An EU funded project called SENSOPAC, which aims to develop new artificial robotic limbs, has been mimicking nature to take advantage of what has essentially stood the test of time. The newly built arm in many ways copies the human arm, and the developers are building a microchip brain that they hope to model on certain aspects of ours.
To mimic the skin’s sensing capabilities, researchers at the German Aerospace Centre (DLR), guided by physiology results from Umeå University, in Sweden, created a thin flexible material filled with a form of carbon whose resistance changes with pressure. This approach let them combine information from sensors in different parts of the skin in order to minimise the number of information-carrying wires.
“We can soon integrate hundreds of detector elements and get the information out with just five wires,” says van der Smagt [Patrick van der Smagt, coordinator of SENSOPAC –ed.]. “And we have the ability to distinguish between shape, the amount of force, and the direction of force.”
The human arm and hand can generate and control a remarkable range of force, from the delicate touch of a watchmaker to the power of a javelin thrower. Much of this range of force and finesse comes from the pairs of opposing muscles that control each joint.
Researchers at DLR took the same approach. The artificial arm they built and are now experimenting with uses a total of 58 motors in opposing pairs, coupled with non-linear springs, to control the arm.
The hand they have built is closely modelled on the human hand. It can snap its fingers, pick up an egg or carry a cup of coffee. Its fingers are moved by 38 opposing motors.
The researchers are currently using software to simulate important aspects of how the cerebellum processes and integrates information.
“It’s the first neural-network-based controller that can control the dynamics of a robotic system in its full operational range,” says van der Smagt.
In the next six months, they will be seeing how well this system can learn to control the arm.