Services

To run all ROS 2 nodes in the background and from boot, we use robot_upstart to install the launch files as systemd services. In ROS 1 there was a single ros service that ran everything. For ROS 2 Humble, we have split this into three separate services: Platform, Sensors, and Robot.

Clearpath Platform

The clearpath-platform service launches the platform-service.launch.py file found under /etc/clearpath/platform/launch/. This will launch the nodes required to operate the base platform, such as control, teleop, localization, and more. Running this service alone is enough to drive the robot, visualise it in Rviz, and get platform data. This service can be stopped or started without interrupting the sensor service.

Clearpath Sensors

The clearpath-sensors service launches the sensors-service.launch.py file found under /etc/clearpath/sensors/launch/. This will launch any sensors defined in the robot YAML. This service can be stopped or started without interrupting the platform service.

Clearpath Robot

The clearpath-robot service is the "parent" service of clearpath-platform and clearpath-sensors. If it is restarted, then both the platform and sensors services will restart. This service will run all of the generators in the PreExec step, before allowing the two dependent services to start. While the platform and sensors services are running, the robot service will periodically check for changes in the robot.yaml file. If a change is detected the service restarts, re-generating all files and restarting the platform and sensors services.