ros: launch files for offboard postion setpoints demo

launch/gazebo_ardrone_empty_world_offboard_demo.launch

+
+<launch>
+
+<include file="$(find px4)/launch/gazebo_ardrone_empty_world.launch" />
+<include file="$(find px4)/launch/mavros_sitl.launch" />
+<group ns="px4_multicopter">
+	<node pkg="px4" name="demo_offboard_position_setpoints" type="demo_offboard_position_setpoints"/>
+</group>
+
+</launch>

launch/mavros_sitl.launch

@@ -2,18 +2,20 @@
 	<!-- vim: set ft=xml noet : -->
 	<!-- example launch script for PX4 based FCU's -->
 
-	<arg name="fcu_url" default="udp://localhost:14560@localhost:14565" />
-	<arg name="gcs_url" default="" />
-	<arg name="tgt_system" default="1" />
-	<arg name="tgt_component" default="50" />
+	<group ns="px4_multicopter">
+		<arg name="fcu_url" default="udp://localhost:14560@localhost:14565" />
+		<arg name="gcs_url" default="" />
+		<arg name="tgt_system" default="1" />
+		<arg name="tgt_component" default="50" />
 
-	<include file="$(find mavros)/launch/node.launch">
-		<arg name="blacklist_yaml" value="$(find mavros)/launch/px4_blacklist.yaml" />
-		<arg name="config_yaml" value="$(find mavros)/launch/px4_config.yaml" />
+		<include file="$(find mavros)/launch/node.launch">
+			<arg name="blacklist_yaml" value="$(find mavros)/launch/px4_blacklist.yaml" />
+			<arg name="config_yaml" value="$(find mavros)/launch/px4_config.yaml" />
 
-		<arg name="fcu_url" value="$(arg fcu_url)" />
-		<arg name="gcs_url" value="$(arg gcs_url)" />
-		<arg name="tgt_system" value="$(arg tgt_system)" />
-		<arg name="tgt_component" value="$(arg tgt_component)" />
-	</include>
+			<arg name="fcu_url" value="$(arg fcu_url)" />
+			<arg name="gcs_url" value="$(arg gcs_url)" />
+			<arg name="tgt_system" value="$(arg tgt_system)" />
+			<arg name="tgt_component" value="$(arg tgt_component)" />
+		</include>
+	</group>
 </launch>