Multiple Turtlebots in Gazebo

edit

Hi. I am also working with 2 Turtlebots in Gazebo (ROS Fuerte). I was able to separate both /cmd_vel and /odom topics. Here is what I did:

Go to gazebo_ros_create.h and add a new private variable:

std::string robot_namespace_;

Go to gazebo_ros_create.cpp. Add the following lines in the function GazeboRosCreate::Load (I added it around line 56)

this->robot_namespace_ = "";
if (_sdf->HasElement("robotNamespace")) { 
  this->robot_namespace_ = _sdf->GetElement("robotNamespace")->GetValueString() + "/";
}

With that line you are getting the namespace you assigned for the nodes (in my case turtle_1 and turtle_2). Modify the line corresponding to node_namespace in order to add the robotNamespace String on it:

this->node_namespace_ = "";
if (_sdf->HasElement("node_namespace")) {
  this->node_namespace_ = this->robot_namespace_ + _sdf->GetElement("node_namespace")->GetValueString() + "/";
}

Now go down and find the lines in which you subscribe/advertise the topics /cmd_vel, /odom and /sensor_state and change them to local names cmd_vel, odom and sensor_state. The lines should now look like this:

cmd_vel_sub_ = rosnode_->subscribe("cmd_vel", 1, &GazeboRosCreate::OnCmdVel, this );

sensor_state_pub_ = rosnode_->advertise<turtlebot_node::TurtlebotSensorState>("sensor_state", 1);
odom_pub_ = rosnode_->advertise<nav_msgs::Odometry>("odom", 1);
joint_state_pub_ = rosnode_->advertise<sensor_msgs::JointState>("joint_states", 1);

Finally, rosmake the package (make sure that you generate a new library, erase the ROS_NOBUILD if needed (otherwise the library won't be compiled and your changes won't be effective)

Hope it helps. If you found other way to work around this (other than editing the source code), please let me know.

Thanks!

Ana

Hello,

I tried to follow this instructions but I was not able to deploy two turblebots: I see just one /odom and /cmd_vel topic. Besides the modification to the aforementioned gazebo_ros_create.cpp I use to launch file for the two turtlebots, here I just report one, the second differs just by the namespace.

Thank you

<launch>
<group ns="SCORZIE">
  <param name="robot_description" command="$(find xacro)/xacro.py '$(find turtlebot_description)/urdf/turtlebot.urdf.xacro'"/>
</group>
  <node name="spawn_turtlebot_model" pkg="gazebo" type="spawn_model" args="$(optenv ROBOT_INITIAL_POSE) -unpause -urdf -param robot_description -x 9 -y 5 -z 0.05 -model turtlebot1" respawn="false" output="screen" ns="SCORZIE"/>

  <node pkg="diagnostic_aggregator" type="aggregator_node" name="diagnostic_aggregator" ns="SCORZIE" >
    <rosparam command="load" file="$(find turtlebot_bringup)/config/diagnostics.yaml" />
  </node>

  <node pkg="robot_state_publisher" type="state_publisher" name="robot_state_publisher" output="screen" ns="SCORZIE">
    <param name="publish_frequency" type="double" value="20.0" />
  </node>


  <!-- The odometry estimator -->

  <node pkg="robot_pose_ekf" type="robot_pose_ekf" name="robot_pose_ekf" ns="SCORZIE">
    <param name="freq" value="30.0"/>
    <param name="sensor_timeout" value="1.0"/>
    <param name="publish_tf" value="true"/>
    <param name="odom_used" value="true"/>
    <param name="imu_used" value="false"/>
    <param name="vo_used" value="false"/>
    <param name="output_frame" value="odom"/>
    <param name="output_frame" value="odom" />
  </node>


  <!-- throttling -->
  <node pkg="nodelet" type="nodelet" name="pointcloud_throttle" args="load pointcloud_to_laserscan/CloudThrottle openni_manager" respawn="true" ns="SCORZIE">
    <param name="max_rate" value="20.0"/>
    <remap from="cloud_in" to="/camera/depth/points"/>
    <remap from="cloud_out" to="cloud_throttled"/>
  </node>

  <!-- Fake Laser -->
  <node pkg="nodelet" type="nodelet" name="kinect_laser" args="load pointcloud_to_laserscan/CloudToScan openni_manager" respawn="true" ns="SCORZIE">
    <param name="output_frame_id" value="/camera_depth_frame"/>
    <!-- heights are in the (optical?) frame of the kinect -->
    <param name="min_height" value="-0.15"/>
    <param name="max_height" value="0.15"/>
    <remap from="cloud" to="/cloud_throttled"/>
  </node>

  <!-- Fake Laser (narrow one, for localization -->
  <node pkg="nodelet" type="nodelet" name="kinect_laser_narrow" args="load pointcloud_to_laserscan/CloudToScan openni_manager" respawn="true" ns="SCORZIE">
    <param name="output_frame_id" value="/camera_depth_frame"/>
    <!-- heights are in the (optical?) frame of the kinect -->
    <param name="min_height" value="-0.025"/>
    <param name="max_height" value="0.025"/>
    <remap from="cloud" to="/cloud_throttled"/>
    <remap from="scan" to="/narrow_scan"/>
  </node>


</launch>