ROS2

View the current image version

cat /etc/version_log

v1.0.25.01.02

myAGV_ROS2 v1.0.25.03.11 image version has completed the function integration of ROS2. You can download the latest image at jump link and burn the image system to the TF card.

v1.0.25.03.11 image version The following parts do not need to be operated, just use it as a reference to understand ros2 knowledge.

If myAGV_ROS2 is the v1.0.25.01.02 image system, you can adapt the ros2 function according to the following operations.

If it is not this version, you can go here to download the system image of v2025102 and follow this instructions) to operate.

Modify ~/.bashrc to switch the environment variables of ros1 and ros2

Click on er's Home, then press Ctrl + H on the keyboard to open the hidden file and find the .bashrc file.

These four lines of ros1 environment variables.

source /opt/ros/noetic/setup.bash
source ~/myagv_ros/devel/setup.bash
export ROS_HOSTNAME=localhost
export ROS_MASTER_URI=http://localhost:11311

Rewrite as follows, add ros2 environment variables.

echo "ros noetic(1) or ros2 galactic(2)?"
read edition
if [ "$edition" -eq "1" ];then
    source /opt/ros/noetic/setup.bash
    source ~/myagv_ros/devel/setup.bash
    export ROS_HOSTNAME=localhost
    export ROS_MASTER_URI=http://localhost:11311
    echo using ros noetic
else 
    source /opt/ros/galactic/setup.bash
    source ~/myagv_ros2/install/local_setup.bash
    echo using ros2 galactic
fi

Each time you open the terminal, you need to enter the number "1" or "2" to activate the ros1 or ros2 environment.

Compile ros2 code

Open a terminal and pull the galactic-JN branch code of myagv_ros2.

git clone -b galactic-JN https://github.com/elephantrobotics/myagv_ros2.git myagv_ros2/src

Then, install the dependency package through rosdep.

cd ~/myagv_ros2
rosdep install --from-paths src --ignore-src -r -y

You also need to manually install the following dependency packages.

sudo apt install ros-galactic-bondcpp \
    ros-galactic-test-msgs* \
    ros-galactic-behaviortree-cpp-v3* \
    ros-galactic-ompl \
    ros-galactic-joint-state-publisher \
    ros-galactic-rqt-tf-tree \
    ros-galactic-diagnostic-updater \
    ros-galactic-camera-info-manager -y

Finally, compile the source code. The first compilation process will be slow and you need to wait patiently.

Note: Be sure to compile in the ~/myagv_ros2 path

colcon build

If the compilation is successful, the message Summary: xxx packages finished will be displayed.

After each compilation, remember to source the ros2 environment variables.

source install/local_setup.bash

myagv_ros2 is managed on github and can be updated to the latest version via git.

cd ~/myagv_ros2/src

git pull

cd ..

colcon build

ROS2 Basics

• ros1 components use c++/python, ros2 components use c/python;
• ros1 only supports Linux and MacOS, while ros2 supports Linux/Windows/MacOS/RTOS;
• ros1 communication is based on TCPROS/UDPROS, which strongly depends on the processing of the master node, while ros2 is based on DDS (distributed architecture);
• ros2 supports real-time control;
• ros2 widely uses C++11 and Python3.5 and above;
• ros2 uses a new compilation system Ament;
• ros2 communicates with ros1 through ros_bridge;
• ros2 uses managed startup: users can specify the node startup order;
• ros2 cancels the concept of nodelet and supports multi-node initialization;
• ros2 launch files are written in python, which expands functionality compared to xml.

The ros2 command changes are as follows

rosrun --> ros2 run
rosnode --> ros2 node
roslaunch --> ros2 launch
rosparam --> ros2 param
rospkg --> ros2 pkg
rosservice --> ros2 service 
rossrv --> ros2 srv
rostopic --> ros2 topic
rosaction --> ros2 action

clocon build

• --packages-up-to: Build the package you want, and all its dependencies, but not the entire workspace (saves time)
• --symlink-install: Saves you from having to rebuild every time you tweak your Python scripts
• --event-handlers console_direct+: Show console output while building (otherwise available in the log directory)
• --executor sequential: Process packages one by one, instead of using parallelism

Compile only the packages you want

colcon build --packages-select my_package

Limit the number of cores

colcon build --jobs 2

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