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Subject: 
Re: The Great Ball Contraption
Newsgroups: 
lugnet.robotics
Date: 
Sun, 9 Jan 2005 22:09:09 GMT
Viewed: 
8783 times
  
In lugnet.robotics, Russell Nelson <nelson@crynwr.com> wrote:
> Steve Baker writes:
> > Another thought I had was that the organisers might want to consider
> > building a stage that has one input hopper and TWO outputs that sends
> > balls alternately to the two places.
> 
> Yes!  Since the soccer and basket balls are the same physical size,
> there is no reason why a module can't work with both.  There is also
> no reason why a module couldn't sort soccer balls out one side, and
> basketballs out another.
> 
> To that end, you need a specification for a "Y" module, which has two
> output faces.  Also for a module which has two input faces!  And a
> module which is a 90-turning corner and a 270-turning corner.  It's
> pretty obvious what's needed for them; it just needs to be written down.

I made a device that sends balls alternately down two chutes.

Balls enter through a 2x2 hole in the top, onto the centre of a 7L studless
beam, set up as a see-saw.

Which ever way a ball goes, it drops onto another, longer, see-saw that tilts
the first see-saw the other way to send the next ball down the other chute.
Balls exit though 2x2 holes in the bottom at each side.

I used two more studless beams (liftarms work well too) crossed over to do the
reversing links between the see-saws.

This contraption is about 13 bricks high and 4L deep, but could be made smaller
in height.  Its advantage it that it doesn't need a motor.  The minimum height
is dictated by the need for the energy from a ball dropping nto the lower
see-saw being more than enough to tilt both see-saws.

Of course this device won't sort balls by colour, but that's a slow process.
Also, soccer balls have black and white bits so you can't predict which bit a
light sensor will see, and hence whether the reading from a soccer ball will be
greater or less than the reading from a basketball.

I used the see-saw device with a vertical ball lifter, based on transmission
chain with a few track links.  It was possible to over-run the see-saw device
with too many balls, so that two went the same way, but the through-put had to
be quite fast before that happened.

A module with 2 input faces would probably be a hopper with 2 chutes entering
it.  The greatest problem I've had with ball contraptions is balls clogging in
the hopper - sometimes you need an agitator like they use in factories.

Mark



Message has 1 Reply:
  Re: TGBC - The Weakest Link?
 
(...) Any operation involving a long sequence of events as in The Great Ball Contraption (TGBC) is likely to be fouled up by failure of one of the events in the chain - the so called weakest link. Is there allowance for the fact that one of the (...) (22 years ago, 9-Jan-05, to lugnet.robotics)

Message is in Reply To:
  Re: The Great Ball Contraption
 
Steve Baker writes: > Another thought I had was that the organisers might want to consider > building a stage that has one input hopper and TWO outputs that sends > balls alternately to the two places. Yes! Since the soccer and basket balls are the (...) (22 years ago, 9-Jan-05, to lugnet.robotics)

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