How to control heavy ball in x and y direction?

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Discussion Overview

The discussion revolves around controlling the movement of a heavy ball in both the X and Y directions using motors and rubber bands. Participants explore the feasibility of the proposed design and suggest alternative approaches for achieving the desired motion.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant questions whether running only the X-motor would create excessive friction between the ball and the Y-rubber, potentially hindering movement.
  • Another participant suggests that placing the rollers farther out around the circumference of the ball could lower its center of gravity, potentially increasing stability.
  • A different participant compares the device to a computer mouse with a ball configuration, noting that the weight of the ball resting on the rollers could lead to significant friction issues.
  • One participant proposes a concept similar to a floating granite ball fountain, suggesting the use of motorized wheels to achieve movement in the desired directions.

Areas of Agreement / Disagreement

Participants express uncertainty regarding the frictional effects of the proposed design, with no consensus on whether the configuration will work as intended. Multiple competing ideas for alternative approaches are also presented.

Contextual Notes

Participants have not fully explored the implications of the weight distribution and the specific materials used in the design, leaving some assumptions unaddressed.

Who May Find This Useful

Individuals interested in mechanical design, robotics, or those exploring innovative methods for controlling movement in physical systems may find this discussion relevant.

_Patrick_
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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).

2w1wp3l.jpg


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?
 
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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.
 
_Patrick_ said:
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?

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.

Mouse-mechanism-cutaway.png
 
Would something like this work?

rotating+globe.jpg
 
You could do something similar to a floating granite ball fountain, but with motorized wheels to spin it in the needed directions.

http://www.hydrodramatics.com/floating_granite_ball_fountains.htm
floating_granite_ball.jpg
 

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