CODEWITHSUNDEEP
xmlrosroboticslaunch
Ofir
Ofir

Reputation: 771

ROS Remap topic doesn't work - Multiple Robots

Based on the tutorial here, I tried to create my launches to run multiple robots in gazebo. Each robot has a node [called stopper] that takes care to move it. I want that each robot will move separately, so I will publish to {robot_name}/cmd_vel_mux/input/teleop topic.

when running "rostopic info /cmd_vel_mux/input/teleop" I noticed that I have only mobile_base_nodelet_manager as subscriber, with no publisher (the publisher exists into {robot_name}/cmd_vel_mux/input/teleop topic. Therefore, I used remap but it still doesn't work and the same problem appears.

one_robot.lanuch

<?xml version="1.0"?>
<launch> 

   <arg name="robot_name"/>
   <arg name="init_pose"/>

   <node name="spawn_minibot_model" pkg="gazebo_ros" type="spawn_model"
     args="$(arg init_pose) -urdf -param /robot_description -model $(arg robot_name)"
    respawn="false" output="screen" />

    <!-- Launch stopper node -->
    <node name="stopper" pkg="stopper" type="stopper" output="screen" args="$(arg robot_name)">
     <remap from="scan" to="$(arg robot_name)/scan"/>
     <remap from="cmd_vel_mux/input/teleop" to="$(arg robot_name)/cmd_vel_mux/input/teleop"/>

    </node>
</launch>

robots.launch

 <?xml version="1.0"?>
<launch>
  <!-- No namespace here as we will share this description. 
         Access with slash at the beginning -->
  <param name="robot_description"
          command="$(find xacro)/xacro.py $(find turtlebot_description)/robots/kobuki_hexagons_asus_xtion_pro.urdf.xacro"/>

 <!-- BEGIN ROBOT 1-->
 <group ns="robot1">
    <param name="tf_prefix" value="robot1_tf" />
    <include file="$(find stopper)/launch/one_robot.launch" >
      <arg name="init_pose" value="-x 1 -y 1 -z 0" />
      <arg name="robot_name"  value="Robot1" />
    </include>
 </group>

 <!-- BEGIN ROBOT 2-->
 <group ns="robot2">
    <param name="tf_prefix" value="robot2_tf" />
   <include file="$(find stopper)/launch/one_robot.launch" >
     <arg name="init_pose" value="-x -1 -y 1 -z 0" />
     <arg name="robot_name"  value="Robot2" />
   </include>
 </group>
</launch>

multiple_robots.launch

   <?xml version="1.0"?>
   <launch>
      <param name="/use_sim_time" value="true" />

      <!-- include our robots -->
      <include file="$(find stopper)/launch/robots.launch"/>

      <!-- start world -->
      <include file="$(find turtlebot_gazebo)/launch/turtlebot_world.launch"/>       
   </launch>

I would like to get your help to solve this issue, I spent a lot of time on this. Thank you very much!

Upvotes: 0

Views: 4665

Answers (2)

letsbelopez
letsbelopez

Reputation: 1

When you say this, it makes me think remap is working:

when running "rostopic info /cmd_vel_mux/input/teleop" I noticed that I have only mobile_base_nodelet_manager as subscriber, with no publisher (the publisher exists into {robot_name}/cmd_vel_mux/input/teleop topic.

The old topic /cmd_vel_mux/input/teleop doesn't have a publisher anymore, which would be true if remap worked. And you say the publisher exists for the remapped topic, {robot_name}/cmd_vel_mux/input/teleop that means the remap is working.

You say mobile_base_nodelet_manager is subscribing to the old topic, but it should be subscribing to the new topic. Remap doesn't change the topic for both publishers and subscribers. Remap isn't global.

I would make sure the nodes that were subscribing to the old topic, are now subscribing to the new topic. You'll have to do a remap on the Subscribers too, so they know what the new topic is and that they can subscribe to it.

The ROS docs describe remapping on a subscriber node: Remap Docs

Upvotes: 0

Vik
Vik

Reputation: 730

is an option for a given node. Thus I believe it needs to be added under a node tag. So it has to be within the <node> ... </node> block.

Additionally, what you are trying to do could be achieved by launching your teleop nodes under appropriate namespace, either using the <group ns="XXX"> in a launch file or in the terminal by running export ROS_NAMESPACE=XXX before launching the teleop node.

Upvotes: 0

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