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.