[NickHoff]

In general no, single actuators move in one dimension and then only in one direction. In humans we have muscle pairs, one contracts to open the joint and the other contracts to close the joint. Of course you can do the same thing with artificial actuators, but you're right, the really interesting stuff happens when you have lots of "actuators" (like a sheet that has a hundred individually inflatable cells) or the material that the actuators are embedded in folds in an interesting way. The properties of the skeleton have as much to do with the dynamics of the robot as the actuators do.

[YeGoblynQueenne]

Thanks for answering. I looked at the video again and I can see that a couple of setups use multiple muscles- that's what you're talking about I think. I'm guessing that it's going to be a lot easier to wrap a hundred individual muscles of this kind around an artificial skeleton than it is with "hard" ones.

I wonder also what all this means for more, let's say, traditional robots- like the ones we often see from Boston Dynamics. I guess it's still early to say but if I understand this correctly, people can now make cheap, light robots. Where does that leave heavy, expensive ones?

It's not a rhetorical question- Ferrari and McLaren didn't hang up their spanners just because Toyota and Datsun sell lots of cheap cars...