Record ground speeds achieved by robots in recent tests by the U.S. Department of Defense raise hopes more robots will be put to military use in the years to come.

Further improvements in tool design and production methods are likely to make more robots available for security than at present.

Robotic bomb disposal units already are a welcome addition to military inventories and help save lives.

Operating off a treadmill the legged robot Cheetah set speed records during tests at the Pentagon's Defense Advanced Research Projects Agency. A free-running prototype of the robot will be tested later in the year.

"The use of ground robots in military explosive-ordinance-disposal missions already saves many lives and prevents thousands of other casualties," DARPA said.

"If the current limitations on mobility and manipulation capabilities of robots can be overcome, robots could much more effectively assist warfighters across a greater range of missions."

The agency's Maximum Mobility and Manipulation -- "M3" -- program seeks to create and demonstrate significant scientific and engineering advances in robot mobility and manipulation capabilities.

The M3 program pursues four parallel tracks of research and development in tool design, production methods and processes, control of mobility and manipulation and prototype demonstration.

Recent tests showed the Cheetah robot galloping at speeds of up to 18 miles per hour, setting a land speed record for legged robots. The previous record was 13.1 mph, set in 1989. The Cheetah demonstration was carried out on a treadmill.

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 laboratory treadmill version is powered by an off-board hydraulic pump and uses a boom-like device to keep it running in the center of the treadmill. A free-running prototype will be tested later in the year.

The M3 program conducts basic research and isn't focused on specific military missions but the technology it aims to develop could have a wide range of potential military applications.

Legged robots, a recent innovation in robotics, have developed from bipedal models to robots that have four or six legs. The legs-over-wheels approach lends itself for use in all-terrain purposes as legs are more effective in an uneven environment than wheels.

An earlier quadruped called BigDog was created in 2005 by Boston Dynamics with Foster-Miller, the NASA Jet Propulsion Laboratory, and the Harvard University Concord Field Station.

The 3-foot long robot stands 2.5 feet tall and weighs 240 pounds, about the size of a small mule. It was capable of traversing difficult terrain, running 4 miles an hour, carrying 340 pounds and climbing a 35-degree incline.

BigDog was funded by DARPA in the hopes that it will be able to serve as a robotic pack mule to accompany soldiers in terrain too rough for conventional vehicles.