The artificial muscle is based on the concept of the Ancient Roman catapult. This innovative miniature actuator will be presented by its engineers on Saarland's Research Stand at the Hanover Trade Fair (Hall 2, Stand C 44) from April 17 to April 24.

As early as Roman times, ropes and bundles of sinews were used to create catapults for hurling huge boulders at enemies. The ropes were also twisted, i.e. turned around their own axis, so that tremendous energy was released when they were let go. This idea has been adopted by a group of researchers at Saarland University, under the direction of Hartmut Janocha, Professor of Process Automation, to develop robot hands which are able to grasp objects not only powerfully, but also gently. "The human hand is moved using muscles in the forearm. We therefore looked for a way in which we could also accommodate finger control and actuator in the robot's forearm, using the smallest possible components", said Professor Janocha, describing the challenge. Now the researchers are able to generate extremely high tensile forces in the smallest possible space using cords that are twisted by small, rapidly rotating electric motors.

"Extremely resilient polymer cords enable us to raise a five kilogram load 30 millimetres in a matter of seconds using only a small electric motor and a cord of 20 centimetres in length", Professor Janocha explains. Each robot finger, which is divided into three joints like the human finger, can be controlled extremely sensitively using the individual cord pulleys. Unlike earlier approaches which used cords rolled up on reels, the new solution is considerably more space-efficient. The minute electric motors are concealed in the robot's forearm, making it even more like the human being it is modelled on. "The minute electric motors rotate at a high speed and with a low torque of roughly 5 Newton millimetres," said Professor Janocha. "The use of twisted cords to connect miniature motors could also be interesting for other applications."

The scientists in Saarbrücken are carrying out research on robot hands as part of the DEXMART project, which is funded by the European Union and involves eight universities and research institutes in Germany, France, Italy and Great Britain. The project aims to equip robots with certain features which will enable them to act as personal assistants to humans in the home, the operating theatre or in industrial applications. Over a period of four years the European Union will invest more than Euro 6.3 million in this research project, which was launched in 2008.

Enquiries to:
Chris May
Laboratory of Process Automation (LPA)
Saarland University
Tel.: 0681 / 302-4188
Tel. 0511 / 89 49 71 01 (Telephone on exhibition stand)
c.maylpa.uni-saarland.de

www.dexmart.eu
www.lpa.uni-saarland.de