A tiny drone powered by soft muscle-like actuators
Kevin Chen
An insect-inspired robot that only weighs as much as a raisin can perform acrobatics and fly for much longer than any previous insect-sized drone without falling apart.
For tiny flying robots to make nimble manoeuvres, they need to be lightweight and agile but also capable of withstanding large forces. Such forces mean that most tiny robots can only fly for around 20 seconds before breaking, which makes it difficult to collect enough data to properly calibrate and test the robots’ flying abilities.
Now, Suhan Kim at the Massachusetts Institute of Technology and his colleagues have developed an insect-like flying robot about the size of a postage stamp that can execute acrobatic manoeuvres, such as double flips or tracing an infinity sign, and also hover in the air for up to 15 minutes without failing.
Kim and his team adapted the design from a previous flying robot, but they made the joints more resilient by having them connect across a larger part of the robot than at just a single failure point. This reduced the force through the joints by a factor of around 100, says Kim. They also used muscle-like soft actuators to move the wings, rather than standard electric motors.
“If you only have 20 seconds to fly the robot before it dies, then there’s not so much we can tune when we control the robot,” says Kim. “By having a hugely increased lifetime, we were able to work on the controller parts so that the robot can achieve precise trajectory tracking, plus aggressive manoeuvres like somersaults.”
This tracking meant that the robot could follow complex flight paths, like tracing letters in the air. Such manoeuvrability could eventually be used for things like artificially pollinating plants or inspecting parts of aircraft that people can’t get to, says Kim.
However, the robot is currently unable to fly untethered, as the team have yet to miniaturise a power source and the electronics that control it – though they hope to improve this with future designs, says Kim.
“One aspect that often doesn’t get talked much about is how long the robot would last when you fly it,” says Raphael Zufferey at the Massachusetts Institute of Technology, who wasn’t involved in the work. “People have focused a lot on battery life and how autonomous we could make it, but no one really focused too much on how long it would mechanically last, and this paper really goes into that in detail.”
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