Although wing-flapping micro-drones do already exist, the things tend to be quite fragile – and thus not ideally suited to real-world use. An experimental new one, however, utilizes a softer mechanism for greatly enhanced durability.
Currently, most insect-inspired MAVs (micro aerial vehicles) utilize a tiny rigid actuator to rapidly move their wings. Made of piezoelectric ceramic materials, these actuators are brittle and unyielding, so they're easily damaged in crashes. Given how often MAVs are tossed around by wind gusts and whatnot, such crashes are bound to occur frequently.
Seeking a more robust alternative, scientists from MIT, Harvard University and City University of Hong Kong developed a drone with soft actuators. Each actuator takes the form of a thin rubber cylinder coated in carbon nanotubes.
When voltage is applied to the device, the nanotubes produce an electrostatic force which both squeezes and elongates the cylinder. Once that voltage is shut off, the cylinder contracts back to its default state. Therefore, by rapidly switching the electrical current on and off, the actuator in turn expands and contracts, flapping the attached wings almost 500 times per second as it does so.
As a result, not only can the drone fly, but it's also relatively tough.
"You can hit it when it’s flying, and it can recover," says the lead scientist, MIT's Asst. Prof. Kevin Yufeng Chen. "It can also do aggressive maneuvers like somersaults in the air."
The current prototype consists of four sets of the wings and actuators, joined together on one rectangular frame. It tips the scales at 0.6 grams, which is about the weight of a bumblebee. That said, it is hard-wired to an external power source. The scientists hope that by lowering its power requirements, it will eventually be able to get by with a small onboard battery.
Ultimately, descendants of the current drone may find use in applications such as pollinating crops, or performing search-and-rescue missions within confined spaces such as the rubble of collapsed buildings.
You can see the MAV in action, in the video below. The technology is described in a paper that was recently published in the journal IEEE Transactions on Robotics.
Source: MIT