Walking Robot

CNN.com - Robot walks, balances like a human - Apr 18, 2005

Walking robots are one of the harder robotic technical problems around, so this really is pretty impressive. The human walk is little more than a controlled fall forward, from one foot to the other. To walk, we imbalance ourselves forward, and then push our center of gravity up, forward, and left or right, using our legs. Forward is the direction we want to go in, up is countered by gravity, but in order to stop from falling on our side, we humans have to counter the left-right movement by using the opposite leg. If you recorded a human's center of gravity as he walked, and saw it from above, it would appear somewhere between a wave and a zigzag; and it's accomplished because we humans can detect center of gravity without extra sensors.

Robots have to have center of gravity pre-balanced, or have some mechanism to balance it. This greatly increases the complexity of a robot. Most robots get around it by not dealing with it, but because so much of our society is based on the concept of two-legged creatures, designing this is an interesting accomplishment.