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DARPA LS3 quadruped plays follow the leader through mud puddles and more


December 20, 2012

No worse for wear, DARPA's LS3 lands in a mud puddle during a training exercise from the fall, 2012

No worse for wear, DARPA's LS3 lands in a mud puddle during a training exercise from the fall, 2012

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DARPA's robotic pack mule, the Legged Squad Support System (or LS3 for short) is now following orders and its master, going where no robot has gone before. In a recently published video, the impressive quadruped robot developed by Boston Dynamics climbs up and down hills, scrambles over logs, bobs and weaves through woods, and even takes an impromptu dip in a bog. Once outside the obstacle-ridden forest the LS3 picks up the pace with a somewhat inelegant gallop that betrays its mechanical nature.

Boston Dynamics' founder, Marc Raibert, has been described as the rock star of the robotics world. He made a name for himself at MIT, where he worked on some pretty amazing legged robots – some of which appeared in the background of a scene in the film adaptation of Michael Crichton's Rising Sun. Now his company is working on the follow-up to BigDog, a robot which hardly requires an introduction after its videos went viral a few years back.

According to DARPA "the Army has identified physical overburden as one of its top five science and technology challenges". Enter the LS3, nicknamed AlphaDog, designed to carry a squad's 400 pounds (181 kg) of gear for up to 20 miles (32 km) without stopping.

The LS3 produces ten times less noise than BigDog and features some other tweaks - like a barrel-shaped body - which allows it to easily roll over should it fall on its back or side. You can see just how effective this is in the latest video, when it accidentally stumbles and rolls down the side of a hill. It even lands on its feet despite falling into a fairly deep mud puddle.

Other improvements are demonstrated as well; it understands specific verbal commands and hand gestures, allowing soldiers to order the robot around in various situations. Its sensors also allow it to follow a leader even through a fairly dense, obstacle-ridden environment. A brief section in the video shows us the world from its perspective – a blocky facsimile similar to that of Google's driverless cars – which is accurate enough for the LS3 to find its way through the foliage. DARPA says it's smart enough to find its way to a designated GPS coordinate.

The LS3 quadruped's sensors give it a detailed real-time view of its surroundings, allowing it to navigate densely packed foliage

In more structured environments like urban areas, the LS3 is able to move much more quickly, revving up to a solid 7 mph (11.2 kph) trot. And despite relatively tight corridors, it knows when it can squeeze in with little room to spare. It's currently being tested at a military base, but next year it'll join a squad as part of the Marine Corps Advanced Warfighting Experiment.

If you're wondering how Marc Raibert earned his rock star status, let the following video speak for itself.

Source: DARPA via IEEE Spectrum

About the Author
Jason Falconer Jason is a freelance writer based in central Canada with a background in computer graphics. He has written about hundreds of humanoid robots on his website Plastic Pals and is an avid gamer with an unsightly collection of retro consoles, cartridges, and controllers. All articles by Jason Falconer


Derek Howe

I wonder how long it will take for the enemy to learn to yell "LS3 power down!" or something even more sinister ("LS3 trample your master!")


I am always a naysayer when it comes to robots with legs. I see millions of dollars in development and a lot of complexity.

Is this something a 17 year old former D student can repair in the field with minimal replacement parts in 3rd word country?

I see a task that an ATV could perform for 1/100th of the cost with better reliability and cheaper/more available replacement parts.


Until it meets an early IED.


All I ask of it is to identify the poison oak.

Mark A

re; Diachi

Walkers can go places that a wheeled vehicle can not. The reverse is not true.

The four legs appear to be identical and you could use the same actuators at all the joints and such to limit the number of different parts.

For the most part soldiers get jobs that suit their abilities and the best mechanic I ever met never got a grade better than a C- in his life.


Impressive, it's far more nimble than I would have expected. I think the ground contact surfaces will need to be improved thought to deal with different type of ground. As it is I think it would struggle with soft and slippery terrain.

