I'm curious here. If someone wanted to build a large, human sized walking robot... Would it be possible to get powerful enough servos to use as the actuators for the legs? We are talking about possibly 100 kg * cm of torque, at least (just guessing). Do they actually make servos that powerful? And if so, what kind of speed could be expected?
My guess is most people who build walker robots use linear actuators or systems that work with compressed air. These seem fairly expensive, however, and perhaps not as easy to control as servos can be.
If servos just aren't appropriate in this case... Do you believe there is an economical way of building a large scale walking robots with several degrees of freedom for each leg, or is that simply completely out of reach of amateurs?