Tuesday, May 24, 2022

Tiny insect-sized drones operate in cramped spaces, withstand collisions

If you’ve ever swatted a mosquito away from your face, only to have it return again and again, you know that insects can be remarkably acrobatic and resilient in flight. This helps them navigate the aerial world, with all of its wind gusts, obstacles, and general uncertainty.

Researchers at 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, allowing them to maneuver in extremely tight spaces and withstand bumps if things go wrong.

Most flying drones have to operate in open spaces due to their lack of agility, which prevents them from navigating tight spaces. They also lack the robustness necessary to survive collisions with other objects. Building small drones requires fundamentally different processes than larger drones. Motors typically power large drones, but those motors lose efficiency as you shrink them to the sizes needed for smaller drones.

The new insect-sized drones rely on soft actuators made of thin rubber cylinders coated in carbon nanotubes. Applying voltage to the carbon nanotubes causes them to produce an electrostatic force that squeezes and elongates the rubber cylinder. Repeated elongation and contraction cause the drone’s wings to beat nearly 500 times per second, giving the drone insect-like resilience.

You can hit it when it’s flying, and it can recover,” MIT Assistant Professor Kevin Yufeng Chen said. “It can also do aggressive maneuvers like somersaults in the air.

The drone weighs only 0.6 grams and looks a bit like a tiny cassette tape with wings, though Chen is working on a new prototype shaped like a dragonfly.

Achieving flight with a centimeter-scale 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. “Because of the soft actuators’ inherent compliance, the robot can safely run into obstacles without greatly inhibiting flight. This feature is well-suited for flight in cluttered, dynamic environments and could be very useful for any number of real-world applications.”

The next step is to untether the robots from a wired power source, which is currently required by the actuators’ high operating voltage.

Chen hopes the insect-sized drones could one day aid humans by performing machinery inspections in cramped spaces. Other potential applications include artificial pollination of crops or completing search-and-rescue missions following a disaster.

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