Hi all, now i simulated the mecanum wheels in gazebo by simulate one hub and 12 free moving rollers, it's working but when go to the side move(side left, side right), the performance was not good, it move slowly and shake to left and right direction, i assumed that it is because of friction between plane and rollers, but i changed the <mu1>1</mu1> <mu2>1</mu2> of each rollers , it does not work.. Can someone give me some suggestions about how to fix that? Thanks in advance! Shengnan Chen