adds params

Example yaml file:
<pre>
frame_id: base_footprint

range_min:  1.0
range_max: 10.0

angle_min      : -2.0
angle_max      : 2.0
angle_increment: 0.02

frequency: 10.0

max_reading_age: 4

tolerance: 0.1

scans_in: [left_scan, right_scan]
</pre>