Siegfried Gust

I don´t understand why this piece of crap would be any better than a real ass or mule. The best part is that a flesh and blood mule can feed itself and has all the built in intelligence required to climb steep hills, ford rivers, avoid obstacles and follow a leader. In addition, it is waterproof, you can butcher it to feed a hungry platoon and costs peanuts compared to this contraption.

I suppose the big advantage is that they can plug it in to the moon when it runs out of battery.

Joaquin Colgao

Hmmm - I seem to remember a wonderful quadruped capable of such feats...what was it called?...Oh yeah - a horse. How reliable and resilient will this be under fire? Any better than a horse? Besides - a horse can't be hacked or disabled by an EMP.


The number of mules that died during the Burma campaign in WWII is appalling this won't die of bug bites in three months.

This won't panic when it gets dinged or runs into something unfamiliar.


So many nay sayers. A horse or mule can be killed by a single bullet. Put some light weight armor on it and it will take a lot more to take it out. Also this thing doesn't get tired like a live animal will. Nor will it shy away from the sound of gun fire.

Another thing, this device could be loaded with missiles and be able to get into a better firing position than any of the troops, especially if they were pinned down.

This is a good piece of machinery.


Who says legs can go where wheels can't?

Lets see the LS3 go through mud like this: www.youtube.com/watch?v=qP1NNUm5P3E

The part where the LS3 rolls over in the video would be trivial most 4wd ATV's.

I would bet money on something like a Can Am XMR against this every time. Anyone who questions what wheels will climb hasn't seen competitive rock crawling and those are mostly contraptions thrown together with off the shelf parts by hobbyists. Here is an example of that: www.youtube.com/watch?v=KDOdny710vw

If you had a bunch of budget money to spend you could even bolt a couple arms to the top of a wheeled vehicle to be used to help give itself a push or flip itself back over if it rolls.

I think it would also be harder for a legged vehicle to use the assistance of a winch to get itself unstuck because it uses an algorithm to anticipate leg placement and it would have to adjust for the force of the winch and a wheeled doesn't need to.

I can think of a lot of other problems like weight. I can push a car by myself because it doesn't require that much energy to move it forward because I don't have to lift the weight to move it forward. This is not the case with legs. They have to constantly lift the weight in addition to moving forward so a much greater amount of energy is needed for travel as load increases.

This is the reason I can push a 5,000 lb car but carrying 100 lbs of gear sucks. Because I have legs and the car does not so there is a disproportionate amount of force required to perform the tasks.

Legged robots are at best too heavily based on science fiction and at worst bad science.


re; Diachi

There is no way a skid steer is going to climb rocks like that or the rock crawlers are going to turn in their own length. Wheeled vehicles are at a great disadvantage going across a minefield as well.

A hydraulic actuator requires no energy to hold its position.

At the beginning of the USofA civil war the chief of weapon procurement for the Union Army was of the opinion that breach loading rifles would cause soldiers to shoot too fast. I would love to see his reaction if someone presented him with an AK-47. ...................................................................................................

I should have mentioned earlier. Animals need daily rest horses will work themselves to death for you and once a mule decides that it has put in a solid day's work it takes an act of god to get it to put forth effort.


I'm with Slowburn on this one. Though it is a bit noisy, and would likely sink in deep mud. However, like a mountain goat, this thing can climb, trot, and navigate, on it's own, which your ATV's can not. It is a portable power source if needed, and can be used to shield fighters from incoming fire. (armor and sound proofing would help) It will not bolt, bite, or startle. And will take the load of the fighters and allow them to do what they do best. I understand it can also carry wounded soldiers out of the battle field to help on it's own.


So.....With all this incredible science and tech, US soldiers (and I am presuming their allies in a few years) are beginning to approach the mobility their enemies achieve with much cheaper real Donkeys (and you don't need a power point for a donkey).....I think this will change soldiers behaviours as well (do they protect themselves or the ridiculously expensive bit of kit?). I can see far greater, peaceful utilisations of this tech in the Civilian World.

Vincent Najger

also.....a horse/donkey will try REALLY hard NOT to fall on you or crush you...

Vincent Najger

Here is another LS3 Robot video: https://youtu.be/7s-YyPGsaB4

John Olesen
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