The first wireless flying robotic insect takes off

Written by: Bethan Grylls | Published:
Credit: Mark Stone/University of Washington

For the first time, the cord tethering robotic insects to the ground has been cut.

Engineers at the University of Washington (UW) claim to have created the first flying robot, RoboFly, which it said could help with time-consuming tasks like surveying crop growth on large farms or identifying gas leaks.

As the robots are too small to use propellers, like those seen on their larger drone cousins, they work by fluttering tiny wings instead.

But the weight of the electronics required to power and control the winds of these miniature robots have so far proven to be a constraint.

RoboFly 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.

The engineering challenge is the flapping. 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.

Assistant Professor, Sawyer Fuller of UW, has previously worked on flying robotic insects, but Robofly’s predecessor, the RoboBee, had a leash, receiving power and control through wires from the ground.

To lift RoboFly into the air, Prof. Fuller and his team pointed a narrow, invisible 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," explained Associate Professor, Shyam Gollakota of UW.

But, the laser alone does not provide enough voltage to move the wings. To provide the voltage they needed, the team designed a circuit that boosted the seven volts coming out of the photovoltaic cell up to the 240V needed for flight.

And to give RoboFly control over its own wings, the engineers provided a brain: 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 at UW. "On RoboFly, it tells the wings things like 'flap hard now' or 'don't flap.'"

Specifically, the controller sends voltage in waves to mimic the fluttering of a real insect's wings.

"It uses pulses to shape the wave," said Johannes James, the lead author and a mechanical engineering doctoral student, "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."

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. But, the hope is that the team will 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, Assoc Prof. Gollakota said. That way, their power source can be modified for specific tasks.

Future RoboFlies can also look forward to more advanced brains and sensor systems that help the robots navigate and complete tasks on their own, Prof. Fuller added.

"I'd really like to make one that finds methane leaks," he continued. "You could buy a suitcase full of them, open it up, and they would fly around your building looking for plumes of gas coming out of leaky pipes. If these robots can make it easy to find leaks, they will be much more likely to be patched up, which will reduce greenhouse emissions.”

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