Robotic Gripper Runs on Coffee ... and Balloons

Robotic Gripper Runs on Coffee ... and Balloons

  9:03:00 AM    Science Lover

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The human hand is an amazing machine that can pick up, move and place objects easily, but for a robot, this "gripping" mechanism is a vexing challenge. Opting for simple elegance, researchers from Cornell University, University of Chicago and iRobot have bypassed traditional designs based around the human hand and fingers, and created a versatile gripper using everyday ground coffee and a latex party balloon.

Graduate student John Amend, left, and associate professor 
Hod Lipson with the universal robotic gripper. 
(Credit: Robert Barker/University Photography)

They call it a universal gripper, as it conforms to the object it's grabbing rather than being designed for particular objects, said Hod Lipson, Cornell associate professor of mechanical engineering and computer science. The research is a collaboration between the groups of Lipson, Heinrich Jaeger at the University of Chicago, and Chris Jones at iRobot Corp. It is published Oct. 25 online in Proceedings of the National Academy of Sciences.

"This is one of the closest things we've ever done that could be on the market tomorrow," Lipson said. He noted that the universality of the gripper makes future applications seemingly limitless, from the military using it to dismantle explosive devises or to move potentially dangerous objects, robotic arms in factories, on the feet of a robot that could walk on walls, or on prosthetic limbs.

Here's how it works: An everyday party balloon filled with ground coffee -- any variety will do -- is attached to a robotic arm. The coffee-filled balloon presses down and deforms around the desired object, and then a vacuum sucks the air out of the balloon, solidifying its grip. When the vacuum is released, the balloon becomes soft again, and the gripper lets go.

Jaeger said coffee is an example of a particulate material, which is characterized by large aggregates of individually solid particles. Particulate materials have a so-called jamming transition, which turns their behavior from fluid-like to solid-like when the particles can no longer slide past each other.

This phenomenon is familiar to coffee drinkers familiar with vacuum-packed coffee, which is hard as a brick until the package is unsealed.

"The ground coffee grains are like lots of small gears," Lipson said. "When they are not pressed together they can roll over each other and flow. When they are pressed together just a little bit, the teeth interlock, and they become solid."

Jaeger explains that the concept of a "jamming transition" provides a unified framework for understanding and predicting behavior in a wide range of disordered, amorphous materials. All of these materials can be driven into a 'glassy' state where they respond like a solid yet structurally resemble a liquid, and this includes many liquids, colloids, emulsions or foams, as well as particulate matter consisting of macroscopic grains.

"What is particularly neat with the gripper is that here we have a case where a new concept in basic science provided a fresh perspective in a very different area -- robotics -- and then opened the door to applications none of us had originally thought about," Jaeger said.

Eric Brown, a postdoctoral researcher, and Nick Rodenberg, a physics undergraduate, worked with Jaeger on characterizing the basic mechanisms that enable the gripping action. Prototypes of the gripper were built and tested by Lipson and Cornell graduate student John Amend as well as at iRobot.

As for the right particulate material, anything that can jam will do in principle, and early prototypes involved rice, couscous and even ground- up tires. They settled on coffee because it's light but also jams well, Amend said. Sand did better on jamming but was prohibitively heavy. What sets the jamming-based gripper apart is its good performance with almost any object, including a raw egg or a coin -- both notoriously difficult for traditional robotic grippers.

The project was supported by the Defense Advanced Research Projects Agency.

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Particulate Matter from Fires in the Amazon Affects Lightning Patterns

Particulate Matter from Fires in the Amazon Affects Lightning Patterns

  11:43:00 PM    Science Lover

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Native Americans used smoke signals to indicate danger, and a white plume is sent up by the Vatican when a new Pope is chosen. Now, a new research project by Tel Aviv University researchers and their colleagues shows that where there's "smoke" there may be significant consequences for local weather patterns, rainfall and thunderstorms.

Lightning. Scientists researched data on lightning patterns in the Amazon to show how clouds are affected by particulate matter emitted by the fires used for slash-and-burn foresting practices. Researchers found that while low levels of particulate matter actually help the development of thunderstorms, the reverse is true once a certain concentration is reached -- the particles then inhibit the formation of clouds and thunderstorms. 
(Credit: iStockphoto/Chee Ming Wong)

In a new study, Prof. Colin Price, head of Tel Aviv University's Department of Geophysics and Planetary Science, researched data on lightning patterns in the Amazon to show how clouds are affected by particulate matter emitted by the fires used for slash-and-burn foresting practices. His findings, recently published in the journal Geophysical Research Letters, could be used by climate change researchers trying to understand the impact of pollution on global weather patterns.

Along with colleagues at the Weizmann Institute and the Open University in Israel, Prof. Price demonstrated how pollution's effects on cloud development could negatively impact our environment. While low levels of particulate matter actually help the development of thunderstorms, the reverse is true once a certain concentration is reached -- the particles then inhibit the formation of clouds and thunderstorms.

"The clouds just dry up," he says.

Lightning strikes to the center of the issue

Scientists have known for some time that man-made aerosols affect cloud formation, but specific scientific findings have been inconclusive. How clouds and storms change in response to air pollution is central to the debate about climate change and global warming, since clouds have a general cooling effect on the Earth's climate.

But how man-made pollution impacts clouds, rainfall and weather patterns remains poorly understood, and natural particulates, such as those generated by Iceland's recent volcano eruptions may add to this effect. The thick volcanic ash cloud absorbs solar radiation, heating the upper atmosphere, similar to the forest fire smoke, and can hence also impact the development of clouds and rainfall, Price said.

While studying the climatology of the Amazon forest during its annual dry season, the researchers noticed how thousands of man-made forest fires injected smoke into the atmosphere. Since thunderstorms still occur during the dry season, it was the perfect opportunity for studying the effects of these particulates on thundercloud development.

Cloud droplets form on small particles called "cloud condensation nuclei" (CCN). As the number of CCN increase due to the fire activity, the lightning activity increased in the storms ingesting the smoke. More CCN implies more small droplets that can be carried aloft into the upper parts of the cloud where lightning is generated. Increased lightning activity generally also implies increasing rainfall over the Amazon. But when particulate matter became too dense, they observed, clouds didn't form, and the lightning activity in thunderstorms diminished dramatically.

Seeking answers to vital questions

These results may have significant implications for polluted regions of the world that rely on rainfall for agriculture and human consumption. "One of the most debated topics related to future climate change is what will happen to clouds, and rainfall, if the earth warms up," says Prof. Price, "and how will clouds react to more air pollution in the atmosphere?"

Clouds deflect the sun's rays, cooling the Earth's climate. If we change the duration of cloud cover, the aerial coverage of clouds, or the brightness of clouds, we can significantly impact the climate, Prof. Price and his colleagues explain. And too many aerosols may have disastrous impacts on rainfall patterns as well.

Air pollution from car exhausts and smokestacks at power plants and factories contribute to increasing particulate matter in our atmosphere. This is the first study of its kind that uses lightning as a quantitative way to measure the impact of air pollution on cloud development over a large area, and across a number of years.

"Lightning is a sensitive index to the inner workings of polluted clouds over the Amazon Basin," concludes Prof. Price.

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