A robotic hand developed at MIT provides its users something most people don't experience - the ability to use seven fingers on a single hand.
Two-handed tasks, like opening a jar or peeling a banana, become possible with just one hand, using the device. They could also be used to assist people with limited mobility, assisting with daily living activities, such as laundry and cooking.
The mechanism is worn on the wrist, adding extra (mechanical) fingers on near the thumb and pinkie. Movement is controlled by actuators in the device, following motions of the natural fingers. Pressure exerted by the robotic fingers is roughly equivalent to a human touch. Users can learn how hold on to an object with one set of fingers, while performing actions on it with others.
"This is a completely intuitive and natural way to move your robotic fingers. You do not need to command the robot, but simply move your fingers naturally. Then the robotic fingers react and assist your fingers," Harry Asada, engineering professor at MIT, said.
MIT researchers carefully studied the human hand, and the way we grip objects. Although the method by which we would grasp a bottle of water of a playing card may seem far different, the investigators found just two basic actions when humans grasp objects. One motion is pinching between thumb and fingers. The second is twisting fingers inward, like making fist. No matter what we are attempting to grasp, the study showed people use some combination of these two actions. Investigators wondered if the same idea would work with two additional fingers. They then proceeded to build a device to test that theory.
Faye Wu, a graduate student of Asada, tested the mechanism, reaching for objects around the lab, while a computer measured her actions. She held on to various objects, such as bottles, boxes and a football, measuring angles between fingers using several techniques. Analysis of the motions reveled Wu used just two or three basic moves, regardless of the shape of the object Wu was handling.
"With an object that looks small but is heavy, or is slippery, the posture would be the same, but the force would be different, so how would it adapt to that? That's the next thing we'll look at," Wu stated in a press release issued by MIT.
Future devices based on this research could include wearable robots - bracelets or watches, with arms that come out only when needed, then hide back in their housing.
Development of the robotic hand with seven fingers was announced at the Robotics: Science and Systems conference, held in Berkeley, California.