Motion System Design
Robotic hand offers light touch

Robotic hand offers light touch

The Robotics and Mechanisms Laboratory (RoMeLa) of the College of Engineering at Virginia Tech, Blacksburg, Va., has developed a robotic hand that can hold objects as heavy as a can of food or as delicate as an egg, but is dexterous enough to do sign language. Named RAPHaEL (Robotic Air Powered Hand with Elastic Ligaments), the hand is powered by a compressor air tank at 60 psi and an 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,” explains Dennis Hong, RoMeLa director.

The grip derives from the extent of air pressure. 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 is a 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 ( (CAGI)’s Innovation Award Contest, with team members sharing $2,500 and the College of Engineering receiving a separate $8,000 monetary award.

Related Links:

Compressed Air and Gas Institute

Robotics and Mechanisms Laboratory, College of Engineering, Virginia Tech

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