A robotic \"pack mule\" being developed for the U.S. military has had a field test, observed by military officers and defense officials, its developers say. The \"mule,\" or Legged Squad Support system, developed by the Defense Advanced Research Projects Agency, was demonstrated Monday for the Commandant of the Marine Corps, Gen. James F. Amos, and DARPA Director Arati Prabhakar, the DARPA website reported. Two functioning prototypes have been tested to simulate what they could one day experience while carrying gear for a squad of Marines or soldiers. The goal of the LS3 program is to demonstrate that a legged robot can unburden dismounted squad members by carrying their gear, autonomously following them through rugged terrain, and interpreting verbal and visual commands, officials said. \"The vision for LS3 is to combine the capabilities of a pack mule with the intelligence of a trained animal,\" Army Lt. Col. Joe Hitt, DARPA program manager, said. In the most recent test conducted in Virginia woods, the LS3 prototype underwent trotting and jogging mobility runs, a perception visualization demonstration and a soldier-controlled autonomy demonstration. \"The LS3 has demonstrated it is very stable on its legs, but if it should tip over for some reason, it can automatically right itself, stand up and carry on,\" Hitt said. \"LS3 also has the ability to follow a human leader and track members of a squad in forested terrain and high brush.\"