Sub-gram Helicopters

While much of the eVTOL and UAV communities are focused on automobile-sized transportation vehicles to move people, products, and cargo relatively short distances (e.g. from an airport to a city center), a group of scientists are looking in the opposite direction: designing tiny helicopters – less than 10 millimeters in size – to go where the rest of the fleets can’t. Keep in mind the largest gnat measures a mere 13 millimeters; these UAVs will be nearly 30% smaller.

With funding from the U.S.’s National Science Foundation, a team of undergraduate, graduate, and postgraduate students, and their professors at the University of Washington produced a paper which designs and demonstrates the possibility of manufacturing a sub-gram helicopter using sub-gram motors and, uniquely, a “light-weight, microfabricated flybar mechanism to passively stabilize” their flying robot.

It’s a Small eVTOL World After All

Ever been to any of the Disney theme parks? Then, you’ve heard the “small world” song refrain over and over again (perhaps ad nauseum). Leveraging the high lift, reliability, and low-voltage of sub-gram motors, the team has taken to its tiny task and fashioned a foldable 48 milligram flybar that becomes a tiltable flybar to modulate the angle of attack of the rotors.

The scientists have been able to achieve a peak damping ratio of 0.528 that achieves a stable roll and pitch with relative deviations <1°. When combined with a counter-torque mechanism, e.g., a tail rotor, this mini flybar provides the attitude stability necessary for a sub-gram helicopter.

Show Us the Big Bucks from This Tiny Machine

The scientists foresee sub-gram aerial robots transforming search and rescue missions, gas leak detection, wireless networking, 3-D mapping and environmental monitoring. A swarm of sub-gram helicopters equipped with various sensors would enjoy extended airtime or perhaps even battery-free operations. With its lift force of 2.8 grams, and an ~200 milligram avionics system.

The use of a foldable flybar enables high thrust of small motors, yet minimizes size, weight, and power. The researchers claim a single flybar stabilized rotor could create a controlled helicopter at a scale of 2-3 centimeters.

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