A robot's mass, therefore the energy required to move it, varies as the cube of its height. So given linear scaling of power with height, a giant robot is going

A robot's mass, therefore the energy required to move it, varies as the cube of its height. So given linear scaling of power with height, a giant robot is going to move more slowly than a human-sized one. In order to have a giant robot that moves fast, we have to solve for how to store, transfer, and use the vast amounts of power needed. My favorite solution comes from Evangelion: tether the robots on giant extension cords.