(Press-News.org) Most robots on a factory floor are fairly ham-handed: Equipped with large pincers or claws, they are designed to perform simple maneuvers, such as grabbing an object, and placing it somewhere else in an assembly line. More complex movements, such as adjusting the grasp on an object, are still out of reach for many industrial robots.
Engineers at MIT have now hit upon a way to impart more dexterity to simple robotic grippers: using the environment as a helping hand. The team, led by Alberto Rodriguez, an assistant professor of mechanical engineering, and graduate student Nikhil Chavan-Dafle, has developed a model that predicts the force with which a robotic gripper needs to push against various fixtures in the environment in order to adjust its grasp on an object.
For instance, if a robotic gripper aims to pick up a pencil at its midpoint, but instead grabs hold of the eraser end, it could use the environment to adjust its grasp. Instead of releasing the pencil and trying again, Rodriguez's model enables a robot to loosen its grip slightly, and push the pencil against a nearby wall, just enough to slide the robot's gripper closer to the pencil's midpoint.
Partnering robots with the environment to improve dexterity is an approach Rodriguez calls "extrinsic dexterity" -- as opposed to the intrinsic dexterity of, say, the human hand. To adjust one's grip on a pencil in a similar fashion, a person, using one hand, could simply spider-crawl her fingers towards the center of the pencil. But programming such intrinsic dexterity in a robotic hand is extremely tricky, significantly raising a robot's cost.
With Rodriguez's new approach, existing robots in manufacturing, medicine, disaster response, and other gripper-based applications may interact with the environment, in a cost-effective way, to perform more complex maneuvers.
"Chasing the human hand is still a very valid direction [in robotics]," Rodriguez says. "But if you cannot afford having a $100,000 hand that is very complex to use, this [method] brings some dexterity to very simple grippers."
Rodriguez and Chavan-Dafle will present a paper detailing their new approach in September at the International Conference on Intelligent Robotics and Systems.
Giving robotics a push
Rodriguez is currently exploring multiple ways in which the environment may be exploited to increase the dexterity of simple robotic grippers. In ongoing work, his group is looking for ways in which a robot might use gravity to toss and catch an object, as well as how surfaces like a tabletop may help a robot roll an object between its fingers.
In this most recent paper, the group investigates an approach to extrinsic dexterity called "prehensile pushing" -- exploiting fixtures in the environment to manipulate a grasped object.
"We're sort of outsourcing that dexterity that you don't have in the gripper to the environment and the arm," Rodriguez explains. "Instead of dexterity that's intrinsic to the hand, it's extrinsic, in the environment."
The researchers developed a model that describes the forceful interaction between a gripper, a grasped object, and different types of external fixtures such as corners, edges, or surfaces. To predict how an object may move as a gripper pushes it against a given fixture, the researchers designed the model to take into account various factors, including the frictional forces between the gripper and the object, and between the object and the environment, as well as the object's mass, inertia, and shape.
"Exploiting the environment"
In its current iteration, the model predicts the force a gripper must exert, on the object and the environment, to maneuver the object to a desired orientation. For instance, how tight should a robot grip a bar, and how hard must it push that bar against a point, to rotate the bar 45 degrees?
Rodriguez and Chavan-Dafle tested the model's predictions against actual experiments, using a simple two-fingered gripper to manipulate a short rod, either rolling, pivoting, or sliding it against three fixtures: a point, a line, and a plane. The team measured the forces the robot exerted to maneuver the rod into the desired orientations, and compared the experimental forces with the model's predicted forces.
"The agreement was pretty good," Rodriguez says. "We've validated the model. Now we're working on the planning side, to see how to plan motions to generate certain trajectories. One of the things we want to ask in the future is: How do you engineer fixtures in the environment so that a robot's motions are more reliable, and can be executed faster?"
Ultimately, Rodriguez sees extrinsic dexterity as an inexpensive way to make simple robots more nimble for a variety of uses: A surgical robot may push a scalpel against an operating table to adjust its grip, while a forensic robot in the field may angle a piece of evidence against a nearby rock to better examine it.
"Exploiting the environment is, and will be, important for robots and the research community," Rodriguez says. "Any applications where you have limitations in terms of payload or cost or complexity, areas like manufacturing, or surgery, or field operations, or even space exploration -- whenever you have a gripper that is not dexterous like a human hand, this [method] gives you some of that dexterity."
INFORMATION:
This research was supported, in part, by the National Science Foundation.
Additional background
ARCHIVE: Helping robots put it all together
http://newsoffice.mit.edu/2015/assembly-algorithm-for-autonomous-robots-0527
ARCHIVE: Getting a grip on robotic grasp
http://newsoffice.mit.edu/2014/getting-grip-robotic-grasp-0718
Washington, DC-Even before a child is conceived, the parents' exposure to environmental stressors can alter the way genes are expressed and ultimately harm the child's health when those genes are passed down to the next generation, according to a new article published in the Endocrine Society's journal Endocrinology.
