[robocup-nao] Question about goalie and game stuck

Alexander Buckley albuckley at gmail.com
Fri May 6 15:27:26 EDT 2011

Hi Paul

I wouldn't worry about that paradox. If an opposing teams striker is in your
goalies face, it most likely will be ignoring the collision avoidance output
in that state and continuing to attempt to score. By the sound of what your
saying, I think it is possible you need to address the problem from the
other side, as in, how have you programmed your striker?  If you have that
player set up to always avoid without a dead zone in the controller, it wont
be able to tackle for the ball against other strikers either. Also, if
another striker just walked right at you, it may also be able to back you up
all the way to your own goal if you try and maintain at least a minimum

With most teams playing aggressively close to the ball (not avoiding when
ball is near and obstacle < rangeX) your paradox wont occur. It's within the
rules to have a fair degree of latitude of face to face contact around the
If i was reffing, I might even allow intentional headbutts.

So your keeper is going to have to act in that scenario of yours.


On Fri, May 6, 2011 at 2:13 PM, Paul Schütte <
schuette at informatik.hu-berlin.de> wrote:

> Hi there,
> I have a question regarding the current (2011) rules for RoboCup SPL.
> It is about local game stuck and the goalie. Imagine the following
> situation:
> A goalie in his own penalty area is the closest to the ball (lets say
> distance to ball about 0-5cm but ist not holding the ball!) and an
> opposing attacker is also close to the ball and trying to kick it, but
> since avoiding pushing (or because he is just unable) he can not hit the
> ball. This would be a classical game stuck situation, since the goalie is
> not doing anything but preventing a goal. The question is: who would be
> removed in such a case? Is it the goalie (because beeing closest to the
> ball) or is it the striker because he is impeding other players to see the
> ball and the goalie to do something with the ball? We had a discussion
> about this and came to no general solution on this except to say this is a
> global game stuck. Because removing the goalie would mean that a goal
> would occure (that maybe would not be "as little intervention as possible"
> any more as described in the rules) and removing the field player would be
> against the rules of a local game stuck...
> Any ideas on this? I ask this because it is important for the goalie´s
> behavior: is he allowed to stay in front of the ball being the closest
> player and do "nothing" but preventing passively the ball from getting
> into its own goal?
> Thanks and greetings,
> Paul
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Alexander Buckley
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