Robotics researchers have been working on walking robots for decades now. It's funny, considering most humans can do it by the time they're one year old, and quadrupeds like cows, deer, and horses can walk on day one. Part of the challenge is the simple fact that walking is essentially controlled falling. You shift your body ever-so-slightly in the direction you wish to go, and you put out your leg to prevent a face-plant. Along the way, you manage to move forward. The physics are slightly different for creatures on four legs, and each has its advantages and disadvantages.
This Yahoo article introduces us to WildCat, a gas-powered, four-legged robot developed by Boston Dynamics and partly funded by the U.S. Defense Advanced Research Projects Agency (DARPA), which is helping the private sector develop various kinds of robots for national defense. WildCat is the successor to Cheetah, which had to be kept connected to a computer and power source, but could run faster than Usain Bolt (on a treadmill, of course). This one is a bit slower, but has no tethers at all, which is a decided advantage.
Watch the cool video below!
Not all robots have to be big, of course. Back in high school, I did a report on "insect" robots developed at MIT, which were about a foot long and could potentially be sent to other planets, by the thousands. More recently, some advances have been made in the field of "nano" robots, which would be small enough to enter the human body and perform surgery at the cellular level. There is great hope that they will one day lead to a cure for cancer and other serious conditions.