Robot Knifefish Can Swim In Any Direction

A robot modeled off of the ghost knifefish is capable of moving in any direction with a single long fin

1 min read
Robot Knifefish Can Swim In Any Direction

Bio-inspired robots are an awesome idea, since they take aspects that evolution has been refining for however many bajillions of years and put them into practice giving robots new capabilities. Northwestern University has created a robot called GhostBot modeled on the black ghost knifefish, which uses one single horizontal fin to propel itself forwards, backwards, and even straight up:

[vimeo //vimeo.com/moogaloop.swf?clip_id=18894865&server=vimeo.com&show_title=0&show_byline=0&show_portrait=0&color=00adef&fullscreen=1&autoplay=0&loop=0 expand=1]

Pretty cool, right? Here's how it works:

Observations revealed that while the fish only uses one traveling wave along the fin during horizontal motion (forward or backward depending on the direction on the wave), while moving vertically it uses two waves. One of these moves from head to tail, and the other moves tail to head. The two waves collide and stop at the center of the fin.

The team then created a computer simulation that showed that when these “inward counterpropagating waves” are generated by the fin, horizontal thrust is canceled and the fluid motion generated by the two waves is funneled into a downward jet from the center of the fin, pushing the body up. The flow structure looks like a mushroom cloud with an inverted jet.

To get a sense of the potential of this kind of mobility system, check out a video of the actual fish:

[youtube https://www.youtube.com/v/geajxS37mgg?fs=1&hl=en_US&rel=0 expand=1]

That's a pretty impressive adaptation, if you ask me, and effectively puts conventional thrusters to shame.

[ Northwestern ] VIA [ Fast Company ]

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The Bionic-Hand Arms Race

The prosthetics industry is too focused on high-tech limbs that are complicated, costly, and often impractical

12 min read
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A photograph of a young woman with brown eyes and neck length hair dyed rose gold sits at a white table. In one hand she holds a carbon fiber robotic arm and hand. Her other arm ends near her elbow. Her short sleeve shirt has a pattern on it of illustrated hands.

The author, Britt Young, holding her Ottobock bebionic bionic arm.

Gabriela Hasbun. Makeup: Maria Nguyen for MAC cosmetics; Hair: Joan Laqui for Living Proof
DarkGray

In Jules Verne’s 1865 novel From the Earth to the Moon, members of the fictitious Baltimore Gun Club, all disabled Civil War veterans, restlessly search for a new enemy to conquer. They had spent the war innovating new, deadlier weaponry. By the war’s end, with “not quite one arm between four persons, and exactly two legs between six,” these self-taught amputee-weaponsmiths decide to repurpose their skills toward a new projectile: a rocket ship.

The story of the Baltimore Gun Club propelling themselves to the moon is about the extraordinary masculine power of the veteran, who doesn’t simply “overcome” his disability; he derives power and ambition from it. Their “crutches, wooden legs, artificial arms, steel hooks, caoutchouc [rubber] jaws, silver craniums [and] platinum noses” don’t play leading roles in their personalities—they are merely tools on their bodies. These piecemeal men are unlikely crusaders of invention with an even more unlikely mission. And yet who better to design the next great leap in technology than men remade by technology themselves?

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