Updated xacro material

urdf/lidar_lite.xacro

@@ -16,7 +16,9 @@
         <geometry>
           <mesh filename="package://iri_lidar_lite_description/meshes/${resolution}_lidar_lite.stl" />
         </geometry>
-        <material name="Black" />
+        <material name="DarkGrey">
+          <color rgba="0.2 0.2 0.2 1.0"/>
+        </material>
       </visual>
       <collision>
         <origin xyz="0 0 0" rpy="0 0 0"/>