[robocup-humanoid] Seven "Size 1" Soccer Balls

[Sean Luke]

On Jun 2, 2015, at 4:38 PM, Luis F Lupián <lupianl at ieee.org> wrote:

> The second and fourth balls from the left seem to be size 0 rather than size 1. When I was shopping around for size 1 balls I realized that some vendors incorrectly offer size 0 balls as if they were size 1.

Hmmm, one of those "size 0" balls is not a fly-by-night ball: it is a Wilson.  I don't think they'd label it size 1 incorrectly.  My googling also doesn't reveal a size 0 :-(.

I have measured the balls in question.  The smallest balls (what you thought might be "size 0") have a circumference3 of 41.5cm.  The medium balls are around 46cm.  The largest ball is 48.5cm.  

Given all this, I suspect that in fact there is no FIFA definition of a "size 1" at all, only a large, vague size range for promotional gifts.  The majority of my size-1 balls hover around 46-48. This jibes with online range suggestions I've seen: but not with the humanoid league specs.

So I think that the specs are probably wrong.  What I want to know is, which of these two parts of the humanoid league spec take precedence at the competition when it comes to disputing the ball sizes used?  

	- "Size 1" -- meaning we could well see at least a 46cm ball
	- "about 13cm in diameter" -- 40.84cm

To help the small size robots, it'd be helpful to know what size ball we should actually be using and what sizes are definitely wrong.

Sean