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How to control heavy ball in x and y direction?

  1. Jul 28, 2012 #1
    Hi there - I'm trying to build a decorational device that holds a rather heavy ball and I want to be able to control it's "movement/roll" in the X and Y directions (they are horizontal as well as orthogonal).


    The two black cylinders (X and Y) aren't floating, but I forgot to draw their support pillars. They are wrapped into a rubber band each, which both are attached to two differrent motors in order to make them rotate.

    The support is just an attempt to not drop the ball and is placed "behind" it from our point of view.

    I have 2 questions:

    1) If only the X-motor runs, will there be such a great friction between the ball and the Y-rubber that this configuration won't work?

    2) Do you have any other ideas where the motion will come from external motors and rubber bans?
  2. jcsd
  3. Jul 28, 2012 #2


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    Welcome to PF, Patrick.
    Your questions confuse me a bit, and I'm no expert in the matter anyhow, but I have one suggestion which might be an answer to #1. If you place your rollers farther out around the circumference of the ball, you will lower its centre of gravity and thus make the system more stable.
  4. Jul 28, 2012 #3


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    Hard to say but in principle, yes. There is definitely a lot of friction here.

    Your device is identical to the computer mouse with a ball configuration. Two rollers at 90 degrees with a 3rd for support. However, yours is upside down from a mouse. That means all the weight of your ball rests on the rollers. With a heavy ball and rubber rollers, you will definitely have a lot of problems with friction.

  5. Jul 29, 2012 #4
    Would something like this work?

  6. Jul 30, 2012 #5


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