If you’ve ever knocked a mosquito off your face only to keep it coming back again and again, you know that insects can be remarkably acrobatic and resilient in flight. This helps them to find their way in the air world with all its gusts of wind, obstacles and general uncertainties.
Researchers from Harvard, MIT and the City University of Hong Kong have developed tiny, insect-inspired drones with unprecedented dexterity and resilience. The flying robots are powered by a new class of soft actuators that allow them to maneuver in tight spaces and withstand bumps when something goes wrong.
Most flying drones have to be used outdoors due to their lack of maneuverability, which prevents them from navigating in tight spaces. They also lack the robustness required to survive collisions with other objects. Building small drones requires fundamentally different processes than larger drones. Motors usually power large drones, but these motors lose efficiency when you shrink them to the sizes required for smaller drones.
The new insect-sized drones are based on soft actuators made of thin rubber cylinders coated with carbon nanotubes. When a voltage is applied to the carbon nanotubes, an electrostatic force is generated which compresses and elongates the blanket cylinder. Repeated stretching and contraction causes the drone’s wings to flap nearly 500 times per second, giving the drone an insect-like resilience.
“You can hit it when it flies and it can recover,” said MIT assistant professor Kevin Yufeng Chen. “It can also perform aggressive maneuvers like somersaults in the air.”
The drone weighs just 0.6 grams and looks a bit like a tiny cassette with wings, although Chen is working on a new prototype that is shaped like a dragonfly.
“Achieving a flight with a centimeter-sized robot is always an impressive feat,” says Farrell Helbling, an assistant professor of electrical and computer engineering at Cornell University who was not involved in the research. “Due to the inherent compliance of the soft actuators, the robot can safely encounter obstacles without severely hindering the flight. This feature works well for flight in crowded, dynamic environments and can be very useful for any number of real world applications. “
The next step is to detach the robots from a wired power source, which is currently required by the high operating voltage of the actuators.
Chen hopes that one day the insect-sized drones could help people by performing machine inspections in tight spaces. Other possible uses are artificial pollination of plants or the completion of search and rescue missions after a disaster.