The Robotics and Mechanisms Laboratory (RoMeLa) of the College of Engineering at Virginia Tech has developed a unique robotic hand that can firmly hold objects as heavy as a can of food or as delicate as a raw egg, and be dexterous enough to gesture for sign language.
Named RAPHaEL (Robotic Air Powered Hand with Elastic Ligaments), the fully articulated robotic hand is powered by a compressor air tank at 60 psi and a novel accordion-type tube actuator. Microcontroller commands operate the movement to coordinate the motion of the fingers.
“This air-powered design is what makes the hand unique; as it does not require the use of any motors or other actuators, the grasping force and compliance can be easily adjusted by simply changing the air pressure,” said Dennis Hong, RoMeLa (http://www.me.vt.edu/romela/) Director and the faculty adviser on the project. RoMeLa is part of Virginia Tech’s department of mechanical engineering (ME).
The grip derives from the extent of pressure of the air. A low pressure is used for a lighter grip, while a higher pressure allows for a sturdier grip. The compliance of compressed air also aids in the grasping as the fingers can naturally follow the contour of the grasped object.
“There would be great market potential for this hand, such as for robotic prosthetics, due to the previously described benefits, as well as low cost, safety and simplicity,” Hong said. The concept has won RoMeLa first place in the recent 2008–2009 Compressed Air and Gas Institute. A judge on the panel said of the robotic hand, “It is a cutting-edge concept, and the engineering was no less than brilliant.”
Student team members, all ME majors, are:
- Colin Smith of Reston, Va., a senior
- Kyle Cothern of Fredericksburg, Va., a junior.
- Carlos Guevara of El Salvador, a senior
- Alexander McCraw of York, Pa., a senior
RAPHaEL is just part of a larger RoMeLa project: the humanoid robot known as CHARLI (Cognitive Humanoid Robot with Learning Intelligence). The hand is already on its second prototype design, with the newer model to be used by CHARLI. Once the newer model hand is connected to the larger body, it will be able to pick up — not just grasp and hold — objects, as would a person.