Wheeled Robot With Soft Rotary Motors Is 100% Squishy

There's a reason why you don't see rotary motors or joints in nature: at anything above the molecular scale, too much stuff has to be permanently attached to too much other stuff for any of it to be freely rotating in the way a mechanical wheel or axle is. The more bioinspiration you want to work into a robot, the more of an issue this becomes, which is why it's particularly impressive that researchers at Rutgers University in New Brunswick, N.J., have managed to put four silicone-based wheels with air-powered motors inside of them on a robot that's as soft as a Crocs shoe. Most squishy robots with pneumatic muscles exert force on the environment through bending: a pneumatic chamber that's constrained on one side will curve when inflated, which generates enough motion that robots can walk around on legs and pick things up with grippers. Directional motion like this is very common in nature: most of your muscles work this way, exerting force one way over a finite distance, in cooperative opposition to another muscle that exerts force the other way. You also have muscles that work together in peristalsis, in which synchronized contractions and relaxations generates a propagating wave.