sousarbarb / urdf_sim_tutorial

urdf_sim_tutorial

Nonfunctional gazebo interface

roslaunch urdf_sim_tutorial gazebo.launch

Gazebo plugin

1. Link Gazebo and ROS
   • See 09-publishjoints.urdf.xacro file

  <gazebo>
    <plugin name="gazebo_ros_control" filename="libgazebo_ros_control.so">
      <robotNamespace>/</robotNamespace>
    </plugin>
  </gazebo>

2. Test the model that links ROS and Gazebo
   • Does not do anything. It is required more information!

roslaunch urdf_sim_tutorial gazebo.launch model:=`rospack find urdf_sim_tutorial`/urdf/09-publishjoints.urdf.xacro

3. Spawning controllers
   • Kind off bits of ROS code to run within Gazebo
   • Specified in the file joints.yaml
4. Test the spawner script that loads the controller and publishes the state of the robot's joints into ROS directly from Gazebo
   • If you execute rostopic list, you can see that /joint_states topic is publishing but with nothing in it

roslaunch urdf_sim_tutorial 09-joints.launch

5. Transmissions
   • For every non-fixedd joint, it is necessary to specify a transmission to tell Gazebo that to do with the joint!
   • See tags <transmission> in the urdf file (including for the wheels)
6. Joint control
   • Specify a joint controller for each joint
   • See the yaml files in config

Drive the Droid

roslaunch urdf_sim_tutorial 13-diffdrive.launch

Useful links to learn more about Gazebo and URDF/Xacro

• Introduction to Xacro and URDF: https://ni.www.techfak.uni-bielefeld. de/files/URDF-XACRO.pdf
• Tutorial URDF: http://wiki.ros.org/urdf/Tutorials
  • Using URDF in Gazebo: http://wiki.ros.org/urdf/Tutorials/Using%20a%20URDF%20in%20Gazebo
  • GitHub: https://github.com/ros/urdf_sim_tutorial/blob/master/config/diffdrive.yaml
  • Gazebo: http://gazebosim.org/tutorials/?tut=ros_urdf