ROS2 Node

A ROS2 node that connects to a robot to enable interaction through ROS2 topics and services.

Using the ROS2 node

The ROS2 node is a stand-alone application that connects to a robot using the CreOS Client library, and exposes all the library's interfaces as ROS2 interfaces on your ROS2 network. To use the ROS2 node, you should first install it as described in the Installation section. The node can be launched using the provided launch file, replacing the <robot-address> placeholder with the address of the robot:

ros2 launch creos_sdk_ros creos-ros-wrapper.launch.yaml host:=<robot-address>

You can also change the namespace of the node by setting the ns launch argument. By default, the ROS2 node will use the /robot/ namespace.

You can also run the node directly as follows:

ros2 run creos_sdk_ros creos-sdk-ros --ros-args -p host:=<robot-address>

Talking to the ROS2 node

Once you have the ROS2 node running, you can interact with the robot using the ROS2 topics and services it provides. You can do this using the ROS2 command line tools...

# publish a velocity command to the robot
ros2 topic pub /robot/cmd_vel geometry_msgs/msg/Twist "{linear: {x: 0.1}, angular: {z: 0.1}}"
 
# request robot to enter low power mode
ros2 service call /robot/enter_low_power_mode creos_sdk_msgs/srv/EnterLowPowerMode
 
# subscribe to the battery status
ros2 topic echo /robot/battery

...or by writing your own ROS2 nodes in C++ or Python. To be able to use all topics and services, you should have the creos_sdk_msgs package installed. This package is included with the creos-sdk-ros package.

All the input topics, output topics, and services of the ROS2 node can be found below, including links to the definitions of the message types they use. The Input Topics are topics to which you can publish data. The Output Topics are topics that the node publishes data to. The Services are services that the node provides. They are split into Commands and Getters. Commands allow you to send commands to the robot, while Getters allow you to pull data from the robot. The response types of all services include a success field that indicates whether the service call was successful, and a message field that contains an error message if the service call was not successful.

Input Topics

Only show topics that are supported for:

Topic	Type	Quality of Service setting		Description	Supported platforms
		Reliability	Durability
cmd_vel	geometry_msgs::msg::Twist	Best effort	Volatile	Publish a velocity command to the robot.
cmd_state_ref	creos_sdk_msgs::msg::StateReference	Best effort	Volatile	Publish a state reference to the robot.

Output Topics

Topic	Type	Quality of Service setting		Description	Supported platforms
		Reliability	Durability
lidar/front/points	sensor_msgs::msg::PointCloud2	Best effort	Volatile	Subscribe to the point cloud data from the front-facing LIDAR sensor.
odometry	nav_msgs::msg::Odometry	Best effort	Volatile	Subscribe to the odometry data.
pose	geometry_msgs::msg::PoseWithCovarianceStamped	Best effort	Volatile	Subscribe to the global pose data.
gnss	sensor_msgs::msg::NavSatFix	Best effort	Volatile	Subscribe to the GNSS data.
joy	sensor_msgs::msg::Joy	Best effort	Volatile	Subscribe to the remote controller state data.
joint_states	sensor_msgs::msg::JointState	Best effort	Volatile	Subscribe to the wheel state data.
magnetic_field/body	sensor_msgs::msg::MagneticField	Best effort	Volatile	Subscribe to the magnetic field data in the body frame.
barometer	sensor_msgs::msg::FluidPressure	Best effort	Volatile	Subscribe to the barometer data.
range/downwards_lidar	sensor_msgs::msg::Range	Best effort	Volatile	Subscribe to the range data from the downwards-facing LIDAR sensor.
imu/body	sensor_msgs::msg::Imu	Best effort	Volatile	Subscribe to the IMU data in the body frame.
system_info	creos_sdk_msgs::msg::SystemInfo	Reliable	Transient local	Subscribe to system info messages.
battery	creos_sdk_msgs::msg::BatteryStatus	Reliable	Transient local	Subscribe to battery status updates.
tf_static	tf2_msgs::msg::TFMessage	Reliable	Transient local	Subscribe to transformation frame messages for static transformations.
tf	tf2_msgs::msg::TFMessage	Reliable	Volatile	Subscribe to transformation frame messages for dynamic transformations.
current_control_source	creos_sdk_msgs::msg::ControlSource	Best effort	Volatile	Subscribe to the current control source of the robot.
state	creos_sdk_msgs::msg::State	Reliable	Transient local	Subscribe to state information of the robot.
user_events	creos_sdk_msgs::msg::UserEvent	Reliable	Transient local	Subscribe to user events generated by the robot.

Services

Commands

Service	Type	Description	Supported platforms
enter_low_power_mode	creos_sdk_msgs::srv::EnterLowPowerMode	Enter low power mode.
exit_low_power_mode	std_srvs::srv::Trigger	Exit low power mode.
shutdown	std_srvs::srv::Trigger	Shutdown the robot.
reboot	std_srvs::srv::Trigger	Reboot the robot.
set_control_source	creos_sdk_msgs::srv::SetControlSource	Set the control source of the robot.
send_command	creos_sdk_msgs::srv::SendCommand	Send a command to the robot to trigger a one-time action.

Getters

Service	Type	Description	Supported platforms
get_system_info	creos_sdk_msgs::srv::GetSystemInfo	Get the system info.
get_battery	creos_sdk_msgs::srv::GetBatteryStatus	Get the battery status.
get_control_source	creos_sdk_msgs::srv::GetControlSource	Get the current control source of the robot.
get_state	creos_sdk_msgs::srv::GetState	Get the state of the robot.