Engineers at Harvard University have created a millionth-scale automobile differential to govern the flight of minuscule aerial robots that could someday be used to probe environmental hazards, forest fires, and other places too perilous for people.. The device is literally one one-millionth the size of what you’d find in your car.
Their new approach is the first to passively balance the aerodynamic forces encountered by these miniature flying devices, letting their wings flap asymmetrically in response to gusts of wind, wing damage, and other real-world impediments.
“The drivetrain for an aerial microrobot shares many characteristics with a two-wheel-drive automobile,” said Pratheev S. Sreetharan, a graduate student in Harvard’s School of Engineering and Applied Sciences. “Both deliver power from a single source to a pair of wheels or wings. But our PARITy differential generates torques up to 10 million times smaller than in a car, is 5 millimeters long, and weighs about one-hundredth of a gram.” PARITy is an acronym for Passive Aeromechanical Regulation of Imbalanced Torques.