(CNN) -- The military's robotic beast of burden went out this week for another stroll, demonstrating advancements in the way it moves through real-world environments.
The LS3, first revealed in February, is designed to carry heavy loads for troops in the field -- up to 400 pounds worth of equipment.
In the footage released by the Defense Department's research and development arm, two of the mule-like robots can be seen navigating hilly terrain with relative ease, sidestepping rocks and getting up from a sitting position.
The new and improved version of the LS3 is roughly 10 times quieter than what was seen earlier this year and has the ability to "easily transition" between speeds ranging from 1 to 7 mph, "showing the versatility needed to accompany dismounted units in various terrains," said Army Lt. Col. Joe Hitt, a program manager for the Defense Advanced Research Projects Agency (DARPA).
The robot, which is being developed to have the ability to recognize basic voice commands, such as "stop," "come here," "sit," or "go over there," is able to follow a human leader and track members of a squad in forested terrain and high brush, according to DARPA.
"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," said Hitt. "The vision for LS3 is to combine the capabilities of a pack mule with the intelligence of a trained animal."
The agency had previously designed a similar four-legged robot called BigDog, which demonstrated to the research group that a "legged" design would be able to handle harsh terrain.
"BigDog was about mobility. Can we have a four-legged system navigate terrain the way soldiers navigate," Hitt said earlier this year. "We took BigDog's legs and put them on a platform three times the size and gave it eyes so that it could see its terrain."
The LS3 is smarter and stronger than its predecessor, which was able to carry only 100 pounds.
Onboard sensors allow LS3 to perceive obstacles in its environment, differentiating between a rock and a tree for example, and give the robot the capability to plan a different route.
Testing on the robot is planned to continue for two years, at which point the LS3 will be embedded with a Marine squad.