Watching how grasshoppers glide inspires new flying robot design
While much insight has been gleaned from how grasshoppers hop, their gliding prowess has mostly been overlooked. Now researchers at Princeton University have studied how these gangly insects deploy and retract their wings to inspire a new approach to flying robots.
Typical insect-inspired robot designs are often based on bees and flies. They feature constant flapping motion, yet that requires a lot of power so the robots either carry heavy batteries or are tethered to a power supply.
Grasshoppers, however, are able to jump and glide as well as flap their wings and while they are not the best gliding insect, they have another trick as they are able to retract and unfurl their wings.
Grasshoppers have two sets of wings, the forewings and hindwings. The front wing is mainly used for protection and camouflage while the hindwing is used for flight. The hindwing is corrugated, which allows it to fold in neatly like an accordion.
A team of engineers, biologists and entomologists, analysed the wings of the American grasshopper, also known as the bird grasshopper, due to its superior flying skills. They took CT scans of the insects and then used the findings to 3D-print model wings. They then attached the wings to small frames to create grasshopper-inspired gliders finding that their performance was on par with that of actual grasshoppers.
They also tweaked certain wing features such as the shape, camber and corrugation, finding that a smooth wing actually produced gliding that was more efficient and repeatable than one with corrugations. “This showed us that these corrugations might have evolved for other reasons,” notes Princeton engineer Aimy Wissa, who adds that “very little” is known about how grasshoppers deploy their wings.
The researchers say that further work could result in new ways to extend the flight time for insect-sized robots without the need for heavy batteries of tethering. “This grasshopper research opens up new possibilities not only for flight, but also for multimodal locomotion,” adds Lee. “By combining biology with engineering, we’re able to build and ideate on something completely new.”
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