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Robotics Technology

STriDER, a Three-Legged Walking Robot 105

Roland Piquepaille writes "In a short article, New Scientist reports that researchers at Virginia Tech University have developed a tripedal experimental robot. With its three legs, this robot, named STriDER — short for 'Self-excited Tripedal Dynamic Experimental Robot' — is actually more stable than 2- or 4-legged robots. As said another researcher, 'It's like a biped with a walking stick.' This robot is intended to deploy sensors and cameras in difficult-to-access areas."
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STriDER, a Three-Legged Walking Robot

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  • Great, now robots will have also three legs.
    • A White Zombie song? Reminds me of something that would be in Aeon Flux...
    • Did they really just say "Two legs good, three legs better"?

      Not again...

      I for one welcome our new three legged robotic overlords.
    • Re: (Score:3, Insightful)

      I'm not an expert on this - but I'm sure there is a good reason why 3 legged things aren't popular in nature.
      • by Falkkin ( 97268 )
        The lack of 3-legged things is an "unintended" side effect of the fact that bilateral symmetry is practically ubiquitous in animals (excepting sponges and cnidarians), and any animal with bilateral symmetry is going to end up with an even number of legs. Bilateral symmetry has many evolutionary "uses" aside from locomotion, so it's fair to presume that an odd number of legs *could* still result in efficient locomotion.

        Things with wheels aren't popular in nature either, but that doesn't mean wheels aren't e
        • Things with wheels aren't popular in nature

          But I say that they have to just put up with 'em. Uncivilised buggers.
        • "Things with wheels aren't popular in nature either, but that doesn't mean wheels aren't effective for locomotion."

          Actually if you consider the varied amount of terrain, wheels are impractical, they just don't have the wealth of terrain adaptability that feet and appendages provide.. like camels or amphibians.

          How many wheels can climb trees?
      • I don't know about you, but half the time I have 3 legs.
  • Now that would be a sight!

    But seriously, flipping 180 degrees with each step? That reduces the useful applications ...
    • But seriously, flipping 180 degrees with each step? That reduces the useful applications

      Not if the application you have in mind involves BEING COMPLETELY AWESOME, it doesn't.
  • I have a tape (yes, cassette tapes - remember those?) of a BBC Radio 4 science doc from 18 months or so ago which I taped for the bit where they interviewed Jim Bell & some other MER people, and also looked round the JPL robotics lab; they mentioned this one, and also something called ATHLETE (google it up) and another gizmo described as looking like a robotic spider with multiple articulated arms, intended for EVA work around the ISS or similar structures, whose name I forget. They were just proof-of-c
  • by u-bend ( 1095729 ) on Monday September 24, 2007 @03:21PM (#20733165) Homepage Journal
    "Self-excited?" Tripod? And we're not supposed to make naughty jokes about this?
  • by thesolo ( 131008 ) * <> on Monday September 24, 2007 @03:23PM (#20733183) Homepage
    Interesting concept, except that with the way it moves, it can't really walk in a straight line.

    Because it swings one leg outward from the rear to the front, it's always going to essentially be side-stepping a width that's in direct proportion to the length of its legs. If it starts in a position like <|, with two legs up front and one in the rear, and then swings the rear leg outward to position |>, the next step has to be to the left or right sides. It could every other stuff in reverse and zig-zag for the net effect of a straight line, but it wouldn't work well for very narrow spaces unless it could dynamically adjust the height of its legs.

    Nevertheless, I'd love to see one run at some point!
    • by thesolo ( 131008 ) *
      That should read, "It could take every other step", not "It could every other stuff". Whoops. :)
    • by falconx7 ( 447933 ) on Monday September 24, 2007 @03:51PM (#20733619)
      It's like flipping an equilateral triangle, it actually only needs the height of the triangle as a width to follow a path. the path it follows, as far as the legs are concerned, is straight. The central body does move in a zig-zag method, but that doesn't matter for navigating tight spaces.

      Basically, the directions it travels in are in line with one of it's sides, not in line with the direction one corner is pointing as you were trying to illustrate. Their videos on the article page rather nicely visualized it moving i a straight line.

      The main problem I see is that it can't do any turn by a a 60 degree turn. It can travel in 6 directions only... Makes me feel like I'm playing a hex board game...
    • And it's worth pointing out that it turns itself upside down every time it takes a step. This would, I think, end up being a real bear of a problem in a practical robot... sometimes the head's on the top... sometimes the head's on the bottom. It also has each of the three sides being the "front" alternately-- so, essentially, it has no front... Still, it's pretty darn cool.
      • Re: (Score:3, Funny)

        by FauxPasIII ( 75900 )
        > And it's worth pointing out that it turns itself upside down every time it takes a step. This would, I think,
        > end up being a real bear of a problem in a practical robot... sometimes the head's on the top... sometimes the
        > head's on the bottom. It also has each of the three sides being the "front" alternately-- so, essentially, it
        > has no front... Still, it's pretty darn cool.

