[BREAKING CHANGE] Use robot_description topic instead of ~/robot_description and update docs regarding this

controller_manager/doc/userdoc.rst

@@ -70,10 +70,6 @@ hardware_components_initial_state.unconfigured (optional; list<string>; default:
 hardware_components_initial_state.inactive (optional; list<string>; default: empty)
   Defines which hardware components will be configured immediately when controller manager is started.
 
-robot_description (mandatory; string)
-  String with the URDF string as robot description.
-  This is usually result of the parsed description files by ``xacro`` command.
-
 update_rate (mandatory; integer)
   The frequency of controller manager's real-time update loop.
   This loop reads states from hardware, updates controller and writes commands to hardware.
@@ -83,6 +79,58 @@ update_rate (mandatory; integer)
   Name of a plugin exported using ``pluginlib`` for a controller.
   This is a class from which controller's instance with name "``controller_name``" is created.
 
+Subscribers
+-----------
+
+robot_description (std_msgs/msg/String)
+  The URDF string as robot description.
+  This is usually published by the ``robot_state_publisher`` node.
+
+Handling Multiple Controller Managers
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+When dealing with multiple controller managers, you can manage different robot descriptions either
+using remappings or putting both, the ``robot_state_publisher`` and the ``controller_manager`` into
+the same namespace.
+
+Using namespaces a snippet of a launchfile could look like the following:
+
+.. code-block:: python
+
+   control_node = Node(
+       package="controller_manager",
+       executable="ros2_control_node",
+       parameters=[robot_controllers],
+       output="both",
+       namespace="rrbot",
+   )
+   robot_state_pub_node = Node(
+       package="robot_state_publisher",
+       executable="robot_state_publisher",
+       output="both",
+       parameters=[robot_description],
+       namespace="rrbot",
+   )
+
+
+Using remappings:
+
+.. code-block:: python
+
+   control_node = Node(
+       package="controller_manager",
+
+       parameters=[robot_controllers],
+       output="both",
+       remappings=[('robot_description', '/rrbot/robot_description')]
+   )
+   robot_state_pub_node = Node(
+       package="robot_state_publisher",
+       executable="robot_state_publisher",
+       output="both",
+       parameters=[robot_description],
+       namespace="rrbot",
+   )
 
 Helper scripts
 --------------

controller_manager/src/controller_manager.cpp

@@ -284,7 +284,7 @@ ControllerManager::ControllerManager(
     RCLCPP_WARN(
       get_logger(),
       "[Deprecated] Passing the robot description parameter directly to the control_manager node "
-      "is deprecated. Use '~/robot_description' topic from 'robot_state_publisher' instead.");
+      "is deprecated. Use the 'robot_description' topic from 'robot_state_publisher' instead.");
     init_resource_manager(robot_description_);
     init_services();
   }
@@ -329,7 +329,7 @@ void ControllerManager::subscribe_to_robot_description_topic()
   // set QoS to transient local to get messages that have already been published
   // (if robot state publisher starts before controller manager)
   robot_description_subscription_ = create_subscription<std_msgs::msg::String>(
-    "~/robot_description", rclcpp::QoS(1).transient_local(),
+    "robot_description", rclcpp::QoS(1).transient_local(),
     std::bind(&ControllerManager::robot_description_callback, this, std::placeholders::_1));
   RCLCPP_INFO(
     get_logger(), "Subscribing to '%s' topic for robot description.",