X-Wing's solar cells to a combination of halogen and LED lighting. To their delight, the tiny robot's wings began to flap, and it rose, sustaining an untethered flight for about half a second. Though the robot, which was tied to a Kevlar safety harness, lost its flight capability as soon as the power source was switched off, its short, unassisted flight was hailed as a huge milestone for the future of tiny flying robots.

However, though the current prototype is a step in the right direction, RoboBee X-Wing is not quite ready for prime time. The diminutive robot has no navigation capabilities and, more importantly, requires light three times brighter than the sun to operate, which means it would not be able to lift off outside the laboratory. Additionally, RoboBee X-Wing is not equipped to withstand even a slight breeze, let alone the wind gusts it is likely to encounter as it goes about performing important tasks. But Jafferis and Helbling, who published their research in the journal Nature, are not fazed by the challenges. The team is already working on a new and improved version of the robot — one that is 25 percent bigger and needs light just 1.5 times brighter than the sun to work.

The Harvard researchers are not the only scientists trying to create untethered flying robots. RoboFly, unveiled by University of Washington (UW) engineers in May 2018, draws its power from an invisible laser beam. Similar to the RoboBee X-Wing, the tiny machine, which weighs just 190 milligrams, needs to be in the direct line of sight to its power source to stay aloft. Though the robot can currently only take off and land, the team, led by Sawyer Fuller, an assistant professor at UW's Department of Mechanical Engineering, is working on ways to steer the laser to allow RoboFly to hover and fly around. The researchers also hope to experiment with other power sources, such as tiny batteries or energy harvested from radio frequency signals, and to add more advanced "brains" and sensor systems that will enable future versions of the aerial machine to navigate and accomplish tasks independently.

Resources: newscientist.com,sciencedaily.com,wired.com, nature.com