ROS2 Control

ros2_control Concepts & Simulation

ros2_control Concepts & Simulation

Add ros2_control to Gazebo

• Install dependencies
  • ros-humble-ros2-control: Core control framework for robot hardware interfaces and controllers.
  • ros-humble-ros2-controllers: Predefined controllers that can be used to control robot hardware.
  • gz_ros2_control: Integration between ROS 2 control framework and Gazebo
    • See gz_ros2_control for installation

sudo apt update
sudo apt install ros-humble-ros2-control ros-humble-ros2-controllers ros-humble-gz-ros2-control

• Create ros2_control.xacro

<?xml version="1.0"?>
<robot xmlns:xacro="http://www.ros.org/wiki/xacro" name="robot">
 
    <ros2_control name="GazeboSystem" type="system">
        <hardware>
            <plugin>gazebo_ros2_control/GazeboSystem</plugin>
        </hardware>
        <joint name="left_wheel_joint">
            <command_interface name="velocity">
                <param name="min">-10</param>
                <param name="max">10</param>
            </command_interface>
            <state_interface name="position" />
            <state_interface name="velocity" />
        </joint>
        <joint name="right_wheel_joint">
            <command_interface name="velocity">
                <param name="min">-10</param>
                <param name="max">10</param>
            </command_interface>
            <state_interface name="velocity" />
            <state_interface name="position" />
        </joint>
    </ros2_control>
 
    <gazebo>
        <plugin name="gazebo_ros2_control" filename="libgazebo_ros2_control.so">
            <parameters>$(find differential_drive_robot)/config/my_controllers.yaml</parameters>
        </plugin>
    </gazebo>
 
</robot>

• Create my_controllers.yaml

controller_manager:
  ros_parameters:
    update_rate: 30
    use_sim_time: true
 
    diff_cont:
      type: diff_drive_controller/DiffDriveController
    
    joint_broad:
      type: joint_state_broadcaster/JointStateBroadcaster
 
 
diff_cont:
  ros__parameters:
 
    publish_rate: 30.0 # You can set this higher than the controller manager update rate, but it will be throttled
    base_frame_id: base_link
 
    left_wheel_names: ['left_wheel_joint']
    right_wheel_names: ['right_wheel_joint']
    wheel_separation: 0.35
    wheel_radius: 0.05
 
    use_stamped_vel: false
 
# joint_broad:
#   ros__parameters:
 

• Build package

colcon build --symlink-install

• Run Gazebo

ros2 launch differential_drive_robot launch_sim.launch.py

• Interact with ros2_control

ros2 control list_hardware_interfaces

command interfaces
	left_wheel_joint/velocity [available] [unclaimed]
	right_wheel_joint/velocity [available] [unclaimed]
state interfaces
	left_wheel_joint/position
	left_wheel_joint/velocity
	right_wheel_joint/position
	right_wheel_joint/velocity

• Start the controllers

ros2 run controller_manager spawner diff_cont
ros2 run controller_manager spawner joint_broad

[INFO] [1743934132.244921802] [spawner_diff_cont]: Loaded diff_cont
[INFO] [1743934132.425982699] [spawner_diff_cont]: Configured and activated diff_cont
[INFO] [1743934133.895245790] [spawner_joint_broad]: Loaded joint_broad
[INFO] [1743934134.168910213] [spawner_joint_broad]: Configured and activated joint_broad

• Gazebo feedback that it started

[ruby $(which gz) sim-2] [INFO] [1743934132.144893051] [controller_manager]: Loading controller 'diff_cont'
[ruby $(which gz) sim-2] [INFO] [1743934132.248650924] [controller_manager]: Configuring controller 'diff_cont'
[ruby $(which gz) sim-2] [INFO] [1743934133.736394068] [controller_manager]: Loading controller 'joint_broad'
[ruby $(which gz) sim-2] [INFO] [1743934133.898670853] [controller_manager]: Configuring controller 'joint_broad'
[ruby $(which gz) sim-2] [INFO] [1743934133.898985579] [joint_broad]: 'joints' or 'interfaces' parameter is empty. All available state interfaces will be published

• Enable teleop_twist_keyboard by remapping /cmd_vel topic to /diff_cont/cmd_vel_unstamped

ros2 run teleop_twist_keyboard teleop_twist_keyboard --ros-args -r /cmd_vel:=/diff_cont/cmd_vel_unstamped

• Check if controllers are properly loaded

ros2 control list_controllers

joint_broad joint_state_broadcaster/JointStateBroadcaster  unconfigured

• Install ros-gz-bridge

sudo apt-get install ros-humble-ros-gz-bridge