The Cheetah is a four-footed robot that gallops at 18 mph, which is a land speed record for legged robots. The previous record was 13.1 mph, set in 1989 at MIT. Cheetah development is funded by DARPA's Maximum Mobility and Manipulation program. This robot has an articulated back that flexes back and forth on each step, thereby increasing its stride and running speed, much like the animal does. The current version of the Cheetah robot runs on a high-speed treadmill in the laboratory 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. Later this year we plan to start testing a free-running Cheetah that will operate more naturally in the field.