field of view of sonar sensor

Hi,
In your sonar launch you use the sonar.xacro where is parameter _**field_of_view="56"**_, it is seems that you use it as degree in sonar_model.xacro (<min_angle>-${**field_of_view** / 2}</min_angle> but it should be in radians see http://wiki.ros.org/urdf/XML/sensor.

> min_angle (optional: default 0) (float) (radians)