When I was at case western, peeps were trying to get mechanical cockroaches to walk. Originally they used mini pneumatics (clippard minimatics cylinders with which I'm intimately familiar due to the backyard pneumatics craziness of my youth). The problem was with sticktion, moving mass and the fact that they have a constant force curve (and cylinders inherently suck on collapse due to lost area from the piston). They were experimenting with what was basically wire loom with rubber innertube inside it. When the innertube was inflated, it caused the woven plastic loom to shorten. It looked very much like black muscle too, when it was all attatched to a fake limb. Quite creepy.
