[zeestephen]

Currently, most humanoid robots have motors in their joints.

Thus, they have significant power, but much less control over direction and precise motions.

For instance, a traditional service robot might be able to support an elderly person when walking.

But Roboy, at some point, will be able to gently grasp a person's arm, exactly like a human being.

There's a video at the Kurzweil link that shows the "power tendons" up close.

But, no precise engineering description, if that's what you were hoping for.

[Pontiac]

Yes an engineering description is what I was looking for.

From the picture of the robot it looks to me like some kind of worm gear actuator (like an electric sash operator).

A worm gear would be smother than a conventional motor operator but would likely be much slower as well.