Exposure to environmental stressors such as endocrine-disrupting chemicals, psychological stress and malnutrition may result in disadvantageous epigenetic "reprogramming" that can echo through multiple generations. When these stressors disrupt early developmental ...
WASHINGTON D.C., August 4, 2015 -- The following articles are freely available online from Physics Today, the world's most influential and closely followed magazine devoted to physics and the physical science community.
You are invited to read, share, blog about, link to, or otherwise enjoy:
1) IS PHYSICS RESEARCH ANOTHER CASUALTY OF UKRAINIAN CONFLICT?
David Kramer of Physics Today discusses the negative impact that the conflict in eastern Ukraine has had on physicists and students forced to relocate from their homes and universities.
"More than 25 universities and ...
More than 2 percent of all emergency department visits are now related to nontraumatic dental conditions, according to a study by researchers at Stanford University, the University of California-San Francisco, Truven Health Analytics and the federal Agency for Healthcare Research and Quality.
Although the expansion of Medicaid under the Affordable Care Act has made millions of low-income and rural Americans eligible for health insurance, many states don't provide dental coverage for adults under their Medicaid programs. Paying for dental insurance on the individual market ...
This news release is available in French. In summertime, bats are a common feature in the night sky, swooping around backyards to gobble up mosquitos. Bats also help with crops: they act as a natural pesticide by feeding on harmful insects.
But these winged mammals are now under threat. As agricultural intensification expands across the world, the conversion of their natural habitats has caused a dramatic decline in population. North American bats are also plagued with white-nose syndrome, an emerging infectious disease that's decimating their numbers.
"Many bat ...
The nonmedical use of prescription opioids (POs) has become an area of increasing public health concern in the United States and rates of use are particularly high among young adults. In the past decade, an emerging "epidemic" of nonmedical PO use has been reported. Among young adults, self-reported use is 11% and overdose deaths involving POs now exceed deaths involving heroin and cocaine combined. Sexual violence is also a serious problem in the United States receiving increased national attention, and the relationship between substance use and sexual violence is well ...
Irvine, Calif., Aug. 4, 2015 - Stacked in gravity-defying arrangements in the western San Bernardino Mountains, near the San Andreas Fault, granite boulders that should have been toppled by earthquakes long ago resolutely remain. In exploring why these rocks still stand, researchers have uncovered connections between Southern California's San Jacinto and San Andreas faults that could change how the region plans for future earthquakes.
In a study to be published online Aug. 5 in Seismological Research Letters, Lisa Grant Ludwig, associate professor of public health at ...
SAN FRANCISCO-- Stacked in gravity-defying arrangements in the western San Bernardino Mountains, granite boulders that should have been toppled long ago by earthquakes are maintaining a stubborn if precarious balance. In puzzling out why these rocks still stand, researchers have uncovered connections between Southern California's San Jacinto and San Andreas faults that could change how the region plans for future earthquakes.
In their study published online August 5 in Seismological Research Letters (SRL), Lisa Grant Ludwig of University of California, Irvine and colleagues ...
While cognitive abilities naturally diminish as part of the normal aging process, it may be possible to take a bite out of this expected decline.
Eating a group of specific foods known as the MIND diet may slow cognitive decline among aging adults, even when the person is not at risk of developing Alzheimer's disease, according to researchers at Rush University Medical Center. This finding is in addition to a previous study by the research team that found that the MIND diet may reduce a person's risk in developing Alzheimer's disease.
The recent study shows that older ...
Los Angeles, CA (August 4, 2015) The Journal of Endovascular Therapy (JEVT), official publication of the INTERNATIONAL SOCIETY OF ENDOVASCULAR SPECIALISTS (ISES), announces that is it today publishing the latest update of the Inter-Society Consensus for the Management of Peripheral Arterial Disease (TASC II),1 an internationally recognized set of guidelines for the management of patients with peripheral arterial disease (PAD). JEVT is a SAGE journal.
Originally published in 2000, the TASC document represents the collaboration of international vascular specialties involved ...
Washington, DC - August 4, 2015 - The pathogen, Listeria monocytogenes grows on refrigerated smoked salmon by way of different metabolic pathways from those it uses when growing on laboratory media. The research could lead to reduced incidences of food-borne illness and death, said principal investigator Teresa Bergholz, PhD. The research appears July 24 in Applied and Environmental Microbiology, a journal of the American Society for Microbiology.
In the study, the investigators showed that L. monocytogenes grows on cold smoked salmon by using different metabolic pathways ...
