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Robotics Technology

Smarter Robot Arms 52

RogerRoast sends this quote from the MIT News Office: "As intuitive as it seems to a human being, spontaneously planning a trajectory around obstacles in free space is a monstrously complex computation. As a consequence, most motion-planning algorithms give up on the idea of finding the most efficient path between the robot’s initial state and its goal, settling for any path that won’t introduce collisions. [Researchers at MIT] have built a new robotic motion-planning system that calculates much more efficient trajectories through free space. ... Not only do robots guided by the system move more efficiently, saving time and energy, but they also move more predictably (PDF), a crucial consideration if they're to interact with humans."
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Smarter Robot Arms

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  • I have small children (up to 9) who don't seem very good at path finding. They're constantly going around the house in the most inefficient manner possible. Humans aren't that good at it either.

    • OK, let me understand this: you have children, not sure how many but max. 9, and they all circle your house, not finding the door? Fascinating! ;)

      • Fascinating enough for you to comment.

      • by mjwx ( 966435 )

        OK, let me understand this: you have children, not sure how many but max. 9, and they all circle your house, not finding the door? Fascinating! ;)

        Clearly one has never lived with children sub age 10. They can be relied upon to find coffee tables, sweets and their sisters hair but that's about it.

      • 9 isn't the max. They could have had twins, triplets, or even more. But then again 10+ pretty much guarantees you a reality show.
      • 9 = max age, not max quantity
    • by Anonymous Coward

      can't blame you since the summary is a bit misleading, but this is not really about "path finding" in the sense of navigating a body around an environment, it's about efficient movement of a manipulator at the end of a robot arm to get to it's target. Every joint that introduces a degree of freedom (this robot had 7 DOF arms) makes that calculation more difficult.

      Closest analog I can think of is something like a back hoe operator. The difference between a good one and someone just learning is huge in terms

      • I was at an industrial robotics trade show years ago, and there was one spray-painting an auto bumper that amazed me how gracefully it moved; at the end of a swing left-to-right, it turned its wrist at the same time it reversed the arm direction. The only word I could apply was "graceful". Later, I found out it had been trained by a human operator, so it was just mimicking what a human spray-painter with years of practice would do.
    • I thought your comment was pretty funny. Unfortunately you had a bunch of complete shitheads (especially AC) responding.
    • Your children are in Roomba mode. Find the instruction manual and reset them.
    • "As intuitive as it seems to a human being, spontaneously planning a trajectory around obstacles in free space is a monstrously complex computation"

      I was going to say a similar thing; observe any major highway in any major city in the USA and you will realize that many many people are absolutely terrible at "planning a trajectory around obstacles in free space"... So bad that it causes as many as 90 deaths *every day*.

      • by hitmark ( 640295 )

        Not helping that our sensory processing is not really built for anything beyond a walk. Running, much less driving a vehicle at highway speed, can't be properly processed beyond a straight and flat path.

    • You think they are being inefficient because you don't understand the constraints; in particular any carpeted are of floor is "red hot lava" and sofas are bouncy, allowing "slingshot" style trajectories that would be the envied by NASA.
      If your children are not human, what does that make you ?
  • by Animats ( 122034 ) on Friday September 23, 2011 @12:26PM (#37493056) Homepage

    That's a neat result. I used to work on that problem. Today's solutions use a lot more compute power, but now that's available. Early approaches to this problem worked by treating it as a maze problem in N-dimensional configuration space and running a maze solver. Latoumbe at Stanford was behind a lot of that. That approach became combinatorialy infeasible as N increased. Newer techniques are more like a random greedy search. That works, but the paths aren't all that great. This latest solution seems to improve on random greedy search. That makes sense.

    • Is that an N-dimensional matrix search that uses + in the regular expression?

      • by Animats ( 122034 )

        No, it's an N-dimensional configuration space. This is a variation on the Piano Mover's Problem. []

        Visualize getting a point-sized object through a maze. The maze can be treated as a graph, with junctions as graph nodes. All dead end links and closed subgraphs not containing the endpoints can be discarded. What remains contains a usable path. Then you use a path finding graph algorithm. If links have costs, there are ways to find an optimal or (with much less work) a near-optimal solution.

        Now consider get

    • by SnowZero ( 92219 )

      Latoumbe at Stanford was behind a lot of that.

      In a research family tree point of view, he's behind this too. The MIT algorithm is a modification of RRT that instead of using one-connectedness uses k-connectness like PRM. RRT is from LaValle and Kuffner, who were Latoumbe's students at Stanford. PRM is from Lydia Kavraki, who was also Latoumbe's student at Stanford.

      The PR2 video was kind or irksome, because they chose the very first version of RRT (circa 2000) to compare against their new algorithm, rather than a number of variants that became availa


    Save your mod-down points folks, you know it had to be done.

  • Sex lives of many /.ers improved.

    Rule 34 once again proven.
  • Darn it, I bought this inexpensive prosthetic arm from a bootlegger/bootarmer somewhere in Asia and sometimes it flails uncontrollably for between 0.5 and 2 seconds. I'm truly sorry it spilled your snack and you missed that scene. May I compensate you for the wasted theater popcorn? FWIW, my wife can't sleep in the same bed with me if I've forgotten to remove it, if that's any consolation.

    • The phrase "as hell" has been so over-used that it can mean anything and is therefore meaningless.

      The phrase "as hell" has been so over-used that it can mean anything and is therefore meaningless as hell.
      • Excellent revision to my "meaningless-as-hell" .sig!

        However, if it's that meaningless, wouldn't it also be as meaningful as hell? I don't want to perpetuate the redundancy of its meaninglessness when it's equally as meaningful. Heh. Oh, ouch. I really need to wake up before I type myself into a lake of logorrhea.

        Thanks for the comment :)

  • the Robot Arms Apartments, you optimal trajectory to high-rise comfort.

  • the algorithm they're so proud of besting seems pretty crappy.

    • by Fned ( 43219 )

      It only seems that way because you're super-good at it.

      (Apologies if it turns out you're a klutz)

      • i guess i don't understand why this robot behaves so bizarrely [with the simpler algorithm] when there are no shortage of videos of robot arms catching tennis-balls and such.

        as an undergrad i wrote a very simple reach-planning algorithm for a robot arm with N joints which seems like it would outperform the simpler of these algorithms.

        i must be missing something.

        • by Fned ( 43219 )

          That ball catching thing isn't the same thing at all, it tracks the hand and the ball to points in space.

          AFAIK, it can't detect obstacles in its space and figure out the most efficient way to move the hand from point A to point B without any part of the arm hitting any of the obstacles.

          It's the path-finding part that's tricky.

    • Having some understanding of the field, I'm normally pretty forgiving about the problems involved in getting robots to interact in the real world.

      But in this case, I can't get this [] out of my head.

  • by sgt scrub ( 869860 ) <saintium@ y a h o o .com> on Friday September 23, 2011 @02:38PM (#37494696)

    They used linear algebra to teach neural nets to do linear algebra? My brain hurts.

  • I suggest this is the start to the long road described in the short story "The Feeling of Power" by Isaac Asimov. In the future someone will re-invent the art of human computation, and manned missiles (and thus human computing of trajectories) will follow.

  • This algorithm might be more optimal but is also slower than the alternatives. Electricity is cheap, time is not.

You are in a maze of little twisting passages, all different.