Ellen Phiddian
Cosmos science journalist
Researchers have figured out exactly how a beetle springs its wings open – and have used the mechanism to make a tiny flying robot.
The Swiss and Korean team has published their findings in Nature.
The rhinoceros beetle (Allomyrina dichotoma), like many flying creatures, can tuck its wings neatly into its body when it’s not flying.
Birds and bats use muscles to do this tucking, but insects have a host of different mechanisms for retracting and deploying their wings.
According to the researchers, beetles have “one of the most complex mechanisms”. This includes hardened forewings, called “elytra”, springing out, followed by delicate hindwings.
The researchers used high-speed camera footage to examine how rhinoceros beetles deploy and retract their wings.
They found the deploying unfolded in 2 phases. First, the elytra are lifted, which releases a spring-like mechanism that allows the hindwings to jump out. Then, the beetles flap the elytra, which allows the tips of the hindwings to unfold “in an origami-like fashion”.
When retracting its wings, the beetles use their elytra to push the hindwings back into position.
This method, contrary to previous suggestions, doesn’t require any muscle movement to shift the hindwings: they’re passive.
The researchers checked this mechanism by building a “microrobot” that passively deployed its wings, like the rhinoceros beetle. They used an elastic tendon to play the role of the beetles’ elytra.
“Over the last decade, numerous flapping-wing robots that mimic insects at various scales have been developed, but they all use flapping wings locked in a fully extended configuration that cannot be retracted after flight, as insects do,” write the researchers in their paper.
The robot could fly stably after deploying its wings, and then retract them neatly at the end of the flight, within 100 milliseconds of the motor stopping.
“We also demonstrated that, if the wings hit an obstacle in flight that caused the robot to destabilize and tumble, they rapidly retracted against the body before reaching the ground, thus helping to prevent wing damage,” write the researchers.
They add that their discovery can help to design more insect-like micromachines.
