How to set up your workspace

In this tutorial, you will set up a directory on your ROS 2 enabled PC as your workspace for development and install the competition ROS 2 packages. Please follow the instructions below carefully.

Note

This can ONLY be completed after you have set up your PC (by following the tutorial here: Setting up your PC).

Step 1: Setup ROS 2 workspace

Open a new terminal on your PC, then copy and paste the following one line at a time:

mkdir -p ~/ros2_ws/src
cd ~/ros2_ws/src

Step 2: Clone the repository

In the same terminal (or in a new one), copy and paste the following:

cd ~/ros2_ws/src
git clone https://github.com/PARC-Robotics/PARC2024-Engineers-League.git .

Step 3: Install dependencies

The cloned project repository contains ROS packages that require certain dependencies before they can be used. These dependencies are specified in the respective package.xml file of each package and are installed using rosdep a command-line utility for identifying and installing dependencies to build or install a package.

To install the project dependencies, un the same terminal (or in a new one), copy and paste the following:

cd ~/ros2_ws
sudo rosdep init
rosdep update
rosdep install --from-paths src --ignore-src --rosdistro humble -r -y

Step 4: Set up ROS 2 environment

The following command needs to be run in every new terminal you open to get access to ROS 2 commands:

source /opt/ros/humble/setup.bash

To avoid sourcing the ROS setup file every time you launch a new terminal, you can add the command to your shell startup script by executing these lines:

echo "source /opt/ros/humble/setup.bash" >> ~/.bashrc
source ~/.bashrc

The ros2_ws workspace is an overlay on top of the ROS installation, which is known as the underlay, and similarly to use the package executables or libraries in ros2_ws, the workspace will need to be sourced in every new terminal opened with this command:

source ~/ros2_ws/install/setup.bash

Likewise to avoid manually sourcing the workspace in each newly launched terminal, the command can also be added to shell startup script:

echo "source ~/ros2_ws/install/setup.bash" >> ~/.bashrc
source ~/.bashrc

Note

As you develop, it is good to set the environment variables whenever you run a colcon build command to compile changes to your packages. You can do that by:

source ~/ros2_ws/install/setup.bash

Step 5: Compile packages

The next step is to compile the installed packages using colcon build:

cd ~/ros2_ws
colcon build

Step 6: Gazebo Classic installation and setup

Gazebo Classic, version 11, is the robot simulator used in the competition and can be installed here.

The tomato field is made up of custom models, the tomato plants for instance, that are not available in Gazebo. These models are present in the models folder in the parc_robot_bringup package. To completely view the tomato field in Gazebo, the path to the models folder is made to Gazebo by executing the following commands one after the other:

echo "export GAZEBO_MODEL_PATH=:$HOME/ros2_ws/src/parc_robot_bringup/models" >> ~/.bashrc
source ~/.bashrc

Ensure that the workspace directory is correctly typed out assuming that a different workspace from ros2_ws is used.

Note

The 3D visualizer for ROS, RViz, is automatically installed when ROS 2 Humble was installed on your PC in the setting up your PC tutorial.

Step 7: Test installation

If you completed the preceding tasks successfully, you should be able to run this ROS 2 launch command and see the Gazebo Classic simulator and RViz simulator open with the following display:

ros2 launch parc_robot_bringup task1_launch.py

Gazebo Classic Simulator window

RViz window

If you run the following command in a new terminal,

rqt_graph

You will see a screen like this:

You need to publish/write to the topic robot_base_controller/cmd_vel_unstamped to move the robot. The following guide will help you control the robot using keyboard. Once you have tested that, you can follow the getting-started-with-ros guide to write a python program to control the robot.

Step 8: Controlling the robot using keyboard

First of all, the teleop_twist_keyboard ROS 2 package is installed which will enable us to use the keyboard to control the robot in a terminal as follows,

sudo apt install ros-humble-teleop-twist-keyboard

Then run the following command in a new terminal,

ros2 run teleop_twist_keyboard teleop_twist_keyboard --ros-args --remap \
/cmd_vel:=/robot_base_controller/cmd_vel_unstamped

Now keeping this second terminal active (or on top) press i to move the robot forward, you can see the robot moving in the “RViz” and “Gazebo” windows. You can use the keys shown below to move the robot and k key to stop the movement.

Moving around:
   u    i    o
   j    k    l
   m    ,    .