Now, robots with light-weight limbs that perform more human tasks more gracefully

A new hybrid fluid transmission has developed robot arms that were light enough to move swiftly and gracefully, yet with precise control.

Hydraulic systems often were used to actuate robots whose limbs needed to be light and to move fluidly. But conventional hydraulics were using a system of valves, which only transmitted power and were unable to absorb power from the environment.

Peter Whitney, an associate research scientist at Disney Research Pittsburgh has said that control also had not been as precise or as easy as was possible with electrical motors and electric motors meanwhile had their own problems, including heavy weight.

Whitney explained that the transmission allowed robot limbs to be light, strong and graceful while driving them with easily controlled, low-friction motors. The motors, which normally would add significant weight to the limbs, can be mounted on the robot body instead.

The transmission had consisted of antagonist pairs of rolling diaphragm cylinders - similar to traditional hydraulic cylinders, but sealed with a rubber diaphragm instead of sliding seals and valves. The result has been a system that could efficiently transmit power with little friction. Yet it would also be "backdriveable," capable of absorbing energy, as well as transmitting it.

The latter characteristic has allowed engineers to design limbs with th property to "give," an important feature as designers had contemplated new applications in the home, at work, or in entertainment venues that enable soft interactions between people and robots.

One possible application of a system made of non-ferrous material would be as a surgical robot compatible with use in a magnetic resonance imaging (MRI) device.

The transmission was highly efficient, enabling it to be operated in a passive, "puppet" mode or to be driven by a heavy, low-friction electric motor located off of the robotic limbs, in the robot's body.