Using pneumatic pistons and servos to power robots makes them fast and strong, but also bulky and extremely heavy. No one is going to mistake ATLAS for a real human being. To eventually create humanoid-looking robots like the Terminator we need to mechanically replicate every part of the human anatomy—starting with the muscles.
Researchers at the Suzumori Endo Robotics Laboratory at the Tokyo Institute of Technology started with an artificial human skeleton that was then covered in bundles of multifilament artificial muscles. Like real human muscles, the multifilament bundles contract and expand when an electrical current is applied, and by controlling different groups of these muscles at different times, the skeleton’s arms, legs, and head can all be made to move similar to how a real human can.