        So just put a chaingun on all 3 surfaces and make sure the ammunition feed can handle being inverted. What's the probl
    • Interesting concept, except that with the way it moves, it can't really walk in a straight line.

      When I looked at the video, I thought, "WOW! Thats pretty cool how the body flips like that".

      Then, it came to me, that it sucks that the body flips like that. What kind of payload could you have on the thing when every step it took it was flipped upside down?

      Maybe I'm missing something, but I don't see a value added here.

      • Camera doesn't really care if it's upside down or downside up. Just flip the image in the viewscreen 180 degrees. Granted, it'll be a bit of bother when the viewpoint shifts some 20 odd centimeters up and down every now and then and the legs might be in the way of panorama. But I can see ways to adjust for that. (one camera per side of the triangle, mounted inside the body and you're done. Three legged recon unit.)
  • by jbeaupre ( 752124 ) on Monday September 24, 2007 @03:23PM (#20733189)
    Some guy in our neighborhood had one of these. I never saw it. But every time it snowed, tracks made by the 3 legged robot would begin showing up. What was really clever was how he molded animal paws on the feet to improve traction.
  • by jollyreaper ( 513215 ) on Monday September 24, 2007 @03:25PM (#20733213)
    Our new tripod overlords. My only question, are they HG Wells-style [] or John Christopher-style []?
  • by tonyreadsnews ( 1134939 ) on Monday September 24, 2007 @03:27PM (#20733259)
    I can't believe no-one made a joke about Half-Life 2 and the Combine's Striders.

    I wonder if Gordon is in on this project?
  • I'm curious what kind of practical applications this would have. As another poster mentioned, the robot flips every time it takes a step. This would probably make it difficult to have the power source in the central module connecting the legs as it would be too heavy (unless it was perfectly balanced, which might be a bigger issue).
  • Ulla! Ulla! (Score:5, Interesting)

    by The Queen ( 56621 ) on Monday September 24, 2007 @03:29PM (#20733305) Homepage
    JOURNALIST: Quickly, one after the other, four of the Fighting Machines appeared. Monstrous tripods, higher than the tallest steeple, striding over the pine trees and smashing them. Walking engines of glittering metal. Each carried a huge funnel and I realized with horror that I'd seen this awful thing before.

    A fifth Machine appeared on the far bank. It raised itself to full height, flourished the funnel high in the air - and the ghostly, terrible Heat Ray struck the town.
  • its Strider from Lord of the Rings lore, nickname of aragorn in around bree land and you know it.

    bastardly geeks geekizing all aspects of our culture....

  • 'It's like a biped with a walking stick.'
    4chan is already interested in images, please submit asap.
  • It's a mechanical Pierson's Puppeteer [], that's all.
    • It's a mechanical Pierson's Puppeteer, that's all

      Actually I was thinking about the story where the Ramans do everything in threes.

      • by mdenham ( 747985 )

        Actually I was thinking about the story where the Ramans do everything in threes.
        Yeah, if it's shaped like a ball with three legs and three "whips", it's a perfect imitation of the "spiders" from the Rama series.
      • Actually I was thinking about the story where the Ramans do everything in threes.
        Did anyone else read this and think "three packets of ramen, yummy!" :P
  • Rite...

    If it wears shoes???
  • roland again? (Score:3, Insightful)

    by Brett Buck ( 811747 ) on Monday September 24, 2007 @03:50PM (#20733591)
    You hot-shot computer geeks at /. ought to b able create a new story filter - that permits any story with the string of random letters "Roland Piquepaille" to be filtered out. As a public service, of course. Clearly the Ed's aren't up to the task.

    • by Inda ( 580031 )
      This is the second time I've mentioned this - I wish I could remember the correct answer...

      There is a greasemonkey or Firefox extension to filter Roland's stories.
  • 3 is more stable than 2 or four? Look, there is a point. It's lonely. Two points make a line. Three points make a plane. A fourth point would be restricted as to where it can be placed to stay on the level plane, and bad placement would...."break" your flat plane. Three points always make a flat plane. Four points are not so consistent.
  • Notice in the video where the guy watches with his hands on his hips whereas the girl instinctively reaches out as the device teeters forward? Will we have a whole generation of roboMoms?
  • by Dirtside ( 91468 ) on Monday September 24, 2007 @04:06PM (#20733851) Journal

    'It's like a biped with a walking stick.'

    Hm, I'd say it's more like a nine-legged dog that's had six legs removed.

