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Modify environment

Overview

This tutorial will explain how to modify the simulated Atlas's environment, such as adding objects to the world.

  1. Create a new ROS package based on the DRC simulation package.
  2. Copy launch files and world from the DRC simulation package, and edit them to reference each other.
  3. Create a custom world file with extra objects.
  4. Launch the new simulation with a ROS command.

Setup

We assume that you've already done the installation step.

If you haven't done so, add the environment setup.sh files to your .bashrc.

echo 'source /usr/share/drcsim/setup.sh' >> ~/.bashrc
source ~/.bashrc

If you haven't already, create a ros directory in your home directory and add it to your $ROS_PACKAGE_PATH. From the command line

mkdir -p ~/ros
echo "export ROS_PACKAGE_PATH=${HOME}/ros:${ROS_PACKAGE_PATH}" >> ~/.bashrc
source ~/.bashrc

Use roscreate-pkg to create a ROS package for this tutorial, depending on drcsim_gazebo:

cd ~/ros
roscreate-pkg world_modification_tutorial drcsim_gazebo

The code

The DRC Simulator includes a simulation environment that puts the Atlas Robot in an empty world. You can launch this simulation configuration like so:

roslaunch drcsim_gazebo atlas.launch

For drcsim < 3.1.0: The package and launch file had a different name:

roslaunch atlas_utils atlas.launch

You'll see the robot on its own, with just the ground:

Press Control-C in the terminal where you executed the roslaunch command (not in the GUI) to kill the simulator.

We want to add some objects to that world. But we don't want to modify the contents of drcsim_gazebo, because it is a system-installed package. Instead, we'll use our ROS package created above in the Setup step and copy some files into it:

roscd world_modification_tutorial

The above command is equivalent to: cd ~/ros/world_modification_tutorial

mkdir worlds launch

roscd drcsim_gazebo

The above command takes you to the drcsim_gazebo directory, which may be different according to your installation. It will be something like /opt/ros/indigo/share/drcsim_gazebo. We will copy some files from there:

cp launch/atlas.launch ~/ros/world_modification_tutorial/launch/
cp launch/atlas_no_controllers.launch ~/ros/world_modification_tutorial/launch/
cp ../drcsim_model_resources/worlds/atlas.world ~/ros/world_modification_tutorial/worlds/

roscd world_modification_tutorial/

Now that we have our own copies of the .launch and .world files, we can make changes. We'll start with the .launch files: open ~/ros/world_modification_tutorial/launch/atlas.launch in a text editor.

gedit ~/ros/world_modification_tutorial/launch/atlas.launch

  1. Look for this line:

    <include file="$(find drcsim_gazebo)/launch/atlas_no_controllers.launch">

  2. In this atlas.launch file, which is our local copy, we want to use our local copy of the atlas_no_controllers.launch file. So replace the above line with:

    <include file="$(find world_modification_tutorial)/launch/atlas_no_controllers.launch">

Now we need to change atlas_no_controllers.launch to refer to the correct world file.

gedit ~/ros/world_modification_tutorial/launch/atlas_no_controllers.launch

  1. Look for this line:

    <node name="gazebo" pkg="drcsim_gazebo" type="run_$(arg gzname)" args="$(arg gzworld) $(arg extra_gazebo_args)" output="screen" />

  2. Again, to use local copies, we replace the above line with:

    <node name="gazebo" pkg="drcsim_gazebo" type="run_$(arg gzname)" args="$(find world_modification_tutorial)/worlds/$(arg gzworld) $(arg extra_gazebo_args)" output="screen" />

Now you're ready to make modifications to the world. There are a variety of ways to do this; see the building a world tutorial to get started. For now, we'll make some simple edits via the simulator GUI. Launch the Simulator using your just-edited atlas.launch file:

roslaunch world_modification_tutorial atlas.launch

You should see the same environment: Atlas in an empty world. Make some changes:

  1. Add a box. In the toolbar, click on the box/cube icon to insert a box in the world. Move the mouse to where you want it and click to drop it.
  2. Add a sphere. Same as for the box, except click on the sphere icon to start.
  3. Add a cylinder. Same as for the others, except click on the cylinder icon to start.

You should see something like this:

Now you can save your changes: in the Gazebo GUI, click "File->Save World As". When prompted for where to save it, browse to world_modification_tutorial/worlds/atlas.world to overwrite our copy of Atlas's simulation world.

Now, modify the world file to remove the Atlas model. This is because the robot is spawned automatically.

gedit ~/ros/world_modification_tutorial/worlds/atlas.world

Look for the <model name='atlas'> tag and remove it entirely (until the next '' tag few hundred lines of text).

Note: Currently, loading a world that contains <state> tags is not working properly. Thus, you must also delete the <state> tag and all its child elements (everything from <state> until </state>).

Now, if you haven't done so already, stop the simulation (via Ctrl+C in the terminal where you ran roslaunch), and start it again:

roslaunch world_modification_tutorial atlas.launch

You should see the modified world, as it was when you saved it.

From here, you're ready to modify the robot's environment any way you like. Have a look at SDF documentation and edit ~/ros/world_modification_tutorial/worlds/atlas.world however you like.