November 06, 2010
The best robotic hand is a... rubber sack full of ground coffee?
That's the short version of recent research on robotic grasp, reported by Kristen Minogue in a November 2, 2010 Washington Post story, which follows.
Scientists get a grip on grasping
It turns out that opposable thumbs aren't critical for getting a good grip. Neither are fingers. Scientists have created a robotic hand that can do such things as serve drinks and draw pictures even though it has no digits.
Fingers and thumbs work perfectly well for humans, says Eric Brown, a physicist at the University of Chicago. But on a robot they can be clumsy. The fingers slip. They grip too hard and break whatever they're trying to hold. And sometimes they don't grasp it at all. Then there are the complexities of manipulating 20-odd joints with a computer.
So Brown and his colleagues took a different tack. Their robotic hand, which they describe in a paper published online by the Proceedings of the National Academy of Sciences [PNAS], is a thin rubber sack filled with coffee grains or small glass spheres. When this hand comes in contact with an object, a small pipe sucks air from the sack, causing it to contract and mold to the object's shape. The contraction is small - a mere 1 percent change in volume - but that was enough to grab most objects the researchers tested. "It's very simple to control," notes Brown. "You don't have all these joints."
The hand works best on hard, dry, geometrically complex objects such as screwdrivers and toy jacks. It has more trouble with flat objects such as plastic disks and porous objects such as cotton balls. It also can't grip anything bigger than half its size: The biggest items the team picked up were one-gallon jugs of water. But the hand's true strength, according to John Amend, a Cornell University engineering student and a co-author of the paper, is its versatility. Aside from the limitations noted above, he says, as long as the gripper can grasp about a quarter of the object's surface, it can pick up just about any shape.
Scientists have been searching for a universal gripper for decades, and the idea of using a deflatable sack instead of fingers is not new, says Yale University physicist Corey O'Hern, who was not part of the study. But this is the first time the idea has been tested and quantified in so much detail. Compared with robotic fingers, he says, "this seems like a much better way to go."
O'Hern suggests solving the porous-object problem by making the sack stickier. But the problem there, he adds, is that letting go would be hard.
Amputees could benefit most from the technology, says Brown. Having a moldable hand that could hold a fork or swipe a credit card could drastically improve the quality of life for the tens of thousands of patients in the United States who have lost an arm. And without the need to manipulate eight fingers and two thumbs, he says, a gripper of this sort would be much easier to operate than many of the prosthetic hands currently on the market.
This article comes from ScienceNow, the daily online service of the journal Science, and can be read at news.sciencemag.org.
Here is the abstract of the scientific paper as published in PNAS.
Universal robotic gripper based on the jamming of granular material
Gripping and holding of objects are key tasks for robotic manipulators. The development of universal grippers able to pick up unfamiliar objects of widely varying shape and surface properties remains, however, challenging. Most current designs are based on the multifingered hand, but this approach introduces hardware and software complexities. These include large numbers of controllable joints, the need for force sensing if objects are to be handled securely without crushing them, and the computational overhead to decide how much stress each finger should apply and where. Here we demonstrate a completely different approach to a universal gripper. Individual fingers are replaced by a single mass of granular material that, when pressed onto a target object, flows around it and conforms to its shape. Upon application of a vacuum the granular material contracts and hardens quickly to pinch and hold the object without requiring sensory feedback. We find that volume changes of less than 0.5% suffice to grip objects reliably and hold them with forces exceeding many times their weight. We show that the operating principle is the ability of granular materials to transition between an unjammed, deformable state and a jammed state with solid-like rigidity. We delineate three separate mechanisms, friction, suction, and interlocking, that contribute to the gripping force. Using a simple model we relate each of them to the mechanical strength of the jammed state. This advance opens up new possibilities for the design of simple, yet highly adaptive systems that excel at fast gripping of complex objects.
More photos and information here.
A 2006 design by Yve Thelermont and David Hupton.
"... it appears to be only the top half of a clock, but the hands fully rotate."
"The hands give the appearance of tumbling off a cliff, alluding to the transience of time."
Powder-coated steel with aluminium hands.
Includes one AA battery.
8"W x 5.25"H x 2.75"D.
There was a time... when a clock appeared on bookofjoe at least weekly, sometimes more often than that.
I wonder why the fascination ebbed.
"Transcending the Material" — the art of Ben Cuevas
From his website:
"These photos document 'Transcending the Material,'
a mixed media piece that I created and installed while in residence at The Wassaic Project (an arts collective and residency program located in New York state).
The piece was exhibited at The Wassaic Project Summer Music and Arts Festival."
Bora Mici wrote: "The installation piece Ben Cuevas chose to showcase at The Wassaic Project features a knitted skeleton seated atop a pyramid of Borden’s condensed milk cans and a cloud of screen prints on plexiglass suspended above it.
The knitted skeleton is seated in the lotus position. The prints are of disembodied anatomical parts photographed in high resolution with diagrammatic illustrative overlays.
Ben conceives of the piece as a reference to material culture and Wassaic’s local history
(the Borden Company had a condensed milk factory in Wassaic) and a meditation on transcendence."
[via reader yogahz who added, "I'm only sorry I didn't see it on Halloween."]
Mini Screwdriver LED Key Ring
Can your key ring drive screws?
From the website:
It's like a toolbox in the palm of your hand.
Mini Screwdriver LED Key Ring goes wherever you do and is always ready to jump into action for a quick fix — use it to repair broken eyeglasses or remove the battery compartment from a child's toy.
There are five magnetic screwdriver tips contained inside.
The tool is easily removed from the key ring thanks to the detachable snap strap.
The super-bright LED light is powered by two replaceable button cell batteries (included).
"When a comic strip character retires, does their soul live on in the afterlife?"
Clip-On Tea Maker
Green or Black (the device — not your tea).
Helpful Hints from joeeze: What to do if a bee or a wasp flies into your moving vehicle
1. Roll down your windows
2. Let the insect exit on its own
This October 6, 2010 Charlottesville Daily Progress story relates what could happen should you choose to take more active measures.
Bid to swat bee causes 3-car wreck in Fluvanna
A woman trying to swat a bee that had flown into her car crashed into oncoming traffic Wednesday evening on U.S. 250 in Fluvanna County, causing a wreck that hospitalized three people, according to the Virginia State Police.
Claudette Egry of Orange yanked her steering wheel left when she tried to swat the bee and ran her Honda Civic into an oncoming Jeep Cherokee, said state police Trooper M. Covert. A Kia Spectra then ran into the back of the Jeep, he said.
All three drivers were taken to the University of Virginia Medical Center, Covert said. Egry was airlifted to the hospital, and the two other drivers were taken by ambulance, he said.
Egry has been charged with reckless driving, he said.
Covert said drivers who discover a bee in the car should roll down windows and attempt to let the bee exit on its own.
Love or Hate sticker
Just write in what's right for you.
Someone needs to take that upside-down heart and run with it.
$2.25 CAD (Desk and Stationary, page 4).