This video shows a demonstration of the “Cheetah” robot galloping at speeds of up to 18 miles per hour (mph), setting a new land speed record for legged robots. The previous record was 13.1 mph, set in 1989.
The robot’s movements are patterned after those of fast-running animals in nature. The robot increases its stride and running speed by flexing and un-flexing its back on each step, much as an actual cheetah does.
The current version of the Cheetah robot runs on a laboratory treadmill where it is powered by an off-board hydraulic pump, and uses a boom-like device to keep it running in the center of the treadmill. Testing of a free-running prototype is planned for later this year.
While the M3 program conducts basic research and is not focused on specific military missions, the technology it aims to develop could have a wide range of potential military applications.
It's hard to say what the government will do with a fast four-legged robot, but sf fans probably are thinking of the slamhound from William Gibson's 1986 novel Count Zero:
THEY sent A SLAMHOUND on Turner's trail in New Delhi, slotted it to his pheromones and the color of his hair. It caught up with him on a street called Chandni Chauk and came scrambling for his rented BMW through a forest of bare brown legs and pedicab tires. Its core was a kilogram of recrystallized hexogene and flaked TNT.
Update 07-Mar-2012: Another science-fictional prediction of this device can be found in the 1992 novel Snow Crash by Neal Stephenson. Remember the Rat Thing?
The body is Rottweiler-sized, segmented into overlapping hard plates like those of a rhinoceros. The legs are long, curled way up to deliver power, like a cheetah's. It must be the tail that makes people refer to it as a Rat Thing, because that's the only ratlike part - incredibly long and flexible...
The body converges to a sharp nose. In the front it bends down sharply, and there is a black canopy, raked sharply like the windshield of a fighter plane. If the Rat Thing has eyes, this is where it looks out.
Thanks to Vik at Diamond Age for pointing this out.