Some dog owners spend years grooming their pups into strong, obedient alpha dogs. But scientists? They just build them.

A group of military-funded scientists from Boston has invented a dog-like robot, that can carry over 400 pounds on its back for 20 miles and on any sort of terrain. It uses computer vision and GPS to follow a leader, rather than require a remote-controlled driver to tell it where to go.

Nicknamed "AlphaDog," the prototype is the latest from the minds behind a four-year undertaking called BigDog, that's being developed by Boston Dynamics and funded by DARPA and the U.S. Marine Corps. AlphaDog is officially called "LS3," or the Legged Squad Support System.

Check out a video demo below. As you can see, AlphaDog can walk and trot over sharp rocks, albeit rather slowly. Escapist Magazine says it will take the robot 24 hours to cover 20 miles, though no re-fueling is needed. Clearly AlphaDog is designed more for walking alongside troops rather than outpacing anyone.

The video also shows two grown men pushing AlphaDog off its course, and once it does, the robot immediately resumes its original path. It can even get up after being knocked down. Pretty cool stuff.

LS3 will take 30 months to develop and is schedule for a "walk out" in 2012.

Boston Dynamics is also making robotic bugs that can squeeze through cracks, a reptilian robot that can scale walls and trees, and an anthropomorphic robot that will be used to test chemical protection clothing worn by the U.S. Army.