Hi! I'm using amcl on real pioneer 3dx and laser sicklms200. I have some questions.

1) If I specify correct robot's initial pose,  amcl works very well but if I specify  nothing about robot's initial pose or I specify an initial pose with large uncertain, amcl doesn't converge at right robot's pose.
Is it necessary to specify the right robot's position ?

2)  I have noted on playernav that particles are grouped in "circle" only around the robot and not on the whole map even if the robot's position estimate is wrong.  Is there a way to enlarge  this circle or to spread particles on the whole map?  

3) Can you advise me about the right laser_max_beam and map resolution values ?



Thanks in advance