Engineers at the University of Washington have been working to develop Insect-sized flying robots. These robots could help with time-consuming tasks like surveying crop growth on large farms or sniffing out gas leaks or a number of other applications. They can fly by fluttering tiny wings as they are too small to use propellers, like those used by drones. These robots are cheap to make and can easily slip into tight places that are inaccessible to big drones.
But 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. Now, engineers at the University of Washington have for the first time cut the cord and added a brain, allowing their RoboFly to take its first independent flaps. This might be one small flap for a robot, but its one giant leap for robot-kind. The team will present its findings at the International Conference on Robotics and Automation in Brisbane, Australia.
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. Until now, the concept of wireless insect-sized flying robots was science fiction. The new wireless RoboFly shows they’re much closer to real life.
One of the major engineering challenges in this project has been the flapping of winds to keep the device airborne. 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. The previous robo-insect, the RoboBee, had a leash - it received power and control through wires from the ground. But a flying robot should be able to operate on its own. To do so, the team 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.
This is a very efficient way to quickly transmit a lot of power to RoboFly without adding much weight. Still, the laser alone does not provide enough voltage to move the wings. That’s 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 control over its own wings, the engineers provided a brain: They added a microcontroller to the same circuit. The microcontroller acts like a real fly’s brain telling wing muscles when to fire. 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. To make the wings flap forward swiftly, it sends a series of pulses in rapid succession and then slows the pulsing down as it gets closer to 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 and lands. But the team hopes to soon be able to steer the laser so that it can hover and fly around. While it is currently powered by a laser beam, future versions could use tiny batteries or harvest energy from radio frequency signals. 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.
The research was funded by the University of Washington and a Microsoft student fellowship.
