The US Military last week unveiled a four-legged robot cheetah than can run faster than Usain Bolt.

This week it's unveiled something a bit slower - but probably a whole lot more useful.

The Boston Dynamics-built AlphaDog LS3 is the latest version of its famed robotic quadruped.

It's intended to help carry heavy loads on the battlefield, and is able to cope with pretty much all types of landscape including dirt, rocks and ice.

The new version is a lot quieter than the old one - which is handy since if you're trying to stealthily carry missiles through a battlefield you probably don't want the enemy to hear it from five miles away. It can go 20 miles without a recharge, carrying up to 400lbs of equipment.

It can move up to 5 miles-per-hour, and can speed up over difficult terrain.

The AlphaDog has been in development for years already, and is now entering a two-year testing period with the military's research wing (Darpa) and the Marines.

If it passes the eventual Advanced Warfighting Experiment test, the robot could finally enter military service.

Take a look below for a video guide through AlphaDog's slow, public evolution.

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  • Wildcat (2013)

  • LS3 (2013)

  • Petman (2013)

  • LS3 (2012)

  • Big Dog (2004-2010)

  • Sand Flea (2012)

  • Big Dog (2008)

  • BigDog (2009)

  • Robot Cheetah (2012)

  • AlphaDog (2012)