Hummingbirds occupy a singular place in nature: They fly like bugs however have the musculoskeletal system of birds. In keeping with Bo Cheng, the Kenneth Okay. and Olivia J. Kuo Early Profession Affiliate Professor in Mechanical Engineering at Penn State, hummingbirds have excessive aerial agility and flight varieties, which is why many drones and different aerial autos are designed to imitate hummingbird motion. Utilizing a novel modeling technique, Cheng and his crew of researchers gained new insights into how hummingbirds produce wing motion, which might result in design enhancements in flying robots.
Their outcomes had been printed this week within the Proceedings of Royal Society B.
“We primarily reverse-engineered the internal working of the wing musculoskeletal system — how the muscle tissues and skeleton work in hummingbirds to flap the wings,” mentioned first writer and Penn State mechanical engineering graduate pupil Suyash Agrawal. “The standard strategies have largely targeted on measuring exercise of a hen or insect when they’re in pure flight or in a synthetic atmosphere the place flight-like circumstances are simulated. However most bugs and, amongst birds particularly, hummingbirds are very small. The info that we will get from these measurements are restricted.”
The researchers used muscle anatomy literature, computational fluid dynamics simulation information and wing-skeletal motion info captured utilizing micro-CT and X-ray strategies to tell their mannequin. In addition they used an optimization algorithm primarily based on evolutionary methods, often known as the genetic algorithm, to calibrate the parameters of the mannequin. In keeping with the researchers, their method is the primary to combine these disparate components for organic fliers.
“We are able to simulate the entire reconstructed movement of the hummingbird wing after which simulate all of the flows and forces generated by the flapping wing, together with all of the stress appearing on the wing,” Cheng mentioned. “From that, we’re in a position to back-calculate the required whole muscular torque that’s wanted to flap the wing. And that torque is one thing we use to calibrate our mannequin.”
With this mannequin, the researchers uncovered beforehand unknown rules of hummingbird wing actuation.
The primary discovery, in response to Cheng, was that hummingbirds’ major muscle tissues, that’s, their flight engines, don’t merely flap their wings in a easy forwards and backwards movement, however as an alternative pull their wings in three instructions: up and down, forwards and backwards, and twisting — or pitching — of the wing. The researchers additionally discovered that hummingbirds tighten their shoulder joints in each the up-and-down course and the pitch course utilizing a number of smaller muscle tissues.
“It is like once we do health coaching and a coach says to tighten your core to be extra agile,” Cheng mentioned. “We discovered that hummingbirds are utilizing comparable sort of a mechanism. They tighten their wings within the pitch and up-down instructions however hold the wing free alongside the back-and-forth course, so their wings look like flapping forwards and backwards solely whereas their energy muscle tissues, or their flight engines, are literally pulling the wings in all three instructions. On this method, the wings have superb agility within the up and down movement in addition to the twist movement.”
Whereas Cheng emphasised that the outcomes from the optimized mannequin are predictions that may want validation, he mentioned that it has implications for technological growth of aerial autos.
“Although the know-how will not be there but to completely mimic hummingbird flight, our work gives important rules for knowledgeable mimicry of hummingbirds hopefully for the following era of agile aerial techniques,” he mentioned.
The opposite authors had been Zafar Anwar, a doctoral pupil within the Penn State Division of Mechanical Engineering; Bret W. Tobalske of the Division of Organic Sciences on the College of Montana; Haoxiang Luo of the Division of Mechanical Engineering at Vanderbilt College; and Tyson L. Hedrick of the Division of Biology on the College of North Carolina.
The Workplace of Naval Analysis funded this work.
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