I have some questions about fiducial finder.
My robot (robot1) must recognize  another robot (robot2) and then take its distance. So i think fiducial would be useful for my necessity. This is a part of  statement for robot2 in my world file:

  <id> robot2 </id>
  <fiducial> 100 </fiducial>

but it doesn't work: robot1 can't detect robot2 using fiducial.
First question is: can i use fiducial for detecting robots ? or i can use it for only detect SimpleSolid in the world ?
I use fiducial also for detect SimpleSolid. I have noted a correlation between size of objects that must be detected and the robot's ability to detect them using fiducial:  bigger is  their size, farther robot can detect them. is it correct ?
Since my robot must decect little object How i can increase robot's sensibility to detect these objects ?

Thanks in advance