A Simpler, Gentler Robotic Grip

A new artificial hand shows promise for home robots and prosthetics.

Industrial robots have been helping in the factories for a while, but most robots need a complex hand and powerful software to grasp ordinary objects without damaging them.

Soft touch: This four-fingered robotic hand contains sensors that help it pick up a variety of objects. Credit: Leif Jentoft

Multimedia   See the sensor-embedded SDM hand pick up objects.   Watch an older video of the hand in motion.   Robotic Hand Grasps a Number of Objects

Researchers from Harvard and Yale Universities have developed a simple, soft robotic hand that can grab a range of objects delicately, and which automatically adjusts its fingers to get a good grip. The new hand could also potentially be useful as a prosthetic arm.

"When you start to bring robots into human environments, all of a sudden there's a big advantage for being compliant," says Charlie Kemp, an assistant professor at Georgia Tech who designs home-assist robots. "You can't always know what is where. You don't just want to push through the world and break something. You want to have the mechanics comply."

Other researchers have developed soft robotic hands, such as the Sensopac developed at Intel or Obrero created at MIT, but these are generally loaded with multiple types of complex sensors and motors, and require powerful algorithms to account for every joint and finger movement. In contrast, the new robotic hand has just a few sensors and a single motor, but can pick up a variety of objects with the flexibility of a human hand.

Aaron Dollar, an assistant professor at Yale University who led the work, notes that when reaching for an object, people do not normally use a rigid grasp, but keep their fingers relaxed, so as to avoid knocking the object over. Making the robotic hand flexible allows it to pick up objects even with minor calculation errors. Embedded sensors also allow the new hand to feel an object and adjust its grip. In much the same way, says Dollar, if you reach for a coffee mug with your eyes closed, you will feel around for the best grip before picking it up.

Story continues below

"So basically we can start off without knowing anything about the object and reach the hand forward and through this very simple algorithm, to build up a better understanding of where the object is located," says Dollar. The hand has recently been licensed by Barrett Technology, a company based in Cambridge, MA, that sells robotic hands for research.

"They've shown the hand is compliant, so you don't have to have it as precisely positioned as you do other types of hands," says Kemp of Dollar's work. "The robot doesn't have to know exactly where the object is, and in human environments, that's really valuable." He adds that a rigid grasp requires more precise control and execution--and therefore usually more computing power.