launch_system_modes

System modes specific extensions to the launch tool, i.e. launch actions, events, and event

handlers for system modes.

README

General information about this repository, including legal information, build instructions and known issues/limitations, can be found in the README of the repository root.

The launch_system_modes package

This ROS 2 package provides a launch actions, events, and event handlers for the use of the system_modes package.

General information about this repository, including legal information, project context, build instructions and known issues/limitations, are given in README.md in the repository root.

Launch System Modes Package

The actions, events, and event handlers implemented for system modes are:

Actions

Two launch actions are implemented for system modes:

  • System: Declares a system, consisting of further system parts, allowing system mode specific launch events and event handlers.

  • Node: Declares a node, i.e. a lifecycle node with system modes. It inherits from the launch_ros/lifecycle_node action and allows further system mode specific events and event handlers.

Events

  • ChangeMode: Trigger a mode change in a System or Node

  • ChangeState: Trigger a state transition in a System, since launch_ros/ChangeState only works for lifecycle nodes, not systems.

  • ModeChanged: Emitted when a System or Node changed its mode.

  • StateTransition: Emitted when a System changed its state, since launch_ros/StateTransition only works for lifecycle nodes, not systems.

Event Handlers

  • OnModeChanged: Event handler for mode changes of a System or Node

  • OnStateTransition: Event handler for state transitions of a System

Examples

Two examples show the use of launch_system_modes:

  1. system_modes_examples/launch/example_system_start_drive_base.launch.py starts an actuation system with two system parts, the nodes drive_base and manipulator. It will then:

    1. trigger a configure transition for the drive_base system part (lines 62 - 65)

    2. a state change handler (lines 86 - 90) notices the successful transition and triggers an activate transition for the drive_base system part (lines 67 - 71)

    3. another state change handler (lines 92 - 96) notices the successful transition to active and triggers a mode change of the drive_base system part to its default mode (lines 73 - 77)

    4. a mode change handler (lines 98 - 102) notices the successful transition to the default mode and triggers a mode change of the drive_base system part to its FAST mode (lines 79 - 83)

  2. system_modes_examples/launch/example_system_started.launch.py starts the same system, but uses according events and event handlers for the system instead. It will:

    1. trigger a configure transition for the actuation system (lines 60 - 63)

    2. a state change handler (lines 78 - 82) notices the successful transition and triggers an activate transition for the actuation system (lines 65 - 69)

    3. a mode change handler (lines 84 - 88) notices the successful transition to the default mode and triggers a mode change of the actuation system to its PERMORMANCE mode (lines 71 - 75)