    Seriously, does he think it's that difficult for people to conceive of something with three legs? :)
    • Re: (Score:3, Insightful)

      That's a pretty crummy analogy anyways. A biped with a walking stick has two primary limbs and shifts its weight to leverage the third assistant limb. All limbs are equivalent in the video, plus the mechanics look inefficient as hell. Swinging the entire body and one limb to take a step? And, a step that's angled away from your intended direction? Bah.
      • Re: (Score:2, Interesting)

        by slashbaby ( 261784 )
        Actually, it looks a pretty efficient way of using gravity to move. It's not much different than how you learned to walk, except that the robot keeps two legs stable instead of your one. In fact, the talking video chick says "this novel tripedal gate is highly energy efficient."
  • The school should *NEVER* be referred to as "Virginia Tech University"... ARGH!!! Yuck!!!

    --> BSEE, VPI&SU 1987
  • There's no such thing as Virginia Tech University... it's Virginia Tech or Virginia Polytechnic Institute and State University.
  • Correction... (Score:3, Informative)

    by gnownaym ( 705075 ) on Monday September 24, 2007 @04:15PM (#20734023)
    The full name of the school is "Virginia Polytechnic Institute and State University." "Virginia Tech" is an official trademark. "Virginia Tech University" draws angry, red-pen-toting alums.

    Just thought I'd let you know...
  • I've got a 3rd leg but it never occurred to me to use it for walking, oh wait....
  • I doubt this could honestly be called "more stable" than 2- or 4-legged robots, because during most of its stride, it is hanging off-center-of-gravity by two legs. This might be said to be more "stable" than most 2-legged strides, but 4-legged? I doubt it very much.

    Further, each step averages 30 degrees away from the desired direction of travel, so it is a very inefficient walk, as well.
    • Well, the stability of tripods is pretty well-established. Of course, you'd want to consider stability while stationary and while in motion. There's also a weight ratio to consider -- whatever metric of stability you choose, I bet you can maximize stability-to-weight with three legs rather than any other number.

      As another poster pointed out, the stability of three legs has a lot to do with the fact that any three (non-colinear) points describe a plane. With four legs, you'd have to engineer against the t
      • Static stability is not an issue here at all, since any well-designed bipod with feet, tripod, or quadripod will be reasonably stable at rest. We can just dispense with all of that. The only issue in question here is dynamic stability. Anything else is non-sequitur.

        The dynamic stability of tripedal motion has NOT been "well established". If it had, this would not be news. At all.

        When it comes to dynamic stability, that very point about 3 points making a plane (which should be considered kindergarten m
  • by Dan East ( 318230 ) on Monday September 24, 2007 @04:35PM (#20734299) Homepage Journal
    I like this one better:


    Dan East
  • BigDog [] by Boston Dynamics is already there.
    For those who haven't seen it, watch the video. The part where they try to kick it over is pretty impressive.
  • Interesting robot. However, why is this sponsored by the Navy? I could see if it had three fins, but it looks like its a landlubbing robot?
  • The first prototype stands 1.8 metres tall, while the latest incarnation is slightly shorter, at 0.9 metres.

    yeah...."slightly" shorter....
  • IANARS (I am not a robot scientist), but given that the body has to rotate 180 degrees with each step, I find it difficult to figure out how it can carry any significant load. It's really cool looking, but I believe that would affect its utility. Big time.
  • That was the most worthless video possible. First, they waste almost half of it explaining all kinds of irrelevant things. "The robot doesn't walk like Hollywood!" Why not just show the robot walking, so we can see for ourselves? Then a whole bunch of step-by-step still imagery showing how a computer model of the robot would appear in different stages of walking. Then, finally, some footage of the computer model walking. Then a bunch of half-assed brochureware footage of the computer model in paramilitary
  • Where the hell is Gordon Freeman?
  • ... I welcome our Martian overlords.
  • First [] thing [] I thought of when I saw Strider and tripod in the headline.
  • Who, instead of thinking about Half-Life 2, thought of The Tripods []?
  • This can be done with 4 legs, 2 front legs for stability while the body flips 180 degrees and 2 back legs flip under. This means straight lines, right angles, and more stability.
  • I thought it was an interesting concept, except for the fact the body flips over. That means you can't put a torso above said tripod.

    For years we've seen movies & video games show three-legged robots & critters walk around, but you've never seen the mechanics of it. The technical side of me was always curious how it could be done. If you have a standing tripod, the instant it raises a leg, you have an angled(ie not straight like a bipoed) footing for the remaining 2 legs. Add the offset center of g
  • by doti ( 966971 )
    With the body rotating like that on each step, it's no use for bringing me beer.

1 1 was a race-horse, 2 2 was 1 2. When 1 1 1 1 race, 2 2 1 1 2.