ros parametor angle_min&angle_max are not valid

[nnn112358]

I tried using with reference to "urg_lidar.launch", and it seems that angle_min and angle_max are not effective.

<launch>
  <node name="urg_node" pkg="urg_node" type="urg_node" output="screen">
    <param name="angle_min" value="-1.5707963"/>
    <param name="angle_max" value="1.5707963"/>
  </node>
</launch>

Looking at urg_node_driver.cpp , there are no ros parametor, angle_min" and "angle_max", in pnh_.param.