Embedded Motion Control 2013/Simulator

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If you followed all steps specified on the installation page , you will already have downloaded the simulator Gazebo and our specific Jazz simulator. To be able to use the Jazz simulator, you first have to compile the downloaded ROS packages:

  1. Open a terminal (ctrl-alt-t)
  2. Make sure rosdep is initialized and up to date:
    sudo rosdep init
    rosdep update
  3. Build and compile the jazz simulator and other necessary packages:
    rosmake jazz_gazebo gazebo_map_spawner

Furthermore, Gazebo needs to know where to find the robot description (located in jazz_description) which includes its meshes, textures, kinematic chain, etc, and where to find the plugins for the controllers and sensors. This information can be set in the environment variables GAZEBO_PLUGIN_PATH and GAZEBO_MODEL_PATH:

  1. Open a terminal (ctrl-alt-t)
  2. Open .bashrc:
    gedit ~/.bashrc
  3. Add the following lines:
    export GAZEBO_PLUGIN_PATH=~/ros/emc/general/jazz_gazebo/lib:~/ros/emc/general/tue_gazebo_plugins/lib:$GAZEBO_PLUGIN_PATH
    export GAZEBO_MODEL_PATH=~/ros/emc/general/jazz_description:$GAZEBO_MODEL_PATH
  4. and source your .bashrc:
    source ~/.bashrc
    or start a new terminal.

Starting the Simulator

  1. Start Gazebo:
  2. Start another terminal and spawn the maze:
    rosrun gazebo_map_spawner spawn_maze
  3. Spawn PICO:
    roslaunch pico_gazebo pico.launch

Notice that the Jazz robot is spawned in the Gazebo world. The Gazebo GUI shows how the world actually is. We can also visualize how the robot perceives it through its sensors, by using the ROS tool Rviz. You can start RViz with a pre-defined config showing most of Jazz' sensors using:

rosrun jazz_visualization rviz

In fact, this simply runs the following command:

rosrun rviz rviz -d ~/ros/general/jazz_visualization/rviz/jazz.vcg

If you are running the Gazebo simulation, you will see the Jazz robot model and white dots which represent the sensor data originating from the (simulated) laser range finder. RViz allows you to visualize many more things. For example, to show the data from the camera:

  1. Click on the Add button in the lower left
  2. Select Camera and click OK. A Camera item will pop up in the Displays view on the left.
  3. Click in the field right next to Image Topic and click the ... button. Now you can select the camera topic (/pico/camera/image)

You will see the camera images visualized in the lower left of your screen.


Here are some examples on how to use the simulator and how to practice the corridor competition in simulation.

Jazz Driving Example

  1. Have a look at the file jazz_node.cpp in the src folder of the jazz_example package. You should be able to understand what the program will do.
  2. Build the package:
    rosmake jazz_example
  3. Run the node (make sure the simulator is still running):
    rosrun jazz_example jazz_node
    Check the result in both Gazebo and RViz.
  4. Feel free to use this example as a start for your project

Jazz Safe Driving Example

  1. First of all, make sure you have the latest version of the jazz_example package:
    1. roscd jazz_example
    2. svn up
  2. Take some time to have a good look at the file safe_drive.cpp in the src folder of the jazz_example package. It contains a quite elaborate explanation of what is going on in the code, which will hopefully clarify quite some things.
  3. Build the package:
    rosmake jazz_example
  4. Run the node (make sure the simulator is still running):
    rosrun jazz_example safe_drive
    Check the result in both Gazebo and RViz.
  5. Feel free to use this example as a start for your project


Gazebo does not stop gracefully upon exit or interrupt (ctrl-c)

You may get the warning:

Warning [gazebo_main.cc:59] escalating to SIGKILL on server

when stopping Gazebo. This is a known bug and has no consequences, other than that it takes a bit longer to kill Gazebo.