Earlier this year, DARPA's Cheetah robot was shown running at speeds of up to 18 mph (29 km/h), setting a new land speed record for legged robots.
The machine has now been upgraded to achieve an astonishing 28.3 mph (45.28 km/h), demonstrated in the video below. By comparison, Usain Bolt's fastest speed during the 100-metre sprint was 27.78 mph (44.44 km/h).
For now, the Cheetah machine is tethered to an external power supply, and runs on an indoor treadmill. Next year, however, a new "Wildcat" robot will be developed that can run outdoors untethered:-