Hayden_ROS2_demo

A repo for me to record ROS2 learning process and demonstration projects
email: YetWhen@gmail.com/Diwen.Ye@unswalumni.com

created at 2024/05/17

Environment and system setup

UBUNTU 22.04 Jammy Jellyfish
ROS2 humble
builder: ament, colcon
ros2 package: urdf_tutorial
vscode extensions:
  c/c++ (by microsoft)
  CMake (by twxs)
  Python (by microsoft)
  ROS (for urdf xml coding)
for sim_ws>>URDF files, xacro is used and need to be installed by following command:
  sudo apt install ros-<distro>-xacro

basic setup commands

The following commands shall be run everytime when a new shell or terminal window is opened.
To make the system automatically call these files, you can paste these commands at the end of ~/.bashrc file

to access ros2 commands

source /opt/ros/humble/setup.bash

to access developer tools

assuming colcon is installed with default setting
source /usr/share/colcon_argcomplete/hook/colcon-argcomplete.bash

to access gazebo

after install ros2, may also need to run
sudo apt install ros-humble-gazebo* (include the *)
Then run the following env source command or add to ~/.bashrc

source /usr/share/gazebo/setup.bash

to access the firstROS2_ws workspace

if ROS2_demo diretory is installed in home diretory, otherwise change ~ to the address to ROS2_demo
source <PATH_TO>/ROS2_demo/firstROS2_ws/install/setup.bash
firstROS2_ws can be replaced to the folder name of other workspace

for c++ ros2 library reference (VSCode user)

the #include "<ANY_ROS2_LIBRARY_OR_INTERFACE>" maynot be recognised by IDE gramma check
ctrl+shift+P -> search for "C/C++ Edit Configuration JSON"
edit the c_cpp_properties.json, add to '"includePath:["${workspaceFolder}/**",]"
with address to local ros include folder, eg.
/opt/ros/humble/include/**
Additionally, for any customized interface (already built and installed to workspace, add the address to installed interface package's include folder.
Format would be
[ADDRESS_TO_WS]/install/[INTERFACE_PKG]/include/**
eg.
~/ROS2_demo/firstROS2_ws/install/my_interfaces/include/**
(assuming ROS2_demo is installed to home)

firstROS2_ws

My learning process following tutorial guides.
Contains 4 packages, my_cpp_pkg， my_python_pkg, my_interfaces and my_robot_bringup
All the source files/codes are fully functional and can serve as template for further project
Topics covered:

my_cpp_pkg & my_python_pkg

simple node, topic publisher (with&without oop), topic subscriber (with&without oop), ROS2 service server, ROS2 service client, ROS2 parameters
all of the source files can serve as template for further project

my_interfaces

customized interfaces for msg & srv

my_robot_bringup

calling nodes and configure node parameters via launch file.

Heavily commented.

sim_ws

default functionality (as template):
Launch robot urdf in gazebo and rviz
ros2 launch my_robot_bringup my_robot_gazebo.launch.xml
It will also Enable the gazebo plugin from gazebo_ros pkg, which is a 2 wheel controller for robot, subscribing the topic /cmd_vel
To publish a simple topic for debugging
ros2 topic pub /cmd_vel/geometry_msgs/msg/Twist "{linear: {x: 0.5}, angular: {z: 0}}"
To publish topics in node, refer to the publisher examples in firstROS2_ws

my_robot.urdf

A simple car with 2 wheels and a caster wheel, can serve as template of urdf file
simple way to investigate the urdf file is using urdf_tutorial package
ros2 launch urdf_tutorial display.launch.py model:=address/to/my_robot.urdf
which will call Rviz2 with appropriate configuration
details on joint & link type:
wiki.ros.org/urdf/XML/joint
wiki.ros.org/urdf/XML/link

add gazebo plugins to urdf files

examples in src/my_robot_description/urdf/mobile_base_gazebo.xacro
ros gazebo plugins github (ros-simulation/gazebo_ros_pkgs) ros2 branch
gazebo_plugins/inlcude/gazebo_plugins/ folder contains most of the header files for documentation reference