Allow starting the Gazebo robot w/ and w/o a namespace.

By default, we don't start in a namespace to match the real-robot behavior.
Unfortunately, we cannot just specify an empty ns="" in roslaunch, but we
need to distinguish the two cases empty/non-empty namespace.
To avoid code duplication, the relevant code was factored out into panda_ns.launch.xml,
which is include w/ or w/o a namespace.
The file-ending is deliberatively choosen as .launch.xml to hide the file from bash completion.

franka_gazebo/launch/panda.launch

@@ -1,5 +1,6 @@
 <?xml version="1.0"?>
 <launch>
+  <arg name="ns" default="" doc="Namespace to launch the Gazebo robot in" />
 
   <!-- Gazebo & GUI Configuration -->
   <arg name="gazebo"      default="true"  doc="Should the gazebo simulation be launched? Use false in case if you want to include this file and launch gazebo yourself" />
@@ -37,65 +38,10 @@
     <arg name="use_sim_time" value="true"/>
   </include>
 
-  <group ns="$(arg arm_id)">
-    <param name="robot_description"
-           command="xacro $(find franka_description)/robots/panda_arm.urdf.xacro
-                    gazebo:=true
-                    hand:=$(arg use_gripper)
-                    arm_id:=$(arg arm_id)
-                    ns:=$(arg arm_id)
-                    xyz:='$(arg x) $(arg y) $(arg z)'
-                    rpy:='$(arg roll) $(arg pitch) $(arg yaw)'">
-    </param>
 
-    <rosparam file="$(find franka_gazebo)/config/franka_hw_sim.yaml" subst_value="true" />
-    <rosparam file="$(find franka_gazebo)/config/sim_controllers.yaml" subst_value="true" />
-
-    <arg name="unpause" value="$(eval '' if arg('paused') else '-unpause')" />
-    <node name="$(arg arm_id)_model_spawner"
-          pkg="gazebo_ros"
-          type="spawn_model"
-          args="-param robot_description -urdf -model $(arg arm_id) $(arg unpause)
-                $(arg initial_joint_positions)
-                "/>
-
-    <!-- Spawn required ROS controllers -->
-    <node pkg="controller_manager"
-          type="spawner"
-          name="$(arg arm_id)_gripper_spawner"
-          if="$(arg use_gripper)"
-          args="franka_gripper"
-          respawn="false"
-    />
-
-    <node pkg="controller_manager"
-          type="spawner"
-          name="$(arg arm_id)_controller_spawner"
-          respawn="false" output="screen"
-          args="franka_state_controller $(arg controller)"
-    />
-
-    <node name="robot_state_publisher" pkg="robot_state_publisher" type="robot_state_publisher" />
-    <node name="joint_state_publisher" type="joint_state_publisher" pkg="joint_state_publisher">
-      <rosparam param="source_list">[franka_state_controller/joint_states, franka_gripper/joint_states] </rosparam>
-      <param name="rate" value="30"/>
-    </node>
-    <node name="joint_state_desired_publisher" type="joint_state_publisher" pkg="joint_state_publisher">
-      <rosparam param="source_list">[franka_state_controller/joint_states_desired, franka_gripper/joint_states] </rosparam>
-      <param name="rate" value="30"/>
-      <remap from="joint_states" to="joint_states_desired" />
-    </node>
-
-    <!-- Start only if cartesian_impedance_example_controller -->
-    <node name="interactive_marker"
-          pkg="franka_example_controllers"
-          type="interactive_marker.py"
-          if="$(eval arg('controller') == 'cartesian_impedance_example_controller')">
-      <param name="link_name" value="$(arg arm_id)_link0" />
-      <remap to="cartesian_impedance_example_controller/equilibrium_pose" from="equilibrium_pose" />
-    </node>
-
-  </group>
+  <!-- Depending on whether the namespace is empty or not, don't start in a namespace (or do) -->
+  <include file="$(dirname)/panda_ns.launch.xml" pass_all_args="true" if="$(eval arg('ns') == '')" />
+  <include file="$(dirname)/panda_ns.launch.xml" pass_all_args="true" if="$(eval arg('ns') != '')" ns="$(arg ns)" />
 
   <node  pkg="rviz" type="rviz" output="screen" name="rviz" args="-d $(find franka_gazebo)/config/franka_sim_description_with_marker.rviz" if="$(arg rviz)"/>
 

franka_gazebo/launch/panda_ns.launch.xml

@@ -0,0 +1,66 @@
+<?xml version="1.0"?>
+<launch>
+
+    <!-- This is a helper launch file for panda.launch
+         As roslaunch doesn't allow for empty ns arguments and to avoid code duplication,
+         we factored out code here that should run either in or out a namespace.
+         All arguments are simply inherited from the parent launch file.
+    -->
+    <param name="robot_description"
+           command="xacro $(find franka_description)/robots/panda_arm.urdf.xacro
+                    gazebo:=true
+                    hand:=$(arg use_gripper)
+                    arm_id:=$(arg arm_id)
+                    ns:=$(arg ns)
+                    xyz:='$(arg x) $(arg y) $(arg z)'
+                    rpy:='$(arg roll) $(arg pitch) $(arg yaw)'">
+    </param>
+
+    <rosparam file="$(find franka_gazebo)/config/franka_hw_sim.yaml" subst_value="true" />
+    <rosparam file="$(find franka_gazebo)/config/sim_controllers.yaml" subst_value="true" />
+
+    <arg name="unpause" value="$(eval '' if arg('paused') else '-unpause')" />
+    <node name="$(arg arm_id)_model_spawner"
+          pkg="gazebo_ros"
+          type="spawn_model"
+          args="-param robot_description -urdf -model $(arg arm_id) $(arg unpause)
+                $(arg initial_joint_positions)
+                "/>
+
+    <!-- Spawn required ROS controllers -->
+    <node pkg="controller_manager"
+          type="spawner"
+          name="$(arg arm_id)_gripper_spawner"
+          if="$(arg use_gripper)"
+          args="franka_gripper"
+          respawn="false"
+    />
+
+    <node pkg="controller_manager"
+          type="spawner"
+          name="$(arg arm_id)_controller_spawner"
+          respawn="false" output="screen"
+          args="franka_state_controller $(arg controller)"
+    />
+
+    <node name="robot_state_publisher" pkg="robot_state_publisher" type="robot_state_publisher" />
+    <node name="joint_state_publisher" type="joint_state_publisher" pkg="joint_state_publisher">
+      <rosparam param="source_list">[franka_state_controller/joint_states, franka_gripper/joint_states] </rosparam>
+      <param name="rate" value="30"/>
+    </node>
+    <node name="joint_state_desired_publisher" type="joint_state_publisher" pkg="joint_state_publisher">
+      <rosparam param="source_list">[franka_state_controller/joint_states_desired, franka_gripper/joint_states] </rosparam>
+      <param name="rate" value="30"/>
+      <remap from="joint_states" to="joint_states_desired" />
+    </node>
+
+    <!-- Start only if cartesian_impedance_example_controller -->
+    <node name="interactive_marker"
+          pkg="franka_example_controllers"
+          type="interactive_marker.py"
+          if="$(eval arg('controller') == 'cartesian_impedance_example_controller')">
+      <param name="link_name" value="$(arg arm_id)_link0" />
+      <remap to="cartesian_impedance_example_controller/equilibrium_pose" from="equilibrium_pose" />
+    </node>
+
+</launch>