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Thread: Extendable arm?

  1. #1 Extendable arm? 
    New Member
    Join Date
    Sep 2009
    Hi folks,

    We have a design project in a freshmen engineering class that is appearing to be quite a challenge. The setting is a stairwell with five 1-ft high steps with a 1-lb weight positioned on each individual step. Our task is to create a battery powered device that can move each of those 1-lb weights to the top step of the stairwell autonomously - no RC allowed.

    We haven't completely settled on which path we're going to take with it. We're being steered by constraints toward making the device a stair-climbing robot, but i'm trying to avoid that since I feel it would be the most difficult to make effective. I personally liked the idea of a setup similar to a gantry crane that would use an electromagnet to pick up each of the weights and carry them to the top. Problem is the constraints: the device can initially only be 1-ft tall (the size of a single step) and must start on the floor - it cannot touch any of the steps or the surrounding area. That throws a wrench in that idea, unless we were to use some method to extend the device vertically and horizontally after it is initially turned on.

    Before we chuck the crane idea, I was wondering if anyone here had some general suggestions on mechanisms to make the device extendable. To make it work, we would need the device to be extendable both horizontally (6ft) and vertically (6ft), while being strong enough to be able to support the 1lb weights. Seems like a daunting task...

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  3. #2  
    Forum Freshman Solveer's Avatar
    Join Date
    Dec 2009
    Freshman class, you say? This sounds like the kind of project you would encounter in a junior level class assuming that you will actually end up building the thing...
    Have you considered a caterpilar track that spans two steps at a time (or unfolds to that size)? that way you don't have to worry about there being steps at all. Assuming all weights are placed in-line you could have two tracks that are wider than the weights and so you would only have to deal with a go-up/go-down algorithm plus anything required to pick up/drop off the weights.
    I recommend you stay away from expanding gantries and cranes. That sounds too complicated.

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  4. #3  
    Time Lord
    Join Date
    Apr 2008
    This sounds like a puzzle where the best solution involves using one weight/volume to move another. Like those peg rearranging games, or the Tower of Hanoi.
    A pong by any other name is still a pong. -williampinn
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