Requirements

• Ubuntu 22.04, ROS2 Humble, Gazebo Fortress

• sudo apt install ros-${ROS_DISTRO}-realsense2-camera && ros-${ROS_DISTRO}-realsense2-description && ros-${ROS_DISTRO}-rtabmap-ros && ros-${ROS_DISTRO}-imu-tools && ros-${ROS_DISTRO}-rviz2 && ros-${ROS_DISTRO}-rqt && ros-${ROS_DISTRO}-tf2-tools && ros-${ROS_DISTRO}-ros-gz && ros-dev-tools

• In your ~/.bashrc, add the following

  source /opt/ros/humble/setup.bash

  source /usr/share/colcon_argcomplete/hook/colcon-argcomplete.bash

  source /usr/share/colcon_cd/function/colcon_cd.sh

Step by step instructions to ROS2 Navigation stack

Setup your colcon workspace

• mkdir -p ~/skidy_ws/src
• cd skidy_ws/src
• git clone https://github.com/ashBabu/skidy.git
• git fetch origin --prune
• cd skidy
• git checkout ros2-ignition-gazebo
• cd ~/skidy_ws
• colcon build --symlink-install
• source install/setup.bash

Differences that I found in Gazebo Fortress compared to classic gazebo (gazebo_ros)

• Topics published can only be viewed by the command ign topic -l. The subscribed topics remain hidden
• All topics published or subscribed by Fortress requires a ros_ign_bridge to be available in ROS as in here
• The /clock is published by Fortress but not available in ROS by default even though there is /clock displayed by the command ros2 topic list. For this to be available, the bridge needs to be properly set up. This is a unidirectional message from Fortress to ROS provided by the symbol [. More details here
• For other msg types, set up the brige as required. Documentation available here
• Echo command in Fortress is ign topic -e -t /topic_name
• Although Fortress is the recommended version of ROS2 Humble, the namespace ignition has already been replaced by gz

Launch

• ros2 launch skidy_bringup bringup_sim.launch.py
• Press the play button in Gazebo fortress

To publish to cmd_vel topic

• ign topic -t "/cmd_vel" -m ignition.msgs.Twist -p "linear: {x: 0.5}, angular: {z: 0.5}"

                                OR
  

• ros2 topic pub /cmd_vel geometry_msgs/msg/Twist "{linear: {x: 1.0, y: 0.0, z: 0.0}, angular: {x: 0.0, y: 0.0, z: 1.0}}"

Notes

• The topic cmd_vel or something that you prefer has to be set specifically in the plugin that you use (example). By default, this topic name is something weird like /robot_name/.../cmd_vel and work only if you have properly set up the ros-ign_bridge to transfer msgs from Fortress to ROS

Current issues

• If the differential drive plugin in activated (commenting out the odometry and velocity plugin) in robot_urdf, publishing to cmd_vel steers the robot straight even though there is an angular velocity specified.

diff_drive_plugin.mp4

• The odom to base_link transform is missing with differential drive plugin

• Without a joint_state_publisher (already have robot_state_publisher), the continuous joints are not recognized by the tf-tree. Rviz2 shows a warning

  [rviz2-6] Warning: Invalid frame ID "drivewhl_r_link" passed to canTransform argument source_frame - frame does not exist
  [rviz2-6] at line 93 in ./src/buffer_core.cpp
  

• Enabling the odometry and velocity plugin (commenting out diff drive) in robot_urdf, behaves more or less like what a differential drive plugin should do

odom_velocity_plugin.mp4