The typical soldier can only carry about 100 lbs. worth of gear, but not indefinitely. DARPA’s (Defense Advanced Research Projects Agency) new robotic mule, however, can carry 400 lbs. of gear and never get tired — and it can do it with a surprising degree of agility. Physical overburden of soldiers is one of the top five biggest challenges for the U.S. army, according to DARPA, and a semi-autonomous legged robot, officially named the Legged Squad Support System (LS3), might be one way of fixing that problem. In the video above, the LS3 prototype (original developer Boston…

