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Stanford's flying fish glider bests ordinary jumping robots

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May 28, 2013

Researchers at Stanford University have built a machine which jumps and glides like a flyi...

Researchers at Stanford University have built a machine which jumps and glides like a flying fish (Photo: Shutterstock)

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Researchers at Stanford University have developed a small "aircraft" that resembles a flying fish which can jump and glide over a greater distance than an equivalent jumping robot. Using a carbon fiber spring to take off, the jumpglider has a pivoting wing that stays out of the way during ascent, but which locks into place to glide farther on the way down.

Like flying snakes, squirrels and fish, the gliding aces of the Animal Kingdom, the ability to glide affords the machine certain advantages over its "ballistic jumping" peers. A gliding robot (and we use the term robot loosely, as the jumpglider is not an autonomous sensing machine) can travel a greater distance, land more gently, and, if necessary, adjust its launch angle without greatly compromising distance. A slippery launch surface favors a steeper jump, for example.

The challenge during take-off and ascent is to reduce drag as much as possible. Jumpglider's wing is free to pivot on the way up so that it naturally aligns with the direction of travel. At peak altitude, the wing locks into place using simple magnets on the wing and the body.

The researchers used typical airspeeds resulting from a jump launch to optimize wing design to maximize the ratio of lift to drag. The team arrived at a 70-cm (28-inch) wing for the 30-g (1-oz) prototype. Weight has been kept to a minimum by using balsa wood for the frame and a carbon fiber and ProFormance foam wing.

The machine's jumping and gliding mechanism

Analyzing the jumpglider's performance with a high-speed camera, the researchers found that though the jumpglider cannot jump as high as a simple ballistic jumper of the same weight using the same energy due to having some drag inherent in the design, it was able to jump farther horizontally thanks to its gliding descent. The gains made varied with the launch angle, traveling 40 percent farther at 58º and 20 percent farther at 45º. However, as researcher Alexis Lussier-Desbiens highlights to Gizmag, "the optimum jump angle of a ballistic jumper […] is fixed at 45º, which means that significant amount of friction is required to achieve that maximum theoretical jumping distance." The jumpglider is not so restricted.

Despite reports to the contrary, Lussier-Desbiens emphasizes the jumpglider's lack of autonomy. "Currently, the spring is manually loaded and the robot can't reload its spring by itself," he tells Gizmag. "This is something we will work on in the future, but demonstrating autonomous operations wasn't the focus of this work as many researchers have already demonstrated that on other jumping robots." Similarly, the prototype is not currently equipped with solar technology.

You can see the jumpglider in action in the video below.

Source: Biomimetics & Dextrous Manipulation Laboratory, Stanford University, Efficient Jumpgliding: Theory and Design Considerations (PDF)

About the Author
James Holloway James lives in East London where he punctuates endless tea drinking with freelance writing and meteorological angst. Unlocking Every Extend Extra Extreme’s “Master of Extreme” achievement was the fourth proudest moment of his life.   All articles by James Holloway
3 Comments

The pivot wing was invented over 100 years ago by a French designer but failed to impress the Wright brothers who promised to test it but didn't. So instead of a design that used the wing to establish stability by allowing the wing to move with the air currents, we got a fixed wing design with stability supplied by the pilot input.

I am intrigued by the use of a magnet to employ a transition from pivot to fixed wing. I wish they had explained how this worked.

Don Duncan
29th May, 2013 @ 01:19 pm PDT

I experimented with a similar mechanism on hangliders and ornithopters to enable takeoffs from a standstill. On piloted aircraft, the G's experienced by the sudden acceleration could cause trauma. I used a longer leaf spring to lessen these forces and a padded flying harness to absorb the shock to the pilot.

ezeflyer
29th May, 2013 @ 02:29 pm PDT

I would love to see them use a more exotic material for the wings. Something larger and more airfoils shaped. Perhaps some sort of aero gel. Like the new rubbery one they just came out with. I love simple designs and this couldn't get more basic.

Michael Mantion
29th May, 2013 @ 06:37 pm PDT
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