For now, RoboFly can only take off and land. Once its photovoltaic cell is out of the direct line of sight of the laser, the robot runs out of power and lands
Scientists, including those of Indian origin, have developed insect-sized flying robots for the first time that are powered by lasers and could help with time-consuming tasks like surveying crop growth on large farms or sniffing out gas leaks. These robots soar by fluttering tiny wings because they are too small to use propellers. They are cheap to produce and can easily slip into tight places that are inaccessible to big drones. Current flying robo-insects are still tethered to the ground. The electronics they need to power and control their wings are too heavy for these miniature robots to carry. RoboFly, developed by researchers from University of Washington (UW) in the US is slightly heavier than a toothpick and is powered by a laser beam. It uses a tiny onboard circuit that converts the laser energy into enough electricity to operate its wings.
“Before now, the concept of wireless insect-sized flying robots was science fiction. Our new wireless RoboFly shows they’re much closer to real life,” said Sawyer Fuller, an assistant professor in the UW. Wing flapping is a power-hungry process, and both the power source and the controller that directs the wings are too big and bulky to ride aboard a tiny robot. Fuller’s previous robo-insect, the RoboBee, had a leash – it received power and control through wires from the ground. However, a flying robot should be able to operate on its own. Researchers decided to use a narrow invisible laser beam to power their robot. They pointed the laser beam at a photovoltaic cell, which is attached above RoboFly and converts the laser light into electricity. “It was the most efficient way to quickly transmit a lot of power to RoboFly without adding much weight,” said Shyam Gollakota, an associate professor at UW. Still, the laser alone does not provide enough voltage to move the wings.
That is why the team designed a circuit that boosted the seven volts coming out of the photovoltaic cell up to the 240 volts needed for flight. To give RoboFly control over its own wings, researchers added a microcontroller to the same circuit. “The microcontroller acts like a real fly’s brain telling wing muscles when to fire,” said Vikram Iyer, a doctoral student in the UW. Specifically, the controller sends voltage in waves to mimic the fluttering of a real insect’s wings. “To make the wings flap forward swiftly, it sends a series of pulses in rapid succession and then slows the pulsing down as you get near the top of the wave. And then it does this in reverse to make the wings flap smoothly in the other direction,” said Johannes James, doctoral student at UW.
For now, RoboFly can only take off and land. Once its photovoltaic cell is out of the direct line of sight of the laser, the robot runs out of power and lands. However, the team hopes to soon be able to steer the laser so that RoboFly can hover and fly around. While RoboFly is currently powered by a laser beam, future versions could use tiny batteries or harvest energy from radio frequency signals, Gollakota said. Future RoboFlies can also look forward to more advanced brains and sensor systems that help the robots navigate and complete tasks on their own, Fuller said.