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Re: [SeattleRobotics] Re: Steampunk Mouse

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  • Peter Balch
    ... Guilty as charged. But the sort of craftwork needed to make steampunk nonsense requires much less intellectual effort. It s just relaxation. Given the huge
    Message 1 of 135 , Apr 6 2:16 PM
      > From: dan michaels
      > While I have been
      > hard at work on Poco, my quadruped, you've been bored and avoiding
      > working on your own quad.

      Guilty as charged. But the sort of craftwork needed to make steampunk
      nonsense requires much less intellectual effort. It's just relaxation.

      Given the huge interest, I ought to start making a bunch of them right away.
      I thought I could source everything but I was mistaken about the "gallery
      rail" (the brass fretwork).

      Any ideas where it can be bought?

      Peter
    • David Buckley
      ... But the whole point of LOT is that the catcher doesn t move in a straight line. Fig 2 Ball Catching: An Example of Psychologically-based Behavioural
      Message 135 of 135 , Apr 15 5:15 PM
        > If you're moving in a straight line, and the ball is at a
        But the whole point of LOT is that the catcher doesn't move in a straight line.
        Fig 2
        Ball Catching:  An  Example of Psychologically-based Behavioural Animation
        M  F  P  Gillies  and N A  Dodgson
        Cambridge  University  Computer  Laboratory
        February  3,  1999
        and the (shaggy) dog story
        bhattacharjee nyt 1-7-03 fly ball or frisbee.pdf
         
        I think one of the problems is they are working from 2d images from one camera  (with no depth information so projection is no big deal) whereas animals work from 3d and our depth perception is very fine even at distances where they say we can't judge depth (they are probably doing sums again).
         
        DAvid
         
        ----- Original Message -----
        Sent: Friday, April 15, 2011 11:57 PM
        Subject: RE: [SeattleRobotics] dream bots ... [was: Re: Steampunk Mouse

         

        David Buckley said: Friday, April 15, 2011 5:00 PM
        > they certainly are not doing sums

        I still hold they are using a special solution to a differential
        equations, but can't offer one yet.

        But let me explain my inspiration for suggesting such. Something
        from my Navy days on the ships bridge as a watch officer. As
        Officer of the Deck (second only to the Captain himself for
        operational control of the ship) we were taught to use parallel
        rulers, and a special chart paper, to determine how close
        another ship would pass to us, called CPA (closest point of
        approach) which is very complex due to relative motion of both
        ships through the water. But even the lowliest seaman was taught
        how to tell if we were on a colision course.

        Constant bearing, decreasing range. You're gonna get hit.

        It doesn't matter if two ships are heading toward each other, or
        one toward and one away, or at any odd angle and any odd speed.
        If you see constant bearing, decreasing range, courses and
        speeds remain constant, collision is going to happen.

        Here, with relative motion of ships, the problem is simpler than
        the baseball, because the action is all in 2D, without the third
        vertical dimension with gravity's acceleration component. Non
        the less, all the complexities of the algebraic solution
        disappear and the constant bearing, decreasing range, the result
        is certain. I think the principle is the same for the 3D case.

        If you're moving in a straight line, and the ball is at a
        constant relative bearing, you're going to intercept it's line
        of motion. This doesn't explain how you know if you'll be where
        you can reach it, whether it will be above your head, or already
        rolling on the ground, but your lines of motion will intersect
        for sure.

        So there's part of the key. What line to choose so it is the
        right height is the other part. How that is done, I don't know.
        But once you know that line speed is the only variable, running
        fast enough to keep the relative bearing static will get you
        there.

        Randy

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